Calgary Jeep Association
4x4 Related Groups => Tech Talk => Topic started by: Gearhead on November 28, 2008, 10:08:51 PM
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Winter is here , it's time for some upgrades.
The plan / mission
I've never been happy with the valve train clatter in my4.0 / 4.7 build , it's a strong engine , pulls hard but I'm not comfortable reving it much past 3500. A while back I bought a selection of parts out of the Mopar performance catalog , then slid the box onto a shelf and forgot about them for a while. Then I laid eyes on a Hesco aluminum cylinder head last week ( not mine :'( ). To say the least it ,was an inspiration . Sadly , I'm not in a position to buy one right now so I decided to go ahead with my original plan , to port a second # 7120 91 - 95 cylinder head casting , this time using + .060" intake and exhaust valves. The valves are not expensive , maybe a couple dollars more than stock , they are stainless steel , swirl polished , hard chromed stems , a bargain at the price I paid. I'll be using Comp cams beehive springs , selected for this application. The beauty of these springs is , a less aggressive spring can be run while maintaining control of the valve train , due to their design and construction , Nascar engine builders have been using them for years , Harley davidson has been using them since 2005 with success and I used them in my buddies 8 second big block drag car heads .Some machining will be necessary to fit the springs.
One of the other items purchased out of the Mopar catalog is a high volume oil pump which delivers a 25% increase in capacity . I also scored a Mopar double roller timing chain set , what is in my engine now is a Comp Cams high energy chain , not a roller but a quality chain that probably has lots of life left in it , I may or may not use the Mopar chain set , havn't decided yet.
Other than a noisy valve train this has been a great engine , doesn't burn or leak a drop of oil , custom length pushrods and adjustable Mopar roller rockers did nothing to quiet the valve train , as a matter of fact , the valvetrain was noisier when the roller rockers were added . At one point a rocker arm broke , there was 5000 km on it at the time , there is close to 10,000 km on this engine now.
I'll be taking some pics of the head work and machining & porting as the work progresses and posting them.
For now , heres some pics of the build , done in the summer of 2006.
The ported head in use now
(http://img.photobucket.com/albums/v29/JeffH/4.jpg)
Some pics of the engine work and assembly
(http://img.photobucket.com/albums/v29/JeffH/RodsnPistons.jpg)
(http://img.photobucket.com/albums/v29/JeffH/ValveGrind.jpg)
(http://img.photobucket.com/albums/v29/JeffH/BlocknCrank.jpg)
(http://img.photobucket.com/albums/v29/JeffH/RollerRockers.jpg)
(http://img.photobucket.com/albums/v29/JeffH/Done-RHS.jpg)
(http://img.photobucket.com/albums/v29/JeffH/ValvetrainTools-2.jpg)
(http://img.photobucket.com/albums/v29/JeffH/SpringTensionGuage.jpg)
(http://img.photobucket.com/albums/v29/JeffH/Valvegrind-1.jpg)
More updates to follow later
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thanks for sharing gearhead
I put a #7120 hesco ( iron ) head on my 4.2L block in '02 - really woke it up - am a big fan of the I6
looking forward to your updates ...
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Thank's , today I'm roughing out the ports , enlarging the seats to accomodate the + .060" valves. Focusing mainly on the exhaust ports , blending the newly enlarged seats into the bowl area of the port , relatively little work is done to the runner area , other than smoothing and knocking down the lumps , casting flash and irregularities. Extreme care is taken when cutting the seats , valve stem protrusion is critical , and plays into both valve train geometry and installed spring height. The seats are integral on cast iron automotive heads , hardened inserts can be installed , a delicate and precise procedure that I'm not yet equipped to do , so care is of the utmost importance so as not to ruin the existing seat material by removing too much .
#7120 castings are desirable for this kind of work , the exhaust ports are less restrictive than later castings. Still a fair bit of work in terms of hours taken to produce a desirable port and convert to larger valves. I'll be doing a four angle valve seat and have created the necessary seat grinding stones , Sioux only supplies 30 and 45 degree stones other angles must be created using spare or additional stones purchased with this in mind with a stone truing fixture that has a diamond cutting tip and can be set at the desired angle you wish. I'll be grinding the valve seats as follows , top cut is 30 , seat cut is 45 , followed by 60 and 75 degree cuts.
The exhaust valves will remain with a single 45 degree angle , a 30 degree back cut is un necessary.
The intake ports , will get done once I am happy with the six exhaust ports. Intake valves will have the 45 and an additional cut , a 30 degree back cut to promote flow early when the valve begins opening. These ports , again recieve more attention in the bowl area , seat enlargement , blending and addressing core shift and irregularities that are commonly found in production castings. Four angle seats on the intake ports too.
The porting and seat work , I'm expecting will take at least two days , the machining on the spring side of the valve and spring set up will probably take the better part of an additional day. I've ordered another cutting tool to prepare the spring seats for beehive springs , there is an existing boss surrounding the valve guide that must be removed , this cutter is one I do not have , so that may not be here for a while , there's no hurry to get this done , springs are on order too.
Nothing happened on this head till it was hot tanked , cleaned , bead blasted , checked for cracks and being straight , this one has less than .002" of warp. and has not been resurfaced (yet ).
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Some progress today , it's warm enough to work outside 8) .
Such dirty work should be done either outside or in a room that can contain the grit and dust generated , personal protectve gear is a must !
#7120 casting 91 - 95 HO model
(http://img.photobucket.com/albums/v29/JeffH/7120casting.jpg)
Notice the position / orientation of the ports , intake being positioned higher than exhaust
(http://img.photobucket.com/albums/v29/JeffH/BV402.jpg)
This exhaust port has been blended , seat cut larger & runners cleaned up.
(http://img.photobucket.com/albums/v29/JeffH/BV404.jpg)
Another view of the same port.
(http://img.photobucket.com/albums/v29/JeffH/BV403.jpg)
Some of the tools used .
(http://img.photobucket.com/albums/v29/JeffH/Portingtools2.jpg)
Progess is slow but happening , lots of breaks and distractions , low stress without setting a deadline .
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Keep posting those pictures.
What this motor going into?
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Keep posting those pictures.
What this motor going into?
It's an upgrade to the engine that's in my 88 YJ , not that it sucks or anything , I'm just doing what I should have done two years ago. I believe the additional oil volume ( new pump ) , may quiet my valve train noise , the rest of it is icing on the cake.
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Stock exhaust valve next to a +.060" exhaust valve.
(http://img.photobucket.com/albums/v29/JeffH/BV4-05.jpg)
As mentioned previously , 7120 castings do flow better on the exhaust side than later heads , there is still room for improvment. Typically , an aftermerket performance camshaft for 4.0 l engines will have additional lift and duration to compensate for restrictive exhaust ports.
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It's sunday , this is my bible.
(http://img.photobucket.com/albums/v29/JeffH/BV406.jpg)
stock valves parked next to the Mopar pieces
In case anyone doesn't know what a beehive valve spring is. This particular set is a little more spring than what is needed for this project and will be used for something a little more "sporty" , I don't need a spring that can handle up to .750" lift for whats happening here . There's a set of titanium retainers too , again overkill , to be used on a future project. The springs selected for this are for .525" max lift , a premium beehive spring used on small block chevrolet and for a cam with similar specs to what I am using on this 4.0 liter
(http://img.photobucket.com/albums/v29/JeffH/BV407parts-1.jpg)
Some of the tools used to wreak havock.
Old school valve seat stones , made by Sioux , the stone prep/ refacer tool is in the right side of the box.
(http://img.photobucket.com/albums/v29/JeffH/Seatgrindstones.jpg)
Mopar double roller timing set , which has three positions for the crank key , not that I am going to advance or retard timing.
(http://img.photobucket.com/albums/v29/JeffH/BV408Timingset.jpg)
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Looks awesome. You can really notice the size difference in those valves.
For the port work, you are mostly smoothing right? You dont really move out a ton of material do you?
So you are thinking about changing up the cam?
Nice to be albe to work outside when its almost the 1st of december....lol
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Not a lot of material being removed , the runners get sanded smooth , rule of thumb is , do not dig into or grind down /enlarge the floor of the port , short side radius get some work , long side radius and bowl area recieves the majority of attention. Each seat get massaged to take advantage of the O/S valves , keeping in mind , to maintain port velocity , there is a venturi in the throat , just above the head of the valve which speeds up airflow and helps with cylinder fill. Carefull manipulation of the die grinder , a keen eye and hundreds of hours doing this kind of work is in my favour. When the air / fuel makes the bend at the end of the port , it speeds up as it passes through the venturi in the valve seat , a stock head has this feature , just a bit crude and un finished , my variation is smooth and refined and must be carefully duplicated across all of the ports. This weekend , I'll be happy to have completed the six exhaust ports , the intakes are next . I'm also sanding and blending the chambers to eliminate sharp edges that promote detonation ( bad ! ).
Change up the cam ? , maybe , I'll probably finish wearing out the cam that's still in there , it's tempting though .
Working outside to do this keeps the shop cleaner , we are fortunate to have this weather , I would like to be out at Mclean today but I'm motivated to get this job under way.
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Cutting / enlarging a seat
Begins with a 45 degree cut , bringing the od of the cut close to the size of the valve.
(http://img.photobucket.com/albums/v29/JeffH/BV4045CUT.jpg)
The seat - a 45 degree cut then gets blackened with a felt pen.
(http://img.photobucket.com/albums/v29/JeffH/Blackenseat.jpg)
The valve is measured , .040" is subtracted and a 30 degree top cut is made to establish the outer most area of the seat. The reason for the - .040" will be explained later.
(http://img.photobucket.com/albums/v29/JeffH/BV4030CUT.jpg)
Selecting a 60 degree stone , the seat is narrowed to the desired width , this establishes the inner edge of where the seat will be . Edit - grinder cam used for this shot.
(http://img.photobucket.com/albums/v29/JeffH/BV4060CUT.jpg)
This 60 cut is followed up with a 75 degree cut , using the custom stone mentioned earlier , we now have a four angle seat , the area that is still black is the seat , the contact area on the face of the valve when it's on it's seat.
(http://img.photobucket.com/albums/v29/JeffH/Fourangles.jpg)
The blending and attention to achieving / restoring a radius then begins , a variety of tools a teqniques used here.
(http://img.photobucket.com/albums/v29/JeffH/Blending1.jpg)
Calipers are used as a means to achieve uniformity among the other port throats.
(http://img.photobucket.com/albums/v29/JeffH/Blending2.jpg)
A variety of sanding cones are used on a mandrel , course , fine , small , large , tapered , etc.
(http://img.photobucket.com/albums/v29/JeffH/Blending3-1.jpg)
A couple of shots of my work area outside , Nov 30th.
(http://img.photobucket.com/albums/v29/JeffH/Workstation.jpg)
(http://img.photobucket.com/albums/v29/JeffH/Workstation3.jpg)
(http://img.photobucket.com/albums/v29/JeffH/Workstation2.jpg)
A standard valve seat grind is not like this , the seats recieve only enough grinding to clean them up and remove pitting which is caused by carbon being pounded in , the valves , if re-used get a good cleaning and a reface on the valve grinding machine to remove pitting and true them up.
Going to larger valves is brutal and barbaric in comparision , savage removal of seat material would ruin an otherwise useable head casting , in this case It's OK , the larger valves do not seat anywhere close to where the originals did , an entirely new seat is established in virgin material.
The project continues..................
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Any one who has been reading along may have wondered about the comment made regarding the 30 degree angle and subtracting .040" from the diameter of the head of the valve , setting a caliper there to measure the outside of the valve seat. I did say I was going to explain later.
Like I said , this establishes the outer edge of the seat. The next cut , at 60 degree determines the inside edge of the seat which in turn gets you the width you are after. A performance valve job calls for a seat width of .050" to .070". Wide seats are bad , carbon gets trapped and then pounded in and can hold a valve open , causing it to burn & fail. Narrow seats are ok but not too narrow , here's why. Valve temperatures run real high , heat in the stem transfers to the guide and head casting , the head of the valve however runs much hotter and can only transfer heat when it's on it's seat . This is only a brief moment in time , a valve spends much of its time open , a function of the sequence of events in valve timing and engine cycles. This is why the engineers that design this stuff decide how wide a seat should be. It's important , if a valve burns , there is gonna be a reason. Some carbon trapped on the seat is normal , over a period of time it tends to pound the seat and form pits , these are cut away when the head is serviced/ rebuilt. Don't be fooled into thinking that simply by taking some lapping compound and lapping a used valve into a used seat is a valve job , it's not . Generally the lapping of valves is not part of a valve job , it is not necessary , todays valve seat reconditioning equipment is far more precise and costly than the old school method shown in this thread. These machines cut all valve angles in one pass with some fancy tooling , cutters that use carbide inserts , grinding seats is not all that common any more.
When I lap a valve , it's not to achieve a seal , it's to get a visual on where the seat wound up on the face of the valve , the sealing function happens quickly on it's own once the engine is fired , the mating surfaces are happy and will hold a seal even before the engine is started but the seal is improved by the two parts repeatedly contacting each other.
I lapped the # 1 exhaust valve to it's seat , again only to get a visual on where the seat wound up , it was .060" wide and centered , as planned . The actual seat will wind up slightly wider than shown, once the engine is run .The dull band shown is the seat area , the presence of lapping compound while lapping , holds the valve off it's seat a tiny bit resulting in the true width not being shown, it will wind up being .070"wide.
(http://img.photobucket.com/albums/v29/JeffH/Exhaustvalveface.jpg)
The valve stem protrusion number I was shooting for wound up being an acceptable number that I'm happy with , considering I'm creating new valve seats in virgin material. The springs being used call for an installed height that will be easily achieved. Variances in valve stem protrusion or numbers that are way out of the norm will wreak havoc with valve train geometry , rocker arm contact problems and issues with pushrod length , requiring custom pushrods. A hydraulic lifter only likes to be preloaded so much.
Other than some final details , a bit more sanding , the exhaust ports are nearly done.
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I have been in alot of machine shops(used to work as an assembler in one), I have to say that from your pics yours is the cleanest & most organized I have ever seen. I dont think I have ever seen a valve grinder that is that spotless & running oil that clean. Two thumbs up I am impressed.
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I have been in alot of machine shops(used to work as an assembler in one), I have to say that from your pics yours is the cleanest & most organized I have ever seen. I dont think I have ever seen a valve grinder that is that spotless & running oil that clean. Two thumbs up I am impressed.
Thank's , I don't believe any of the Sioux stuff here has been used commercially or in an environment where there are a bunch of bozo's running amok , I was very fortunate to find it in that condition. It sees ocassional use , probably has always been that way.
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great work jeff!
nothing like some engine building to get the blood flowing:)
when the head is done, do you spend some time smoothing the ports on the intake and exhaust manifolds as well?
what is your ultimate goal with the port job? the 4.0L is a low end torque engine, and running the higher lift cam i was wondering if you'll end up with a higher air flow through intake-head-exhaust and end up with a higher rpm power band?
im only going from what ive learned through school and reading books and mags. but most books and mags build engine for hi rpm HP, i dont think ive read about building an engine for low rpm torque.
anyways, great thread, always a good read, keep goin!
eric
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There won't be any time spent on manifolds , the intake is quite difficult , frankly almost impossible to reach into the runners by hand , the only practical method I can think of is a process called extrude hone , where an abrasive medium is forced through . It's a paste and is heavily laden wth abrasive material , pushed through from end to end , I've only read about it and not aware of this service being offered in Canada. The exhaust is a Banks header , which is about as good as it gets.
Torque is a function of many factors , valve timing , displacement , stroke being of greater importance than bore , cylinder fill , air velocity , Header primary tube length , collector size and position and more. My goal with this is to increase air flow while maintaining air velocity , in doing so there will be no losses at low rpm . I'm very interested in getting some more top end to fatten up the entire power band , right now it feels flat above 3500 , the valve train noise concerns me too . I'll be going with an increase in oil flow to help keep the lifters and cam happy by using a Mopar performance high volume oil pump . The Comp cams beehive valve springs on order for this project are more stable than the springs that are in there now , greatly reduced harmonics , less inertia and manufactured out of high quality materials. I'm hesitating to change to a different cam right now , the bottom end torque is great as is and I would like to maintain the efficiency of this engine , most of the other cams have a narrow lobe separation angle , this gets you more overlap ,the result being a less efficient engine . Most cams offered for efi use are ground with a wider lobe separation angle than cams for carbureted engines . Efi specific cams ,with thier shorter overlap are also desireable for use in forced induction applications ( turbo).
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are there roller lifters for the 4.0L??? i have a feeling there arent, but figured id see if they are out there...
i do understand the air flow and air speed. i guess over all helping the engine breath easier is the ultimate goal here. what is limiting top end power after 3500 rpm? is it the air flow or is a cam/timing issue?
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very imformative,im learning alot keep up the posts!
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are there roller lifters for the 4.0L??? i have a feeling there arent, but figured id see if they are out there...
i do understand the air flow and air speed. i guess over all helping the engine breath easier is the ultimate goal here. what is limiting top end power after 3500 rpm? is it the air flow or is a cam/timing issue?
Roller lifters ? , nothing I'm aware of , this would require a camshaft that has yet to be invented , the lifters themselves would need a means of preventing rotation in their bores . Other than Hesco , Mopar , Bank's and a few other companies , those of us seeking Jeep performance products have few choices.
My goal with this round of mods is to widen the powerband and lessen the noise of the valvetrain. I had mentioned earlier that it felt flat above 3500 , this is not entireley true , my expectations were not met with the present configuation , the bottom end power has surpassed what I'd hoped for . the 3500 & up part ? , I thought it might be better and it's certainly no dog at any RPM , I feel that limitations , if any , may be tuning , all of the engine management stuff is stock and un molested. I do have an adjustable fuel pressure regulator which is still in it's package , thinking , some day I'll buy some dyno time and have the air / fuel ratio sampled before just slapping on a regulator that's not needed. Also , the way the stock regulator works is , under vacuum the pressure is reduced , when you mash your foot into it , the fuel pressure increases as the vacuum reaches atmospheric pressure . An adjustable regulator can be set to a higher pressure for cruise / light load / high vacuum conditions but the upper end of what pressure is available at the fuel rail is limited to what the pump can produce.
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it would be nice if there was a plug and play stand alone fuel set-up for this engine.i think Painless has a harness for the 4.0L and can come with a new cam with their own computer tune. but i doubt it is as wild as you are going jeff. maybe a stand alone set-up could be adapted. would take a lot of time and effort though. a wide-band O2 sensor could help to dial it in as well i bet.
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it would be nice if there was a plug and play stand alone fuel set-up for this engine.i think Painless has a harness for the 4.0L and can come with a new cam with their own computer tune. but i doubt it is as wild as you are going jeff. maybe a stand alone set-up could be adapted. would take a lot of time and effort though. a wide-band O2 sensor could help to dial it in as well i bet.
The engines / vehicles I work on day to day have some very nice software available to use on our dyno , an interface that marries itself to the vehicle being tuned and offers a variety of tuning variables that can be manipulated to create a custom map suited to the particular engine configuration that has been built. Tuning parameters include , air fuel ratio for each cylinder , volumetric efficiency , startup fuel , warm up fuel , acceleration enrichment , deceleration enleanment , injector size , spark advance , the displacement can be altered using the software as needed , handy when editing each cell in a fuel table , limits are set and can not be exceeded , fooling the software is enabled by increasing the displacment of the engine in the tuning constants tab or by editing fuel injector flow rates , this allows more fuel to be added when required. Dyno runs are made at various throttle positions ( % ) and rpms while sampling air fuel ratios in real time , this data , when sampled and interpreted can then be used to edit fuel tables and a variety of other items . The engine configurations that can be built are staggering , a wide variety of cams , a plethora of exhaust systems , compression ratios , fancy cylinder heads and matching pistons with whizzy domes , stroker cranks , big bore kits , a wide choice of engine displacements , several different throttle bodies , larger fuel injectors , each build requiring it's own custom tune. The release of this software has enabled possibilities on fuel injected engine builds which in the past had to done on a more conservative and civilized level.
A while back we sold piggy back tuning devices too that I'm not very fond of , the tuning product as described above just make more sense. It would be nice if there was software available to tune our Jeeps , there are liabilities to this , in the wrong hands it's not difficult to have a meltdown and wreck stuff. Oh , our dyno , it's motorcycles only , and the badly needed dyno time I might ever get for my Jeep will be at a location , yet to be determined.
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Last month Scott had started a thread about cams n' lifters , then it died off , I figured this discussion was going to lead to some talk about cams and timing , the needs of a fuel injected engine and why there are cams ground specifically for EFI configurations .
http://forum.calgaryjeep.com/index.php?topic=10554.0
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i heard once the reason why nobody really has a plug and play computer that comunicates with the oem computer is because it is physically too difficult to access the factory computer. its easy to get at but chrysler coated the whole ting with that clear hardened goo. but, i think there are ways around that, just nobody has tried hard enough.
then again i did read about the Unichip available for the 4.0L... but iwonder how far you can go with this Unichip...
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i heard once the reason why nobody really has a plug and play computer that comunicates with the oem computer is because it is physically too difficult to access the factory computer. its easy to get at but chrysler coated the whole ting with that clear hardened goo. but, i think there are ways around that, just nobody has tried hard enough.
then again i did read about the Unichip available for the 4.0L... but iwonder how far you can go with this Unichip...
Unichip is (A) piggyback (B) expensive for what you get...
The PCM , is it not blank when new in it's box ? then needs to be flashed to put the correct programing into it ?
Man , I wish I knew more about this Jeep / Chrysler stuff , at Harley , an ECM arrives blank , we then install and flash it with a stock EPA legal map for that model of vehicle. Stage kits are some times used like mufflers and K&N filters , simple mods like this can be tweaked with a stage kit flash , using our laptop and proprietary diagnostic software , this is a one time chargeable deal and further mods will require race tuner software . There are several levels of reflashes but they are not to be stacked or loaded on top of each other , as in , adding additional speed parts later will involve the purchase of software so the customer should just go ahead and have it done at the begining rather than pay for a reflash , then change their mind , add more go fast stuff and have to pay for a flash followed by race tuner software. Also , fewer stage flashes are available now than previously due to 2008 emissions laws in the USA , further and tighter emissions laws are coming , it's gonna get hard to get any performance flashes at all , in some states there are very large fines for tampering.
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It's snowing , so I've got to work inside but the job continues.
Much of the exhaust port and seat work is done but the final details , this week I'm going after the intake side.
Here's the unmolested intake seat
(http://img.photobucket.com/albums/v29/JeffH/BV40stockintseat.jpg)
The intake valves are + .o6o" larger so , like the exhaust side the seats need to go bigger.
It begins with a 45 degree cut , stopping just before the cut reaches the size of the valve head.
(http://img.photobucket.com/albums/v29/JeffH/BV40int45.jpg)
A 30 degree top cut establishes the outer edge of the seat , a 60 degree establishes the inner edge then a 75 degree cut , four angles .
(http://img.photobucket.com/albums/v29/JeffH/BV40fourangleint.jpg)
This process is repeated across all six intake seats before the blending and throat / bowl work begins.
(http://img.photobucket.com/albums/v29/JeffH/BV40intseatcutting.jpg)
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Once all six intake seats are cut and enlarged a Carbide burr in a die grinder is used to blend the bowl area. Attention once again is spent on uniformity , duplicating / enlarging the venturi / throat to suit the larger valves , removing casting flash and smoothing the flaws created during the casting process. Some filing around the valve guides , a bit of tapering to the guide , very little removal of material from the runners , especially the floor , just file down the casting flash and high spots followed by sanding and smoothing.
Here's the first couple being roughed in , ten to fifteen minutes spent on each bowl with the file burr , sanding begins after this.
(http://img.photobucket.com/albums/v29/JeffH/BV40blendfileintbowls.jpg)
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Once I'm happy with the port work , I'll go back and touch up the seats with a fine set of stones , so far it's been coarse stones being used. Several more hours of sanding and blending to do yet , THEN ...............
The spring pads will need to be re-worked. The valves are tilted to the left 15 degrees , creating a small challenge in set up. I'd like to do the machining on a verticle mill , rather than use a hand drill , for a number of reasons. A mill will produce a much more tidy finish , you have greater control on depth of cut by using the dial on the down feed , it's just a whole lot more stable and controllable using a mill. The set up challenge is , the head must be mounted in such a way as to enable the cutter to face the spring pads on a verticle axis , keeping in mind , the valves are tilted 15 degrees. What I do to fixture the head with the guides and spring pads in verticle alignment with the mill spindle is to machine a pair of pedistals which pilot off of the valve guide and seat. The pilots have shoulders that are inserted into two of the valve seats and guides when the head is on the milltable , the spring pads are now in a position where they are square with the mill spindle and can be accurately machined. A Bridgeport or similar milling machine has a head that can be canted at various angles , mine doesn't , it can be rotated or tilted side to side but that is not usefull for this application , the head must be tilted on the mill table.
Heres the pedistal being made
(http://img.photobucket.com/albums/v29/JeffH/Pedistal1.jpg)
Then I made a short .312" pilot to enter the bore of the valve guide
(http://img.photobucket.com/albums/v29/JeffH/Pedistal2.jpg)
Two pedistals , both identical are used to suport the head for milling , this is one of them. I'll be using two 5/16" long studs made out of round bar and threaded on each end , one end threads into a T slot nut in the mill table , the other end protrudes above the guide and a nut is used to hold down the head securely , two hold down studs are used for this.
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Both pedistals are made , some of you may have been wondering what the hell I was talking about , this should make it all clear..................
(http://img.photobucket.com/albums/v29/JeffH/Headonmill-1.jpg)
(http://img.photobucket.com/albums/v29/JeffH/Headonmill-2.jpg)
Studs and T slot nuts are used to secure the head to the mill table for spring pad machining.
The material to be removed is the area surrounding the valve guides , and to clean up the spring pad itself , shown below.
(http://img.photobucket.com/albums/v29/JeffH/7120casting.jpg)
A bunch more blending to do on the intake ports yet and , my cutting tool for the spring pad machining is on order.
Working inside , sanding n' grinding sucks , ugh , dust n' grit.
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Some recent progress , and a down turn in the existing engine.
First the good news
My parts order has arrived , including the springs , retainers , locators , locks and the spring pad cutting tool. The sanding and blending continues and is nearing completion , looking good too ! I also ordered a pushrod length checker which is an adjustable / variable length pushrod , used for mock up , to determine the optimal length that the pushrod should be , when custom length pushrods are being ordered. The last time I ordered shorter pushrods I subtracted the amount of material machined from the cylinder head and block when those were resurfaced and decked , from the length of the stock pushrod , to determine what length of pushrod to order. This works well and allows the lifter to live happily with out being overly compressed , as can happen when using pushrods that are too long. The length checker tool is a more professional way of doing this , being a sucker for gadgets and a certified tool junkie , I just had to have one to add to the valvetrain tool collection.
Now the bad news
Last week a second rocker arm has failed on the way to our club winter camping trip. This happened just south of Longview , strangely within a mile or so of last years rocker arm breakage , that time on the way home. The first incident was north bound on # 22 , the #5 intake rocker broke in half. This time it was the #3 intake. I turned around returned home and changed out all twelve rocker arms , back to the stamped steel stock rocker version , outside in the yard during a howling blizzard , then headed out to make the camping trip without further incident . The engine ran flawlessly for the remainder of the trip. Now , the mystery is , why am I breaking rockers ? , AND , why are some of the other rocker arms showing evidence of the roller tips being side loaded and chewing into the aluminum rocker arms ? . At this stage I can only speculate .
My theory ......... normally in V8 applications , using roller rockers , guide plates are installed under the studs which fasten the rocker arm to the head , to align the pushrods and keep the rocker arms centered over the valve tips , this tends to keep all the parts aligned and happy , getting along together. The mopar performance rocker arms for 4.0 / 2.5 applications do not call for the use of guide plates , resulting in , what I feel to be a lack of stability. The design of Mopar rockers places them in pairs on a shaft , a pair for each cylinder. The rocker arms are located axially on their shaft with thrust washers and retaining rings. They are held down with a 5/16" cap screw , passing through the shaft and a small spacer / pedistal , two being used for each pair of rocker arms. Also , pushrods in these engines are quite long , would there possibly be some sort of flexing / deflection / harmonic deal going on , contibuting to the instability of the valvetrain ?
Until I figure this out or get an answer , I'll not be using roller rockers. I have seen the use of other brands , such as Crower ( AMC V8 ) and guide plates ( OLDS ) on a 4.0 head , requiring some extensive modifications . Whether this is worth it , was a success or not is a grey area , the guy who masterminded it had issues with pushrod / guide plate material incompatability resulting in severe wear / damage to the pushrods. Also I'm aware of a few guys using other brands of roller rockers , some having been in use for a very short time period , I hope this ( my ) situation is unique to Mopar roller rockers and doesn't affect these brands . I'd suggest to these persons , that they moniter and keep an eye on this , it takes very little time to pull a valve cover for inspection.
PICS OF THE FIRST BREAKAGE , Note ! in this pic , the pushrod looks bent , it's not , the picture simply makes it look that way.
(http://img.photobucket.com/albums/v29/JeffH/BrokenRocker-3.jpg)
(http://img.photobucket.com/albums/v29/JeffH/BrokenRocker-1.jpg)
What's a real issue here is , it's about a G note to install this junk , including the 1/2" spacer required for the valve cover and thermostat housing , two high end ( reusable ) Felpro valve cover gaskets are $140!!!!
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very odd indeed jeff. many very out of this world things can happen to an automobile. even things that top techs and teachers will tell you cannot happen... do happen.
something like this makes me wonder if a hydraulic lifter stuck at full length pushed on the pushrod and past the rockers ability, thus breaking it in the exact same spot as the last one. something is causing that push rod to push too high and break the rocker. or, weird as it sounds, the valve is sticking to its seat? i know. very weird. again, weird things happen. but all you can do is narrow down the possibilities.
a bad batch of rockers came from the manufacturer?
aluminium is typically a very stiff material. used where a part is needed to be stiff and have no flex. so im also wondering if a harsh blow caused it to break. and like you said, there is some side loading you cannot explain. maybe a harsh blow as it has some heavy side loads???
but, 2 rockers in 2 years... maybe was just a bad batch of them;)
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Strange that they would walk and wear around the roller like that.
Might have to clamp them down in a vice and do an endplay check on those trunions.
Im going to have mine out by the new year when I do my head. I'll check mine and get you some numbers bud.
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Bill , the rollers can be checked for side play with a feeler guage . I was ina hurry to leave town last week and never had time to be any more scientific than to yank out the old rockers and replace them , um , very quickly.
Some of the Mopar rockers had small nicks in them right out of the box , there's a possibility that failure could have been initiated by a microscopic stress riser.
I doubt there was any other fault in this valvetrain , it ran great before the roller rockers , I installed them and it ran good for 5000 km , then one broke , I removed them and ran with stamped rockers. Later I bought a replacement pair and put the set of R R 's back in , several thousand km later a second rocker broke , they've been removed again and steel rocker arms are back in it. I should add , when they break , there is no warning , just a sudden loss of power accompanied by some klacking. No stuck or bent valves , broken springs , mashed valve seals or bent pushrods , fragments ? none , just a rocker busted in half and a bit of damage to the rocker where the roller is moving laterally. This engine never see's high RPM , I do not beat on it , it's VERY torquey down low so I don't often get my foot into it very far.
Once I get the new cylinder head to a state where the valves and springs are assembled , I'll mock up some roller rockers as well as a pair of stock rockers , on the bench and get a real good look at a few things , till then this is all a mystery
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Some of the Mopar rockers had small nicks in them right out of the box , there's a possibility that failure could have been initiated by a microscopic stress riser.
Let me have a look at them and I should be able to tell you how and where the failure started
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Let me have a look at them and I should be able to tell you how and where the failure started
You are welcome to look at them . It would be best when viewed while I can do a bench top mock up. The valve stem protrusion on this big valve conversion will be very close to a stock 4.0 head enabling an inspection of where the rocker pad or roller would contact the tip of the valve. I can use some light springs that are normally used for valve train set up to do a simulation of valve travel and how the rockers and valves interact together. There's still a bit of machining to do yet .
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Since .......
(http://img.photobucket.com/albums/v29/JeffH/ThisThreadisUseless.jpg)
Here's a couple of pics of those rockers
(http://img.photobucket.com/albums/v29/JeffH/Brokenrockers-2.jpg)
(http://img.photobucket.com/albums/v29/JeffH/Brokenrockers-3.jpg)
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Some more machining done.
Did all of the spring pads today , easy once all of the fixturing was made and the correct cutter in my hands.
(http://img.photobucket.com/albums/v29/JeffH/Springpad-1.jpg)
(http://img.photobucket.com/albums/v29/JeffH/Springpad-2.jpg)
(http://img.photobucket.com/albums/v29/JeffH/Springpad-3.jpg)
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More sanding n' polishing
A couple of views
(http://img.photobucket.com/albums/v29/JeffH/Almostdone.jpg)
(http://img.photobucket.com/albums/v29/JeffH/Almostdone-2.jpg)
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Recent developments and observations.
I'm begining a 2.5 engine build , starting with a spare cylinder head I had laying around.
I took the head apart for cleaning and inspection and noticed a few things............
The lifters can be removed without taking the cylinder head apart , the bores where the pushrods travel are not bores at all like on a 4.0 , they are openings that appear to be large enough to pass a lifter through.
The exhaust ports are somewhat restrictive on the casting I'm using , I'm not sure if this is common to all 2.5's or not , definately room for improvement , very encouraging , there are gains to be made.
The intake ports , although similar to a 4.0 head are positioned lower and do not have a trough that helps direct the fuel discharged from the injector , like a 4.0 head , still some room for improvment here too.
The combustion chambers appear to be smaller than a 4.0 , not a big deal , I like compression any ways , what may be a problem is shrouded intake valves.
Why am I doing a 2.5 ? ? , I need to do one anyway , so why not P & P the head and use a performance cam , a header and decent exhaust.
What has been done with this one so far has helped alot , a 4.0 throttle body , a Flowmaster exhaust , an electric fan , a cold air intake and 4.88 gears.The next phase is to freshen up the engine with whatever is necessary or required and prepare a cylinder head and cam upgrade , probably a Banks header & monster exhaust.
I'll be doing some research as I go , choosing a good cam and stuff .
There's no hurry with this , shooting for completion and install by spring.
Comments ? criticism? suggestions welcome .
I'm looking for cheap , or free cores , donations to my research , 4.2 4.0 2.5 , I could use a 4.0 ( 91 & up ) core that needs rebuilding , or a 4.2 crank n' rods.
The 2.5 core I've got here needs to come apart before I can determine if it's worth rebuilding , plus It's been laying outside for several years ( rusty )
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Update......
I'm 2/3's of the way done with the port work on the 2.5 cylinder head. The exhaust ports cleaned up nicely , the intakes were pretty good to begin with and are looking good too. I am fortunate to have this cylinder head , it's in great shape. The end result will be a vast improvment to the stock 2.5 that's in the 94 YJ now. It was rebuilt in 2005 but recent compression and leakdown testing showed variances in compression and leakage that led to the decision to prepare a replacement engine.
Lady driven means , the hood is rarely lifted to check the oil, it has been found to be run low on oil several times , shortening it's life.
When looking for a used vehicle , ....... BEWARE of the "Lady driven" comment added to many for sale descriptions.
(http://img.photobucket.com/albums/v29/JeffH/Ported25-1.jpg)
The port work will be done today , the valve job is next , I'll be using standard size valves , back cutting the intake valves and cutting four angle seats. I've got to clean up the valves , then decide if I'll buy a set of high flow , stainless valves or not. A performance spring set is being used as will a Hesco cam & lifters.
I have a couple of options............
Plan A
Build a fresh long block with new pistons , bearings , oil pump & timing chain and drop it in shortly after it's ready.
Plan B
Freshen up the engine that was rebuilt in 2005 with whatever is required.
Either way , I should order one of those ridiculous windshield banner stickers , have it printed to say CHECK OIL , then apply it to the inside of the windshield.
Here's what the engine is going in.
(http://img.photobucket.com/albums/v29/JeffH/Oct05LHS.jpg)
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A couple more 2.5 porting pics
(http://
img.photobucket.com/albums/v29/JeffH/Ported25-2.jpg)
(http://img.photobucket.com/albums/v29/JeffH/Ported25-3.jpg)
(http://img.photobucket.com/albums/v29/JeffH/Ported25-Int.jpg)
(http://img.photobucket.com/albums/v29/JeffH/Ported25-Exh.jpg)
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Finished up the four angle valve seats on the 2.5 head today and dug the spare 2.5 core out from under the snow and drug it inside. , it still rotates ! after sitting outside for three years !
(http://img.photobucket.com/albums/v29/JeffH/Ported25-Valveseatsdone.jpg)
(http://img.photobucket.com/albums/v29/JeffH/25core.jpg)
I'm disassembling the short block I have to get an idea on what it's going to need to freshen it up. So far , I've discovered the bores are standard , the rod bearings are standard , the main bearings are standard. I've yet to take some real measurements , a visual inspection looks like rod bearing journals need to be ground - .010" , the mains look good.
There's a raised pad on the upper right side rear area of the block , here there will be a stamped code , this one shows......... 810HX24
What's it mean ?
1st # is the year , this one's an 88
2nd & 3rd is the month , 10 being October
4th & 5th is a letter code HX , that breaks down into 150 cubic inch , 2.5 l , TBI , 9.2:1 compression ratio
6th & 7th #'s = the day of the month , the 24th of October 1988 was when this engine was born.
The disassembly continues and it's time to start a list of parts needed.
The head turned out so nice I'm going to order a set of stainless high flow valves , to go with the fancy cam I've chosen.
A call to Hesco , to order a cam , lifters and springs is on the list of things to do .
I'll be dropping off the block , crank , rods to be hot tanked , checked for cracks , resize the rod big end bores ,bore and hone the block for + .030" pistons , install cam bearings , press the new pistons to the rods , align hone the main bearing bores if needed and more .
I'll have them order me an oil pump , bearings , rings , gaskets n' stuff too.
EDIT........................ !!!!!
Anyone have a pilot bushing for a 2.5 laying around ? I need to know the OD of it , I'm thinkin this engine was in front of an automatic ? , the bore in the back end of the crank is 1.498" , this seems large , like ........ large enough to have the nose of a torque converter stuffed into it ! OR am I panicing unnecessarily and the pilot bushing is in the flywheel , I forget ??? :-[ :-[
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Whoaaa !!!!!!
The brakes have just been slammed on the 2.5 build.
I have pretty much stripped the entire block , in preparation for the hot tank BUT !!
THERE'S A TEN INCH CRACK DOWN THE LEFT SIDE OF THE BLOCK , just below the frost plugs , the external wall of the block is actually heaved outward 1/8" !!!!!!!!! >:( :'( >:( I removed the frost plugs , sprayed some liquid wrench into the cooling jacket and waited , bummer ! it seeped out :'(
The crack !!
(http://img.photobucket.com/albums/v29/JeffH/25Crackedblock.jpg)
:o >:( :o >:( :'( :o :'(
I'm angry now , off to pout , there's gotta be a bottle of dark rum around here somewhere . :P
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where do you get performance cams for the 2.5...
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where do you get performance cams for the 2.5...
From HESCO , no one company has the selection of Jeep / AMC engine parts available that these guys have.
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Some updates
The 2.5 build is on hold for now , the plan is to refurbish the engine that is running and currently being used as a DD. That will happen in the spring , unless I find another 2.5 core to build . I've ordered a bunch of parts to do a 2.5 rebuild , The head work is mostly done , I've ordered hi flow valves for it.
Any one have a 2.5 core laying around ? a carcass , you may be tripping over and want it gone ? , cheap ? free ?
The big valve 4.0 cylinder head is progressing , today , I'm doing the final preparations to the valve seats with a fine set of stones , cut to four angles.
This is a precision valve job , precision means , the seat is exactly where I want it , the face of the valves below show a dull area where the actual seat is and is positioned where I want it , to the outer edge of the valve is a shiny margin area , the dull seat area and above that , a 30 degree backcut. To achieve the dull finish , I use lapping compound , this is merely to confirm & get a visual on where the seat is and how wide , normally valves don't get lapped in , it's not neccessary.
(http://img.photobucket.com/albums/v29/JeffH/FinishedIntakeValves.jpg)
To back cut the valves , the valve grinding machine is set up by angling the chuck portion to grind a 30 degree angle. That cut is above the 45 degree valve face cut . Again , this 30 degree cut is to promote flow early in the intake cycle , when the valve first leaves it's seat in the head and begins opening.
Carfull measuring and grinding puts all of the angles where they are intended to be.
(http://img.photobucket.com/albums/v29/JeffH/BackcutIntakes.jpg)
The exhaust valve are not being back cut , it's not necessary but an equal amont of care is taken to get the same precision and seat placement.
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in either one of your engine builds, when you replace the camshaft with a performance cam, do you plan on changing the camshaft bearings/bushings? something i and another were talking about today?
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in either one of your engine builds, when you replace the camshaft with a performance cam, do you plan on changing the camshaft bearings/bushings? something i and another were talking about today?
Yes , it's part of a proper rebuild. There are exceptions to that.
Let's say you are just changing out the cam & lifters , you shouldn't have to change the cam bearings , that is , if they are inspected and found to be in good condition .
My 94 (2.5 ) had new cam & cam bearings in 2005 , well , ........ new everything in 2005 BUT it has un planned for / unexpected issues, this year I'll be freshening it up . It has developed some odd compression / leakdown #'s and is throwing oil out the dipstick . In dealing with that , I'll be changing out the rings and lower end bearings , deglazing the cylinders , replacing the oil pump , adding a sportier cam and new lifters , installing a double roller timing chain , performance valve springs & the freshly ported head. I'm expecting the cam bearings to be in good condition still , we'll see once the pan is off and the cam is pulled.
Any time a block goes into the hot tank , they must be changed , as well as the frost plugs.
OR
If the person that yanks out the old cam is ham fisted and dings up the bearings while doing so , yes they are going to need replacing.
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I 'm back from training at Nait , and working on the 4.0 stuff.
The head has been resurfaced and painted. I needed to machine the spring pads to increase the valve spring installed height. The springs were dangerously close to coil bind , discovered during mock up and measuring . Not a big deal to correct , .050" of material removed gets things in the safe zone.
(http://img.photobucket.com/albums/v29/JeffH/Machining-3.jpg)
(http://img.photobucket.com/albums/v29/JeffH/Machining-1.jpg)
(http://img.photobucket.com/albums/v29/JeffH/Machining-2.jpg)
Following the machining of the spring seats , is a second mock up to check the installed spring height ......................
(http://img.photobucket.com/albums/v29/JeffH/Installedspringheight.jpg)
Final assembly will be soon after I'm happy with all of the measurments.
The 2.5 ? , I'm gathering parts , rings bearings , gaskets are here now . I have a set of Mopar high flow stainless steel intake valves , the exhaust valves are obsolete :'( . The cylinder head has been resurfaced , the porting and valve seats are done.
I shure would like to find a 2.5 core to rebuild , the one I have is a boat anchor. ( t'was a waste of $$ )
More later
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Time to bring this topic back from being buried several pages down .
What has happened since my last update ?
Um , ........... not much , cash flow has been a problem.
I am going for a final assembly on the fancy big valve 4.0 head , all of the spring set up specs are within allowable tolerances for the cam I'm using.
I would be posting pics of the spring checks / set up / assembly , however , it seems my camera has been laying around since my last wheeling trip and the batteries need to be recharged. The camera is charging , I'll attempt to get some pics and put them up shortly.
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Final assembly pics .................... I managed to get a partial battery charge and click a few pics.
Once I had an installed height for the beehive springs being used , I decided to check the spring tension at that height . This is the closed height , as in when the valve is closed , the springs are holding it on it's seat with X amount of force , X , in this case , being 130 lbs. I also checked the open spring pressure , in this case it is 310 lbs.
(http://img.photobucket.com/albums/v29/JeffH/Finalassy-1.jpg)
Additional checks include valve stem protrusion , used to compare the height of the other valves .
(http://img.photobucket.com/albums/v29/JeffH/Finalassy-2.jpg)
It's also important to know how much travel is available before the retainer / locks mash a valve seal and ruin it . In this case there's room to spare , with the cam I'm using.
(http://img.photobucket.com/albums/v29/JeffH/Finalassy-3.jpg)
Installed spring height is measured , then some math done to determine , where we are in terms of coil bind. Whats coil bind ? , it's when the spring compresses fully and becomes solid , this is real bad ! if it happens , especially if there is additional valve lift yet to happen ! . There needs to be .100" or more of travel available / left over , after subtracting the valve lift # from the installed height# , if not EL BUSTO ! . Mess this up and the springs won't last long , mess it up bad and the valvetrain will self destruct.
(http://img.photobucket.com/albums/v29/JeffH/Finalassy-4.jpg)
One other check that needs doing is to CC the combustion chambers , this gives the engine build guy a number to be used in the calculation of compression ratio.
I'll do that later and post up some pics of the procedure.