2.5 / 4.0 l Performance

[Gearhead]

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




Some pics of the engine work and assembly


















More updates to follow later






 

[yjcanibul]

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 ...

[Gearhead]

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 ).

[Gearhead]

Some progress today , it's warm enough to work outside  .

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


Notice the position / orientation of the ports , intake being positioned higher than exhaust


This exhaust port has been blended , seat cut larger & runners cleaned up.


Another view of the  same port.


Some of the tools used .



Progess is slow but happening , lots of breaks and distractions , low stress without setting a deadline .

[rws]

Keep posting those pictures.

What this motor going into?

[Gearhead]

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.

[Gearhead]

Stock exhaust valve next to a +.060" exhaust valve.




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.

[Gearhead]

It's sunday , this is my bible.

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


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.


Mopar double roller timing set , which has three positions for the crank key , not that I am going to advance or retard timing.

[Bnine]

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 

[Gearhead]

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.

[Gearhead]

Cutting / enlarging a seat

Begins with a 45 degree cut , bringing the od of the cut close to the size of the valve.


The seat -  a 45 degree cut then gets blackened with a felt pen.


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.


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.


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.


The blending and attention to  achieving / restoring a radius then begins , a variety of tools a teqniques used here.


Calipers are used as a means to achieve uniformity among the other port throats.


A variety of sanding cones are used on a mandrel , course , fine , small , large , tapered , etc.


A couple of shots of my work area outside , Nov 30th.






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..................

[Gearhead]

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.
 

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.

[4PLAYZJ]

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.

[Gearhead]

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.

[hps4evr]

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