2.5 / 4.0 l Performance

[hps4evr]

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?

[Gearhead]

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.

[Gearhead]

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.

 





Following the   machining  of the spring seats , is a second mock up to check the installed spring height ......................


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

[Gearhead]

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.

[Gearhead]

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.

 



Additional checks include valve stem protrusion , used to compare the height of the other valves .





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.





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.





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.