opinion on valve stem wear pattern
opinion on valve stem wear pattern OK, got a 408, 04+ 6.0 block bored .30 over, callies stroker crank and rods, roughly 11.1 CR with stock L92 heads, custom synergy can with 236 dur@.050 and .617/.608 lift on a 114 lsa. Using 7.400 push rods and 1.7 non adjustable yella terra rockers the engine runs pretty well for just having a rough tune based on engine specs, but its had an annoying ticking noise since we got it running. The engine sat for awhile after assembly until first fired and I thought maybe it was a lifter or in the tuning. But after almost 200 miles on it so far its definitely valve train noise. Pulled the valve covers today and some of the rockers are alittle loose and I pulled the rockers to see the wear on the stems. Its biased towards the intake on all valves and the wear line seems fairly wide to me. I'm my previous small block and an Olds 455 build the line was more centered and much narrower.
I've ordered a length checking push rod so I can measure but just wanted to get some opinions in the meantime. I'm thinking a longer push rod is needed.
I've ordered a length checking push rod so I can measure but just wanted to get some opinions in the meantime. I'm thinking a longer push rod is needed.
Last edited by HotRodV6; Apr 2, 2012 at 08:38 PM.
I was wondering about that also, as i dont have any shims under them now. But wouldnt you only shim them if you had a slightly to long pushrod? For some reason the pic i uploaded isnt showing up, or atleast for me it isnt.
No...
Shim for wipe pattern and correct the valve train geometry
PR length for lifter preload.
Just keep in mind if you shim your rockers you need to double check your preload to make sure you don't need a longer PR.
Shim for wipe pattern and correct the valve train geometry
PR length for lifter preload.
Just keep in mind if you shim your rockers you need to double check your preload to make sure you don't need a longer PR.
OK, guess there is more to know about these LS valvetrains than the old school SBC. Where can you get shims for these rocker arms?
One other question, i ordered the 7702 length checking pushrod from comp, do you have to swap out the valve springs for some checking springs to use this checking pushrods or can i use it with the patriot gold extreme springs that are in the heads now?
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You use the checker springs from comp.
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There's no need to swap in the lighter checking springs. Those are for checking PTV clearance. You can leave the patriots in while determining the correct pushrod length.
Forget what you learned in setting up the valves on the old SBC. The LS valve set up is kind of backwards from what you did on the SBC.
The shims are nothing special. Just flat steel washers. I bought a bunch of different brands of washers from Lowe's and used a micrometer to measure the thickness of each one and marked it with a felt tip pen. Then sorted by different thickness.
Step 1. Shim pedestal for wipe pattern. You don't have to use the .042" washers from YT. Mine ended up with ~.070" shims. Use a felt tip pen on the valve tip, bolt on the rockers, cycle the valves a couple rounds, remove rockers to see where the pattern ends up. Add/subtract shims until you get a narrow pattern in the middle of the valve tip.
Step 2. Use an adjustable pushrod to determine the right lifter preload from 1/4 turn to 1 turn after zero lash. Order correct length pushrods. Don't pay any attention to what length other guys are using. Measure and then order new purshrods from Comp Cam.
Last edited by Mez; Apr 5, 2012 at 06:36 AM.
