Question about valve lash

S

skav

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Oct 16, 2008
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I just adjusted my valves this weekend, and wanted to ask about factory tolerances.

I didn't check the intake before, but set them to .010 per the manual. I read that they are good from .006-.015.

I did check the exhaust, and they were .026-.027. I set them to .020 per the manual. I believe that spec is .015-.030.

The truck is running a bit quieter. I'm wondering if it would be ok to set them tighter than .010 and .020.

Could I set the intake to .008, and exhaust to .018? Would that quiet the truck a bit more, and add a bit more performance at the same time?
 
I run mine at .008 and .016.

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Stock cam and helix 2. It seemed to help a bit with the stocker but I never checked to see how far out they were to start with.

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chevota84 said:
Stock cam and helix 2. It seemed to help a bit with the stocker but I never checked to see how far out they were to start with.

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Click to expand...


Cool, I'll adjust it tomorrow and give it a try.

Thanks!
 
Don't go tighter that .008 on the intakes because of expansion. The exhaust is good at .015. Each motor is different as far as how it helps.
 
I run .008 and .018, stock cam. Main thing is be as precise as you can setting the valves with each other, it definitely contributes to a smoother running engine. It's amazing how wide of tolerance Cummins allows, if they were adjusted helter skelter but within tolerance it would be a coarse running engine for sure.
 
8&16 for me. I coulda drove a school bus through before I did them... What a difference.

Ed
 
I run a colt stage 3 cam. I was curious on this as well so I adjusted from the normal .010 and .020 to .008 and .016 and saw no gains in quietness, spool up, or performance.
 
According to my factory service manual it doesn't matter as long as it's within the limits. It says no matter what you do it doesn't effect performance, drivability, sound, engine performance, or anything
 
specs are 0.010 intake, 0.020 exhaust on a warm motor.

0.008 intake, 0.018 exhaust on a cold motor (as in sat overnight cold)


I did mine at .010 and .020 after I did my spring and push rod install.
 
.008/.016 is where mine are set on the '03.....no issues at all.

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I have an 02 I recently bought that is supposed to have a Hamilton cam in it. The guy I bought it from didn't know the specs on it and I have not been able to get any answer from the previous owner to him on any of the mods either. Going to check the valve lash on it but had a guy mention doing a "race lash" on it. Bear with me but what is the race lash and is it the best way to go?
 
Probably zero lash with the engine cold. Not ideal for DD-ing.
 
I'd never run with zero lash, but when I worked on old Detriots it was common practice for the older crowd to run them that way. They said it was free power.
 
whitneyj said:
I'd never run with zero lash, but when I worked on old Detriots it was common practice for the older crowd to run them that way. They said it was free power.
Click to expand...

You run 0 on these motors it won't run once warm. Might idle but That's it

phone
 
I run mine at .010 and .010 haven't had a problem yet.

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