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Author Topic:   Hydraulic Lifter chatter
Dirt Roller

Total posts: 14
posted December 12, 2005 10:24 AM  
A buddy of mine is running an old chevy motor with the hydraulic lifters.

The motor started getting a chatter from the valvetrain. He adjusted the lash by the typical method... tighten down until the pushrod gets tight, then go 1/4 turn more. This is with the valve up (closed).

Any suggestions? He had pulled the rocker arms to change the valve seals and when it went back together it started making the noise. Everything went back in its original place.

Are we missing something?


Dirt Maniac

Total posts: 200
posted December 12, 2005 11:10 AM  
Sounds like the cam might be geting a few flat lobes.

Dirt Full Roller

Total posts: 61
posted December 12, 2005 03:00 PM  
Adjusting valve lash can lead to lots of problems if it is not done properly. I've found that the best method is to do each cylinder seperately. Starting with the number one cylinder, crank the motor until the pushrod on the exhaust valve just starts to rise, then adjust the lash on the INTAKE valve of the same cylinder. Once the intake lash is set, crank the engine again until the pushrod on the intake valve has opened the valve and has gone almost completely back down, then adjust the EXHAUST valve of the same cylinder. Do this procedure for each of the eight cylinders. Check the push rods while you are doing the adjustment to make sure they haven't gotten bent (they tend to bend easily if the lash has been adjusted too tight). If they're straight, they should spin freely once any preload is released from them. On hydraulic lifters, tighten the adjuster nut to "just" remove all lash (can't spin push rod with fingers), then preload with about 1/2 turn more.

Good luck, it's very possible that an adjustment error is all that's wrong with the engine.

Normal Sullivan
Dirt Forum Racer

Total posts: 84
posted December 12, 2005 11:30 PM  
Sounds like an error in the adjustment to me. I'd redo it using john56h's procedure if you can't set them with the engine running, which is the best way.

Dirt Maniac

Total posts: 168
posted December 15, 2005 05:46 PM  
set them with engine runing take note of rocker arm motion and push rod rotation (looking for flat cam bent pushrods ect...)

Dirt Full Roller

Total posts: 60
posted December 16, 2005 09:00 PM  
pull it apart and check everything if it is right it is just good fun but if you find the weak link it is money saved

A. Bighurry
Dirt Full Roller

Total posts: 52
posted December 20, 2005 05:44 AM  
If it started right after adjusting the rocker arms it stands to reason that it's the adjustment, not damaged parts. What a lot of people do to set those is to do one cylinder at a time as mentioned before, but completely open one valve, adjust the other rocker. Go to "zero lash" and give it another 1/2 a turn. Now fully open the one you just adjusted, adjust the other rocker arm on the same cylinder. I've done this probably a hundered times and never had a problem.

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