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Russell.K 06-19-2013 05:28 PM

Loose Rockers
 
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Hi, I have a chevy small block 350 out of a 75 Camaro. Everything is stock on the engine. I believe they are hydraulic lifters in the engine. When i tighten the rockers till the pushrods don't move then go another 1/4-1/2 turn, they seem fine and tight. But after i go through them all, they get loose again. The nuts holding the rockers down don't back out at all and the engine doesnt even have to be running to loosen them. Do I just keep tightening them or what? Thanks

BOBCRMAN@aol.com 06-19-2013 07:24 PM

Common with older stuff. The lifters are just leaking down to zero lash. Do not re-tighten.. they will run fine..

tresi 06-19-2013 08:43 PM

You are making sure the lifter is on the base circle of the cam when you're adjusting them? Just checking.

Russell.K 06-19-2013 09:00 PM

Yes I made sure its on the base circle

MouseFink 06-20-2013 07:42 AM

In order to set the lifter preload, the lifters must be on the base circle of the cam lobes. Find zero preload by up and down movement of the pushrod before adjusting 1/2 to 3/4 turn.

First, get a small artists paint brush and white paint. Mark off the harmonic damper in quarters from 0 timing mark, #1 piston TDC on compression stroke.

#1 TDC...........set int. / exh. on #1
1/4 turn CW....set int. / exh. on #8
1/4 turn CW....set int. / exh. on #4
1/4 turn CW....set int. / exh. on #3

Continue 1/4 turn and set preload in that manner according to the firing order. That will guarantee the lifters will be on base circle (overlap) of cam lobes when they are adjusted.
Firing order: 1 8 4 3 6 5 7 2.

496CHEVY3100 06-20-2013 08:56 PM

OR the cam is going flat.Hope not.

you can adjust with engine running back off rocker until click is heard then tighten rocker I/8 turn at a time untill you get 1/4 to 1/2 turn .only tighten 1/8 at a time will give lifter time to pump ,will make a mess unless you have rocker arm clips.

reevislong 06-20-2013 10:39 PM

lifters could be weak bleeding off or it could have a set of antipumpups in which case god help you! or like the previous comment flat lobes?

cobalt327 06-21-2013 02:00 AM

Quote:

Originally Posted by Russell.K (Post 1686665)
Hi, I have a chevy small block 350 out of a 75 Camaro. Everything is stock on the engine. I believe they are hydraulic lifters in the engine. When i tighten the rockers till the pushrods don't move then go another 1/4-1/2 turn, they seem fine and tight. But after i go through them all, they get loose again. The nuts holding the rockers down don't back out at all and the engine doesnt even have to be running to loosen them. Do I just keep tightening them or what? Thanks

Totally normal. Do not adjust twice.

Adjusting hydraulic lifters.

78C10 sleeper 06-23-2013 07:55 PM

Mine did that. My rocker studs where pulling out just lay a strait edge on them and check I always do

cobalt327 06-24-2013 05:27 AM

Quote:

Originally Posted by 78C10 sleeper (Post 1687880)
Mine did that. My rocker studs where pulling out just lay a strait edge on them and check I always do

The difference here is the engine wasn't run between checking the preload. In Russell.K's case, it's bleeding down the lifters from the valve spring pressure.;)

Cobra720 06-30-2013 06:49 PM

Don't worry about how they feel after preload. They will bleed down. As long as you set them the proper way [ and this is the key!!!!! ] just start it up.

Russell.K 07-02-2013 06:29 PM

Thanks guys for the replies!


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