Valve adjust on a small block Chevy
 

with hydraulic lifters, any tips?

This seems like the craziest thing! At least to a Porsche guy.

The accepted method seems to be:

1. Remove valve cover (which, incidentally, is about 3 feet long and held on only by 4 bolts!).

2. With valve cover removed, START THE ENGINE!

3. While the engine is running, loosen the valve rocker nut until the valve starts to clatter. Then tighten it down until it stops clattering, and do a 1/2 a turn more.

4. Repeat for all valves.

Seems a little wacky, and messy to me.

Anyone ever done this? Any tips?

Yeah it was very messy. The last time I did that was in 1980.....long time ago. But that does sound familiar. In fact I'm sure that is what I did. I had bought these clips that clipped over the rockers, if I remember right, kept the oil from going all over. Sorry my memory is not that good anymore.

Thats the way to do it. You can go the feeler guage route too( the best way) but most chevy guys I know do it that way. I use an old valve cover with the top cut off to keep the oil from running all over. the clips are to block the oil that shoots out of the pushrods.

Re: Valve adjust on a small block Chevy
 

Can you not adjust the valves with preload? 1/4 or 1/2 turn past zero lash?


Can you give us any pics of your SBC 924 conversion? :p

Yeah I preload them initialy but always end up going over them with a feeler guage to get the proper lash.

Huh, lash with hydraulic lifters?

http://www.chevelles.com/techref/tecref17.html

http://www.v8s10.org/forum/viewtopic.php?t=81

I used to put a 7 or 8 inch-wide piece of cardboard in the outer edge of the head to capture most of the oil back into the engine, and off of the headers. By the time you are done, there will be no mosquitoes anywhere in the 'hood. But is exactly as described to adjust.

A hydraulic lifter can still be set too tight. or too loose

routine among street racers was non book 1/4 turn past zero years ago.

Zero Lash, means u cant insert a feeler guage. Always have to recheck after engine heats up.

If your are going the clatter route, if you have an old set of valve covers, cut the tops out so you can still get a socket on the rocker, but the sides keep oil from spilling all over the place - much neater.

Gotta think Global... haha The engine would be 'running', unless you were doing them one at a time, leaving the full cover on the other side.

done it many times, I just use cardboard around the engine.

I'd re-check with the feeler as well

Make sure camshaft is at heel (intake / exhaust fully closed) loosen then tighten till you feel very slight drag on pushrod - rotating the pushrod with your fingers - then 1/2 turn.

It doesn't take much - don't be tempted to turn more "just to be sure" - remember once it heats up there's even more lash taken out.

If you set the lash at 1/2 turn it's possible to get 7,000 RPM operation with the right springs - chances are, this won't be necessary but this will get you running.

Get the engine fully heated and listen for clattering (too loose) or sputtering (too tight) and adjust valves accordingy. Place a soaking wet towel on the headers if you need to fix it while running - you can also cut a window into a valve cover if you have a torch..

Hopefully you have roller rockers you're trying this with..

good luck.

rjp

That's pretty much how I remember it. IIRC it was 1/4 turn though.

God, I don't miss SBCs one bit.

Re: Re: Re: Valve adjust on a small block Chevy
 

WTH! You definitely have some secret project going down.

1) how do I take apart a u-joint post
2) how do I adjust the valves on a SBC with hydraulic lifters post
3) how much HP and torque can you put through a 915 post

Using my supercomputer brain, I deduce you are building a super terrific 924 with SBC powerplant turning a driveshaft that extends to your rear mounted, flipped pinion 915 tranny. Let's end this charade--shall we. :D

1/4 turn past zero lash.

Reason why. At high rpm, as oil pressure builds in the system, the pressure exerts force on the piston inside the lifter and lifts it faster than the designed leak down rate can drain the oil.

If there's too much preload, the piston rises and prevents the valve from closing (aka power loss).

Oil splash. Try doing this same technique on a Corvair.... on your back.

Sherwood

My friend is trying to get a small block running right and he came accross this procedure. Seemed crazy to me. The rebuilt engine had some of the rockers eaten through by the valve stems only after 2000 miles. Some rockers were way off center without any hope or guide to keep them in place. I'd never would have believed that such a poor design keeps these engines running. One of the lifter rods was bent.

How does he know if he has hydraulic lifters? I think the block came out of a 74, went into an 86 Chevy S10 side step.

It should have hydraulics. that was standard for 74. as far as rockers being off center, could be bent pushrods. Bent rocker stud? Are the pushrod guide plates installed? It sounds like a bad rebuild.

I wouldnt say its a poor design, the SBC is one of the most reliable engines ever made.

Well I've been suspecting a bad rebuild all along. The engine leaked oil like crazy and though he worked on the valves several times, they were never right and always came loose after that adjust while it runs crazy procedure. The pushrods were all straight to begin with as he rolled them on glass to check. But, there were no guide plates that I can remember and one of the rocker bolts broke partially off, another was loose. He is going on his third set of rockers, the next one better than the last. Now a couple of the valve stems are worn down too far maybe and the heads may need to come off.

What do those guide plates look like?