Valve Lash - Team Camaro Tech
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post #1 of 16 (permalink) Old Nov 19th, 00, 09:08 PM Thread Starter
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I read the reference article about how to adjust valve lash. Is it really that simple for a hydralic lifter setup? ...tighten until all slop is out of pushrod and then tighten 1/4 turn? There is no need to measure clearances? I rebuilt a 350 not to long ago and it's time to retorque the heads and adjust the valves....just wondering if that's all the precision that I need when I do this.
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post #2 of 16 (permalink) Old Nov 19th, 00, 10:31 PM
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Yes, that's pretty much all there is to setting lash. Just be sure that the cam is at 0 lift on its base circle. I still like to adjust the lash with the engine running though, just to make sure. I pull one valve cover at a time and start the engine. Back the rocker nut off till it starts clicking, then tighten till the clicking stops and give it another 1/8-1/4 turn.
High quality head gaskets such as Fel-Pro don't require retorqing. Are you sure yours do?

[This message has been edited by Hals73RS (edited 11-20-2000).]
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post #3 of 16 (permalink) Old Nov 20th, 00, 10:39 AM
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There is a lot of leeway in the adjustment of hyd lifters, I doubt yours need adjusting.

I like to back them off until they click, turn them down until they stop and do that to all valves on one side. Then turn off the engine and crank down on each adjuster one turn.
This saves a lot of time as usually you have to wait for the lifter to equalize and bleed off the excess oil or the engine will die.
By turning them down while the engine is stopped, they bleed down and re adjust faster.

Many guys have had problems adjusting to zero lash while the engine is stopped. Some twist the pushrod to determine zero lash but if there is lube on the pushrod you may actually be preloading the lifter without knowing it and get the valves too tight.
I like to just lift up and down on the rocker tip and can tell easily when there is no lash. Then turn down one turn from there. And there is no oil mess with the engine stopped.

If you have the anti pump up hyd lifters, you can only go a half turn and some only a quarter turn.
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post #4 of 16 (permalink) Old Nov 20th, 00, 01:16 PM
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I've heard the suggestion that, to avoid pumping up stock type lifters above 5500 rpm, you just tighten 'til the noise disappears and basically leave them there, or maybe an 1/8 of a turn past that, rather than the full 1/4 to 1/2 turn for the recommended .020 to .040 lash. This gets rid of the clatter, but prevents valve float at higher r's.

Any thoughts? (Before I fire up my new engine??!! I spun the pushrods as I adjusted the nuts 'til I felt the slightest resistance, and then gave another 1/8, or slightly less, of a turn.)

I've talked to mechanics who say they do all adjustments on a non-running engine, and maybe not even hot - that it just doesn't matter that much. Of course they're usually working on someone's grocery-getter. All the components involved are steel or cast iron. The diffences in coefficients of thermal expansion (which would cause the change in clearance) should not be that great.

Also, is there any good way to avoid an oily mess when setting lash on a running engine? I've only been involved in the process on a running engine once (watching someone else do it) and there was oil squirting everywhere.
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post #5 of 16 (permalink) Old Nov 20th, 00, 05:06 PM
 
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They do have clips that clip on so the oil doesn't splash all over. I haven't tried them thought. If
anyone has let us know how good they work or not.
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post #6 of 16 (permalink) Old Nov 20th, 00, 08:03 PM Thread Starter
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Well I adjusted the valves...there were a couple that were loose after retorqueing the heads. I tighten them down until I could just barely spin the pushrod and then went another 1/4 turn...hope I don't screw up anything. Thanks for the responses guys.


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post #7 of 16 (permalink) Old Nov 21st, 00, 06:09 AM
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Dan,

I don't think you want to tighten the adjusting nuts until the pushrods will barely spin - there is a substantial amount of freeplay in the lifters (close to .1 inches - maybe more) that you may be removing. By the time you tighten 'til the pushrod will barely spin, and then tighten a 1/4 turn more, your lifters may be sitting off the seats from the get-go. They should spin extremely freely until you make contact, and then you should stop tightening as soon as you feel a CHANGE in resistance to spinning (rather than complete resistance to any spinning). When I did mine, I noticed that when I got close I could put enough pressure on the rocker with the socket to induce a little resistance in the pushrod - so as soon as I felt a little resistance I lifted off the ratchet and confirmed that it was pre-load dragging on the pushrod - not just my heavy hand on the ratchet forcing the rocker down. But you could tighten it a long ways beyond slight resistance and toward no turning which would probably get you way over-lashed.

I'm no expert - I've just done it for the first time myself, and still haven't gotten my engine dropped and fired it yet - so I don't know what my result will be. Just a few thoughts. Maybe someone else has better advice - or thinks I'm all wet on this.

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post #8 of 16 (permalink) Old Nov 21st, 00, 11:16 AM
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Dan,

I've done it with clips and they really worked not letting any oil all over. The only problem is that if they are loose they clatter, disturbing you from hearing the rocker arm well.

Jorge
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post #9 of 16 (permalink) Old Nov 21st, 00, 04:37 PM
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an old trick for containing oil when adjusting valves when the engine is running- cut out the top of an old valve cover right above the adjustment nuts and place it on the head ,start engine and go after it

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post #10 of 16 (permalink) Old Nov 22nd, 00, 09:37 PM Thread Starter
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Well...I guess I'll pull the vavle covers and check again. I should've mentioned that I have Erson roller rockers...if that makes a difference. Even from the machine shop some of the push rods seemed awfully tight. Thanks for all the responses. I'm glad I don't have solid lifters....
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post #11 of 16 (permalink) Old Dec 9th, 00, 07:52 PM
 
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dont say that cause i feel solid lifters are more responsive. they dont have the hydraulic lifter slack.
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post #12 of 16 (permalink) Old Dec 10th, 00, 04:34 PM
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I also have solids. Part of my therapy program adjusting the valves!
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post #13 of 16 (permalink) Old Dec 11th, 00, 03:34 AM
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I have solids too. Nice part is they always make noise, so you can tell yourself they are not really loose!

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post #14 of 16 (permalink) Old Dec 11th, 00, 06:36 PM
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Guys, where do you get the "clips" that someone mentioned?

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post #15 of 16 (permalink) Old Dec 12th, 00, 12:32 AM
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Summit has them on page 48 of their newest catalog. Part # SUM-140355 for $9.95....while supplies last!!
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