I saw this mentioned in some old messages, in particular, by Stephen87IROC and FastBroker, but could use some more info on it!

We have to adjust the valve lash for that 2.8 I'm working on. The books all say to spin the pushrod as you tighten the nut, until the pushrod stops spinning, then go 1/2 turn more... but I'm such a strong guy (grin) that it might take a lot of twist on the rocker arm nut to stop me from spinning the pushrod!

So, how would I do this with a dial indicator? Or, should I not bother with it, and just go for turning the pushrod? I read also (by searching here) that I could try jiggling the pushrod up & down, and 0 lash is when the pushrod won't move up/down anymore.

Thanks!


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-Tom P (Hot rodded 1986 Firebird 2.8l) from http://www.f-body.net/mailbag/3rd/3rd_mailbag.html message boards
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Try doing the twist thing to all of them and go 1/2 turn more. THEN, start the engine and adjust them individually. Loosen up the nut until the rocker starts to clatter or "click" then tighten it until it stops, then go 1/4 turn more. Do that to all of them and you should be good to go.

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92 Z28 5.7
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Well, problem is, this engine's on the stand right now. I'd like to nail valve lash perfectly, so we can just "finish" this engine, pull out the melted one, and put this one in it's place...

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-Tom P (Hot rodded 1986 Firebird 2.8l) from http://www.f-body.net/mailbag/3rd/3rd_mailbag.html message boards
---Think your car could be pic of the week? Visit http://www.f-body.net for details!

 

Tom, Dont take this the Wrong way...

But as Much as we all love the 2.8L, If you kentucky fried Yours, seems like a Perfect Time to Swap For a V8.

Why Go to all the trouble To rebuild and Swap In another 2.8L ?







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I'm not answering that. If I wanted to hear crap about that, I would've asked.

[edit] This isn't being done to my car. My 2.8 is fine.

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-Tom P (Hot rodded 1986 Firebird 2.8l) from http://www.f-body.net/mailbag/3rd/3rd_mailbag.html message boards
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[This message has been edited by TomP (edited March 09, 2001).]

 

What you said above will work. Zero lash + half a turn. To get it perfect, you can do it while it's running. But it's not usually necessary.

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82 camaro--original steering wheel, brake/gas pedals, seats--everything else modified
82camaro

 

If you tighten the adjusting nut until the pushrod stops spinning, the add additional turn(s) as preload, you will have tightened the preload much too much.

I don't which reference manual is telling you to do it this way, but every manual I've seen on this procedure is to tighten the nut while twisting the pushrod only until slight resistance is felt; not until the pushrod can no longer be twisted.

What you're looking for is zero clearance and from that point you set the preload, which will depress the lifter plunger somewhere between .030 and .060.

I suppose you could set it a dial indicator on each rocker and measure just how many turns it takes to cause the lifter plunger to depress the desired amount, but you still have to be absolutely certain that you begin at zero lash. Besides it would be a real time consuming not to mention a PIA.

Of course, folks have different methods they prefer, so choose your poison.

I typed up a file of the procedure I use and recommend, so if you're interested and taking a look I can email it to you.

Hope this helps.

Jake

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1986 Corvette Coupe, 415 CID, Edelbrock 6073s, ZZ9

 

Minimum lash runs .020 to a max of .060. You can set this with a dial indicator if you are careful and set it up right on the engine. Put the tip in the lifter next to the pushrod, and make sure it isnt hitting anything but the pushrod cup in the lifter. Then you just tighten up the rocker arm until the indicator just starts to move, thats zero lash. I would set the lash from that point at about .030. You might have to move the indicator after you find zero lash to the end of the rocker over the pushrod, depending on what kinda tip is on your dial indicator. I also left out the step of making sure the lifter is on the base circle of the cam, but just about any manual or other posts here have been through that procedure.
You can also get pretty close by closely watching the pushrod cup in the lifter for when it just starts to move, and given the tolerance you will be close enough once you tighten it down. This procedure is much more accurate than adjusting while the engine is running, and the only way you will have noisy rockers after doing this is if there are worn/damaged parts somewhere.

[This message has been edited by madmax (edited March 09, 2001).]

 

I don't have any tips for the dial gauge... guess I can't put the tip in the lifter next to the pushrod then, eh? I'm not sure if the lifters poke out enough thru the intake manifold to get at them, either.

JakeJr if you could send me that file, I'd appreciate it!


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-Tom P (Hot rodded 1986 Firebird 2.8l) from http://www.f-body.net/mailbag/3rd/3rd_mailbag.html message boards
---Think your car could be pic of the week? Visit http://www.f-body.net for details!

 

Everyone else explained how to do the adjustment with a dial gauge however finding zero lash is almost trial and error by spinning the pushrods.

The best way I found to get the starting point of zero lash is to use a feeler gauge. I put a .0015 feeler gauge under the rocker. When you have a slight drag on it, you are just about to zero lash. It's close enough. Then use the dial gauge to set them between .020 and .030 (usually 1/2 turn). You could use a thicker feeler gauge also. Use a .010 feeler gauge. Then just add an extra .010 to the adjustment on the dial gauge.

I think that's more the info you were looking for.

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Tom,

Steven is right about dead on target with the solution.

Remember that even the cheapest hydraulic lifters have a pintle travel of at least 0.080" to compensate for valve train wear. If you are adjusting by the "half-turn" method, that half-turn is roughly the equivalent of 0.020". If you are using a precision instrument to measure the half-turn of the wrench, you might get it within 0.002" of being "perfect". It just doesn't matter that much, since the lifter will compensate for a lot more lash than that. If you are afraid that your adjustments are a little too deep, remember that you can go up to another 0.040" before you start bottoming the lifter (or one complete turn MORE). As long as all the lash is taken up, and the lifters have been primed with oil, take the nut down until there is no more lash in the push rod by using your "up-and-down" method instead of turning the push rod, then adjust the additional ½ turn. At worst, the adjustment will be a little on the loose side, which I tend to default toward to prevent valve float from pumped-up lifters at higher RPM. If in doubt, go to 3/4 turn and forget it.

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Later,
Vader
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