Air_drewdy

Hey guys im wondering how do i check my valve lash? I know how to adjust it and make sure it’s good the push rod should not be loose correct? And then my next question is if i have to adjust them since my lifters are already primed can i still set the preload? Once i adjust it to obtain 0 lash how can i set the preload on already printed lifters?

thanks

4-vettes

Hopefully you have a service manual. Valve adjustment is covered.
basically, when the lifter is on the heal of the cam. Adjust rocker to zero lash. Then 1/2 turn down. Done.
Now, the critical part is making certain that the lifter is on the heal of the cam. And knowing how to feel zero lash. There are a couple ways to do this, remember when done you have to do all 16.
I personally like the quarter turn method. But I have 90 degree marks on my flywheel.
Jebby has posted a fool proof method he likes on here a number of times. Perhaps you could search older threads on this topic or perhaps he will chime in.
In the meantime, get yourself a service manual. It's full of instructions on how to do everything on your car. And unlike YouTube, the factory actually knows!

4-vettes

I posted this up on here awhile back, and the guys all laughed at the "Engine off". Yes, that's kinda dumb. But this method works well for a beginner. And you'll see that it flows from one valve to the next with realitivly minimum turning of the crank. Remove all spark plugs. Learn how to rotate the pushrod between your finger and thumb to feel when the pushrod is loose, and when you reach zero lash.
turning your crank in the direction of rotation, follow this chart.


adjust to zero lash, then 1/2 turn down. The lifter will bleed back. No worries if they are full of oil. The lifter will bleed back long before you get everything back together.

HeadsU.P.

O.P. already asked this question in another thread.
And the answer is still the same.

Watch a video on YouTube. Just pick one, any one, as long as its old Chevy the vid will show you step-by-step.

leigh1322

And when you mess it up, cause you are in a hurry it runs really... really bad. Like 3-4 cylinder bad.

Moral is: DO NOT be in a hurry!

lionelhutz

Yes, they will be. If you can't spin the push rods and wiggle the rocker arms then you've gone too tight.

Jebbysan

I use the firing order method and have for over 25 years. Why? Because it is very hard to screw up......
First off.....if you have the "pinch nuts" throw those in the trash and get a set of short Poly-Locs....because the Poly-Locs spin freely on the stud until you lock them.....this is important for how I do the "zero lash" before setting the pre-load. Second, make 90 degree marks from TDC on the harmonic balancer....at 90, 180, 270......with a Sharpie.....
Now put the engine on #1 TDC. You can now adjust both rockers on #1 TDC. Spin the Poly-Loc with your fingers until you start approaching zero lash at the pushrod......as you are spinning with your fingers you feel a slight resistance as the lash is taken up and it starts to push the plunger in the lifter down.....this slight resistance you fell in your fingers is true zero lash...... The lifters HAVE to be dry internally for this.....if they are full of oil they will not plunge. From zero lash turn 1/2 turn more and Lock the Poly-Loc.....NOW, go to #8....the first black line you marked on the balancer......and perform the same procedure.....each 90 degree mark is the next cylinder in the firing order at TDC of that cylinder. When you get to #2....and set it....you are DONE!
The reason I like this method is it almost ensures that you do every cylinder and is easy to pick back up if you get distracted.....the Poly-Loc in the fingers takes a little practice feeling it out but once you do it is best way possible to know zero lash. You can spin the Loc in your fingers back and forth tightening and loosening and bit until you find the sweet spot......
For solid lifter stuff.....you do the same procedure but instead of shooting for zero, you shoot for an easy slip of a feeler gauge.......which is for all purposes, "zero" on the feeler gauge.....solids are more tricky as the lash will move some as you tighten the Poly-Loc......takes some practice.....
There are other ways to lash valves.....this is mine. Never had to go back and redo an engine ever in over 200 builds.....

Now lets talk about setting valves while running......There has never been a factory procedure for this.....it is messy, inaccurate and 100% can't be done with solid lifters.....besides the fact that it is 100% unnecessary!

Jebby

lionelhutz

I read once that you could turn turn all rockers to zero lash, turn the engine 45 degrees and set zero again and just keep repeating that for 2 revolutions. During this time never back any off after rotating the engine so if you find it tight then leave it. Then, after doing that for 2 rotations turn all of them 1/2 turn and it's done.

The theory is that you'll get all 16 down to zero lash as you go then at the end you set the preload by turning them all at the same time. 45 degree turns ensures every lifter will be adjusted on the base circle at some point in the 2 rotations. There is no need to start at TDC or mark the balancer or follow a firing order.

I've never tried it, but it would avoid having to figure out TDC or follow a specific setting order so it could be an advantage for someone who rarely does it. When I think about it, someone with practice could slap the ratchet on the crank and turn with one hand while spinning down any loose poly locks with the other hand and be through it in no time.

randallsteel

truth!
tried it once and made a huge mess. And I didn’t feel confident with the result so I redid it the classic way anyways. Never again.