As a follow up to this thread: https://www.corvetteforum.com/forums...arm-issue.html, I'm setting lash but not sure if I'm doing it right.
When I hand tighten the polylocks on the rocker stud, the up/down movement of the push rod is gone (without socket tightening). But, if I grab the pushrod w/ 2 fingers and push down with some force, the rod will go down (I assume this is the action of the hydraulic lifters?).

So should I be tightening down to where I can no longer get up/down movement on pushrod using force, or without? If without, that means I'm only finger tightening the polylocks, then adding a 1/2 turn for preload. That seems really loose as all the vids I've watched it seems they're really cranking down on the polylocks with a socket.
The twist/spinning pushrod method doesnt seem to work because it's easy to spin reardless of how tight the polylock is.

 

no, work on spinning the rod as you adjust,
just when you start to feel the slack is gone and the spinning of the rod is stopped....that is 0.
from there add your 1/4, 1/2, 3/4 turn lash as maker recommends.

 

Wiggle the rocker cup till it stops using minimal force, then follow the turn down instructions. I use less turn down than they say, but then expect the engine to run rough till the lifters bleed and adjust. When you turn down to adjust, the pressure will hold the valve open in most cases and it takes about a min or so for the lifter to adjust, then it should run smooth.
A bit of info here is that oil pressure enters the lifter thru a hole mid way down to pump it up and valve spring pressure will allow the lifter to bleed the oil pressure needed to adjust it. Simple.
I invented a lifter bleed off device to test aircraft hyd lifters that are expensive. I bought 20 and I sent about a dozen back to the engine manufacturer with a red tag. I was called and they talked to me for 1hr 20 min about my test equipment. They were impressed but their test was using finger pressure that could not be measured where my equipment measured using pneumatic pressure regulated to spec. Also tested the lifters in their operating range which the manual did not know exsisted.

Dom

 

I used this as my guide:Scott Shafiroff has over thirty years of involvement in both racing and race engine building. Currently the owner of Shafiroff Race Engines and Components.

Pat Musi got into racing in 1969 and along the way became a eight-time Pro Street Champion with over 40 years of engine building experience. Owner of Pat Musi Performance.

David Reher started building engines with Buddy Morrison in 1971 in the back of an auto parts store in Mansfield, Texas. Master engine builder Reher leads the Reher-Morrison Racing Engines company and has for almost 40 years.

We also checked in with Ashley Newman, Technical Advisor at COMP Cams to get a manufacturer’s perspective on setting valve lash. Newman is also an accomplished circle track racer that understands the real world, “get ‘er dun” attitude of pit area maintenance as well as the maintenance in a laboratory type environment.

Getting Started

Regardless of what you’ve heard, there’s no mystery to setting valve lash on flat-tappet cams. Whether you’re dealing with hydraulic or mechanical flat tappet cams, we’ve got the procedure that will make this very important task as smooth as butter.

Starting with rocker arm installation, check to make sure that the pushrods have been installed through the guide plate into the center of the lifter. COMP Cam’s Ashley Newman recommends that “all pushrods be pre-oiled or primed, through the pushrod holes.”

Begin by checking to make sure that all of the pushrods have been installed through the guide plate into the center of the lifter.

Next, apply a small amount of assembly lube to both the valve stem tips and the rocker arm’s pushrod seats. We’ve had great success with COMP Cams assembly lube and it has become a staple in the powerTV garage. Once the valve stem tips and rocker arm seats are coated with assembly lube, the rocker arms can be installed on the rocker stud. Applying a generous amount of assembly lube to the rocker arm ball, position it on the rocker stud with the flat side of the trunnion facing up. Double-check to make sure that the pushrods are seated correctly in the lifters and the rocker arm seats. Using this exact process, install all the rocker arms. Newman told us, “It is extremely important to install the rocker arms without rotating the engine because you can accidentally bend a pushrod without knowing it.”

Making sure that the pushrods are centered in the lifter cup is critical for setting valve lash.

Install the adjusting nut by tighten the nut “finger tight” to the point where the pushrod has no lash, but will still spin with your fingers. Repeat this process until all pushrods are seated and all rocker arms are installed.

Finally, it’s time to set the valve lash. Our experts have told us that the best way they have found is to set the lash, one cylinder at a time, in the correct firing order. Make sure that the dampener bolt is installed in the crankshaft, turn the engine over by hand in the direction of its normal rotation.

Setting valve lash on hydraulic lifters does not require a “feeler” gauge. The process is the same for stamped steel rockers (like the ones pictured) or roller tip rocker arms.

For Hydraulic Lifter Camshafts

When the exhaust valve just begins to open on the first cylinder in the firing order, adjust the intake valve by loosening the adjusting nut slightly while spinning the pushrod until you feel lash in the rocker arm. Tighten the adjusting nut until the slack is taken out of the rocker arm and pushrod. Lightly turn the pushrod with your fingers as you tighten the adjusting nut, and you should feel a point where there is a little resistance (this is called Zero Lash). Turn the adjusting nut ½-turn past this point, giving you optimal pre-load for the rocker arm, pushrod and lifter. According to Newman, “you should look for .030-.060 of preload in a typical hydraulic Lifter.” Follow this procedure by carefully adjusting each intake valve according to cylinder firing order.

When all of the intake valves have been set to the proper valve lash, you can adjust the exhaust valves. Utilizing the same procedure as with the intake valves, you need to turn the engine over until the intake pushrod moves all the way up and rotates just past maximum lift. Now the exhaust valve can be adjusted. When all of the intake and exhaust valves have been set with the proper lash, it is common for all the top engine builders to perform a double check by rotating the engine and checking each valve again, starting from the first cylinder in the firing order.

 

EOIC method has never failed me. Sure takes longer but its very accurate esp with solids.

Spinning the pushrod works fine BUT a few times Ive been caught hanging a valve open as the lifter depressed and the pushrod still spun, fooled me.
So if possible ck for up/down slack to be safe. Good to see someone print 1/2 turn, 1/4 and 1/8 turn nope.

 

The short answer is - no force should be applied down on the pushrod with your fingers. It is only a light feel. When there is no slack left WITHOUT FORCE - just casually moving the pushrod up and down till it stops, you are at zero. Add a half turn or so and lock it down. The tiny spring inside the lifter is what you will be compressing if you can force the pushrod down. If you are forcing it down, you are going past zero.

You still need to make sure the geometry is good and nothing is interfering but this will cover the lash adjustment.

 

You ca not get easier then this , Ignore every one and follow this video , I gave it to ya once already ..

https://www.google.com/search?client...bOtQaOmq2YBg36

 

The problem with videos is he can not feel anything. He watches and THINKS they are cranking down hard. Why? I don't know. He can't feel that.
O.P. Find an old mechanic to come over and show you. I could teach you in 2 valve adjustments, Here, feel this, Now, feel this. And then you would do the remaining 14 just fine.
Find an old guy like myself who's been doing it for 50 years to show you!

 

The lifter spring pushes back up, right? It sounds like you are doing it right. The poly locks make it that simple. You don't need to figure out spinning or lifting the pushrod. Just finger tight and you've removed all lash.

Check it this way. Grab the valve end of the rocker between your finger and thumb with one hand and lift it. Don't try to force it, just lift enough to hold it up and take out any slack that might exist. Then tap above the valve with a finger of your other hand. You'll hear a tick as the rocker hits into the valve if there is lash.

EOIC is an easy way to get to the right spot to set each valve.

FYI, you lock them down by loosening the nut about 1/16 turn and then tightening the set screw before tightening both the nut and set screw at the same time back 1/16 turn.

 

yes!

 

Appreciate all the help guys. Got it done, lash is set and it's running well. I had to re-do it twice. I was definitely cranking down too hard until I realized (as lionelhutz stated), that finger tightening the polylocks until they hit the trunion corresponds w/ zero lash. It got a lot easier after that epiphany.

 

Good to hear ya got it!

 

This is exactly how I do it.......the poly-loc should spin freely on the stud.....when it reaches zero...you will feel a slight resistance in your fingers as the pushrod starts to plunge the lifter.....this is true zero lash.....then 1/2 turn after.
I use the TDC method rather than EOIC method......for mild hydraulic cams, flat or roller......
For solid race cams I use the EOIC method......this method also has to be used on the old 30/30 cam because believe it or not......the valves are not 100% closed at TDC.

Jebby