Checking Rocker Geometry

[red94fiveo]

OK, so I'm doing the headswap this weekend and the only thing I couldn't find a lot of info on is setting up/checking rocker geometry. Everyone says to make sure and do this, but no one ever seems to say what is involved with this. Someone wanna enlighten me?

 

[Last5.0]

you using pedestal (non adjustable) or stud (adjustable) mount rockers?? Basically, when you install the rockers they need to be adjusted to a certain torque within so many turns after zero lash. If this isn't achieveable then you have to either get different sized pushrods or shims. Stud mount rockers are adjustable and alleviate much of this problem.

 

[VibrantRedGT]

First off we don't know which type rockers you are using (Stud or Pedestal). Next go to Crane's website and print out the instruction for which ever type you are installing. Lastly do it about 5 times before you bolt on the valve covers.

 

[Killercanary]

He's talking about geometry, not valve lash. I just made a reply on this here in the last 2 weeks or so... but anyway the best and easiest was to check it is to do it with the motor out of the car as its hard to see the alignment of the rocker, valve and pushrod. Basically you need a dial indicator setup on top of the valve. You need to measure from 0 lift to max lift, then go exactly half way between (1/2 lift) at this point the pushrod, rocker, and valve stem should all be at 90* to one another. You sort of have to draw an imaginery line through the rocker from the roller tip to the psuhrod cup to see if its at a 90* angle, this is nearly impossible to do with the motor in the car but with a mirror and patients you can do it.

When in doubt, contact Ed, he'll help you out more than you can imagine.

 

[Rootus]

To check the geometry, get yourself an adjustable pushrod in the right range, and then try it at different settings. Color the end of the valve stem with permanent marker, install the rocker, and turn the engine a couple of revolutions. Pull the rocker off and look at the area where the ink was worn away by the roller, and then try again with a different length. You are looking for two things, 1) the narrowest sweep, and 2) centering of the sweep. In that order (#1 is more important than is #2). Comp cams has a nice description on their web site of what you're looking to see. An adjustable length pushrod is inexpensive.

Dave

 

[CivicEater]

I have the Trcikflow package with pushrods included so they are pre-measure....it also comes with 1.6's.....Do I still need to check the geometry?

 

[Rootus]

It costs nothing to verify, so I'd at least do that. But since everything is in a package, they're probably just fine.

 

[red94fiveo]

I just got a response from Ed and he helped out a bunch. Thanks also for the advice Dave and Paul. BTW - Taking the engine out is really not an option for me right now, but from the description Ed gave me it should work with the engine in the car.

BTW - They are stud mount rockers.

 

[final5-0]

This is mine. Maybe it will help.

Later
Grady

 

[94DreamGT]

I just got a response from Ed and he helped out a bunch.

Why don't you share the response then as it could probably help out other people as well.

Copy & Paste is a wonderful thing

 

[red94fiveo]

Yeah, that wold be a good idea, should have done that earlier. Anyway, here is Ed's response:

"Install the solid roller lifters.
Paint the top of the valves with a black permanent marker.
Adjust the valves as normal with no preload.
Turn the engine over a couple of times.
Remover the rockers and see where the swipe mark is.
The roller tip will wear the mark off a little.
The wear or swipe mark needs to be in the middle of the valve. "

Only one question, what does he mean by 'adjust the valves as normal with no preload'? Thanks.

 

[Rootus]

Only one question, what does he mean by 'adjust the valves as normal with no preload'? Thanks.

I screw down the adjusting nut until it hits zero lash (you can tell by spinning the pushrod with your fingers while you're tightening it down, when it gets to zero lash you'll feel drag on the pushrod), and then I turn it 1/2 turn past that point and set the lock.

Dave