Pushrod Length for Dummies

[turbojimmy]

Okay,

I read the archives but I still haven't found a concise, easy to follow explanation for how to measure pushrod length. I need to take my valve covers off to retorque my heads so now is a good time to see if I can eliminate the racket coming from my rockers.

First, I have a 218/212 roller cam with stock rockers. Should part of this excercise be moving to roller rockers? If so, which ones?

Second, I need to know how to measure pushrod length. Let's pretend that I don't know what preload is or how to measure it (because I don't). The engine is in the car and the intake is installed so I can't see the cam lobes.

The reason I need to do this is because I have about 160 miles on a fresh rebuild and the racket from the valvetrain just can't be right.

TIA,
Jim

 

[86 TR]

Your not alone!

I have a fresh engine also and went with a 212-206 roller from Weber. I used a adjustable pushrod from my local machine shop to get the correct preload.

Im using Harland Sharp 1.55 ratio roller rockers on my setup and its freakin loud too! Ive adjusted the preload to 1/2 turn, then 3/4 turn to no avail.

I guess I should just learn to live with it because the engine has roughly 300 miles on it and its been full throttle 10 times already and everything looks good.

IMHO I would go with roller rockers for piece of mind because the stock rockers might not holdup to the spring pressures of the roller cam. But the expense of them depending on your budget will decide that one.

I would check with whoever built your engine and see if you could borrow a pushrod length checker. Do you have the RJC rocker arm supports? You can also get one from summit or other vendors.

To correctly measure pushrod length make sure the cylinder your checking, I usually check #1 that both valves are closed and the engine is at TDC on that respective cylinder. Then move the pushrod with your fingers up and down adjust the pushrod until you can't move it up and down anymore. Now your at zero lash. Turn out the pushrod 1/2-3/4 turn more and then remove it and measure. Then get the pushrods you need.