1badasZ

im not anywhere near advanced enough to check geometry n stuff to find the exact pushrod length. for what i've done do i need stock length, longer or shorter? stock block, heads milled .010, crane springs, impala head gaskets, and comp extreme 230/236 .544/.555 with 1.6 rr

henryz28

Stock is 7.2" lloyd told me to run 7.1" if I did not want to measure the pushrod length. So I would think you would be good to go with 7.1" pushrods if you don't want to measure the length.

MachinistOne

If you're not capable of checking for PR length you shouldn't be touching the motor, it's as simple as that.

The procedure is cheap and easy, and there's plenty of write-ups on the internet of how to do it properly....no excuses

You really want lost lift and quickly worn out guides by possibly getting the wrong PR length?

henryz28

PR length is something that you need to check to get the EXACT length. Use an adjustable PR checker and start at 7.100" and adjust the length until you get the wear pattern most centered in the valve. Go .050" shorter and watch the wear pattern move. If it gets worse, go .050 longer. It could be anywhere from 7.00 to 7.250 depending on everything done but a 7.100" (Trik Flow 21407100) is what I suggest for people that do not know how (or do not wanna take the time) to do this.

The following is a method of verifying proper valve train geometry. After you have estimated the required pushrod length using a Pushrod Length Checker, use this method to verify that the valve train geometry is correct (using the rockers you are using in your engine):



1
The first step is to install a solid lifter and an adjustable pushrod. Mark the tip of the valve with a marker



2
Install your rocker arm and set it up with zero lash.



3
Rotate the crankshaft clockwise several times. Remove the rocker arm. The contact pattern of the rocker tip will be where the marker has been wiped away from the valve tip. The pattern should be centered on the valve tip, and as narrow as possible. If it is not, experiment with varying the pushrod length to yield the best pattern.



4
Pushrod Too Long: Notice how the pattern is wide, and shifted to the exhaust side of the valve tip.



5
Pushrod Too Short: Notice how the pattern is wide, and shifted to the intake side of the valve tip.



6
Pushrod Length Correct: Notice how the pattern is narrow and is centered on the valve tip.

That is my message from lloyd, but I did not post the pics

Guest47904

This is the best information available

http://www.compcams.com/Pages/417/va...-geometry.aspx

In a nut shell, you want the contact to be as close to the center of the valve the entire time.



Start with the rods you have and check it. Then decide if the "tester" you need is longer or shorter based on the movement of the arm.

1badasZ

Ok sounds easy enuff just wasn't sure how to go about it. Can I use 7/16 studs and guide plates on my heads without having to machine anything?

bowtiedad_z28

Yes you can.

bw_hunter

Yes, you can. the stock 3/8" studs are7/16" in the head...