Proper way to determine push rod length?
Thread Starter
Racer
Joined: Aug 2002
Posts: 366
Likes: 0
From: Pataskala OH
Proper way to determine push rod length?
Please school me on how to determine proper push rod length with a BBC 7/16 stud, aluminum Performer RPM heads, hyd roller cam and Crane gold roller rockers. I bought the adjustible length push rods for sizing purposes. How far down on the stud is the rocker arm supposed to be? How do you determine the proper angle? Thanks!
Racer
Joined: May 2000
Posts: 386
Likes: 0
From: Niedernhausen, Germany
Re: Proper way to determine push rod length? (zZArAZz)
The idea is to have the Rocker contact the valv exactly in the middle to prevent side-loads which would lead to premature guide wear.
In order to determine optimum length, apply some colour on the valve top of one valve (e.g. with a marker), then assemble and rotate the engine a couple of turns - if you use check-springs instead of the original springs, it makes it a bit easier. Where the rocker hit the valve can be seen by the remainders of the colour. With your adjustable pushrod, repeat until the rocker marks are in the center of the valve top.
Then get a catalogue and choose a set of length closest to what you have measured on your adjustable rod. With the length of these push-rod, try again (adjust you pushrod to the length of the available push-rod) to double-check.
NOTE: Push rod length can be measured in different ways! Therefore I recommend measuring your adjustable pushrod and then send a mail to the potential suppliers, describing how you measured and asking for an offer to your required length..
Regards,
Thomas
In order to determine optimum length, apply some colour on the valve top of one valve (e.g. with a marker), then assemble and rotate the engine a couple of turns - if you use check-springs instead of the original springs, it makes it a bit easier. Where the rocker hit the valve can be seen by the remainders of the colour. With your adjustable pushrod, repeat until the rocker marks are in the center of the valve top.
Then get a catalogue and choose a set of length closest to what you have measured on your adjustable rod. With the length of these push-rod, try again (adjust you pushrod to the length of the available push-rod) to double-check.
NOTE: Push rod length can be measured in different ways! Therefore I recommend measuring your adjustable pushrod and then send a mail to the potential suppliers, describing how you measured and asking for an offer to your required length..
Regards,
Thomas
Le Mans Master
Joined: Mar 1999
Posts: 6,744
Likes: 1
From: delmont pa
Cruise-In I Veteran
Cruise-In II Veteran
Re: Proper way to determine push rod length? (zZArAZz)
manley sells a special tool to do this,less than $20. check your local speed shop or summit :chevy
[Modified by clem zahrobsky, 6:07 PM 3/14/2004]
[Modified by clem zahrobsky, 6:08 PM 3/14/2004]
[Modified by clem zahrobsky, 6:07 PM 3/14/2004]
[Modified by clem zahrobsky, 6:08 PM 3/14/2004]
Tech Contributor
Joined: Aug 1999
Posts: 14,380
Likes: 6,391
From: At my Bar drinking and wrenching in Lafayette Colorado
Re: Proper way to determine push rod length? (zZArAZz)
CompCams has a great tutorial on their site. Go to:
http://www.compcams.com/catalog/278.html
http://www.compcams.com/catalog/278.html
