Pushrod Lenth

[Jas89TTA]

I got a set of adjustable pushrods for my car and can I intall them with out removing the intake? I belive my pushrods in there now are't the correct length. Also what's the procedure for measuring for the correct length pushrods. THanks

 

[Lunkan]

When I asked on the maillist earlier, I was directed to http://www.gnttype.org/techarea/engine/pushrod.html

/Andreas

 

[Razor]

It has to do with preload thats applied to the lifter.

So my way of adjusting is I spin the motor until the exhuast valve for the cylinder I want to adjust cracks open, then I go and find zero lash on the intake valve. You then based on the cam mfg set the preload by setting length on the pushrod. Most will be like .035-.050 thou. To set the exhuast valve, spin motor over until the intake opens then closes.. when it closes..set your exhuast. Repeat for all cylinders.

My car I set them to 1/2 turn past zero, but have fine threads on my poly locks.

Guess you know why I went with roller rockers

 

[83ttypecooled]

lifter preload

Hi,
Set them at .060 preload,a good general number that shouldn't cause trouble. If you like adjustable pushrods, you will like roller rockers more!

 

[89ICBM]

Originally posted by Jas89TTA
I got a set of adjustable pushrods for my car and can I intall them with out removing the intake? I belive my pushrods in there now are't the correct length. Also what's the procedure for measuring for the correct length pushrods. THanks

Howdy,

Yep, it is best to take the manifold off so you can see the lifters and cam. You can set both intake and exhaust on each cylinder this way. If you have a stock cam, the stock push rod length is 8.475". You can remove one with out taking the intake off and measure it or measure all, they will vary 2 maybe 3 thou. If they are in this range, they're ok. If you got your adjustables from J. Pearcy they are already set at stock length. The deal with the adjustables is the ability to set pre-load on each valve. The stockers actually vary on pre-load a good amount. The best way I found to set pre-load with the adjustables is to bring both lifters to the bottom of the cam, set zero lash the make 1 and 1/2 turns on the adjustment screw. Note, 1 full turn on the adjustment screw is 27 thou (0.027"). The tolerance for the lifter is 20 to 60 thou, no less than 20, no more than 60 so, 1 and 1/2 turns puts you right in the midle. If you want to get more precise, use the wire type feeler gauges and gauge under the retainer clip in the lifter. What I found is, when you set the legth and then lock the jam nut tight on the rod, you will gain an extra 2 thou of length.