[Strokd66]

Does anyone forsee having .400" to short pushrod length on a hyd roller cam BBC having any effect on performance?

 

[F1 Speed]

:yes: Yes ! Think a minute or two what the push rods do.

 

[66 BRONZE]

Wow, just wow!!!!!! Give me air/fuel!!!!!!

 

[superstocker72]

its gonna wear the guides out ect..., your geometry will be way off. measure the p/r length and get the right p/r

 

[GRN69CHV]

.400" is a lot, how did you determine it?

 

[Strokd66]

Ok here is the deal.....When I first built the engine I was under the understanding that you want to center the travel of the rocker arm on the valve stem. I had no concern of how wide the pattern was. It is to my understanding now, that you want the narrowest pattern. I found some pushrods that where listed for BBC hyd roller cam applications. So I compared them to mine, .400" longer on the exhaust for starters. So using my pushrod length checker I did a pattern check with both. The ones I currently have in the engine provide a "centered" pattern, but it is really wide. The .400" longer pushrod provides a very narrow pattern, but favors te exhuast side of the stem.

 

[Euell Florett]

Don't use those pushrods! :noway:

 

[Strokd66]

Don't use those pushrods! :noway:

Well the short pushrods have been running in the engine for two summers now...

 

[GRN69CHV]

What heads are on the motor? Do you know valve length? It is very common to move the pattern to the outside, just don't want to get too far out. You may have to try a different rocker, these do vary in geometry from manufacturer to manufacturer.

 

[Strokd66]

What heads are on the motor? Do you know valve length? It is very common to move the pattern to the outside, just don't want to get too far out. You may have to try a different rocker, these do vary in geometry from manufacturer to manufacturer.

Edelbrock Victor Jr part #77489

 

[GRN69CHV]

Unforetunately, no way to know w/o measuring. +.200-.250" is common.

 

[steelcomp]

Depending on who's hyd rollers you have, the pushrods already start getting real short as compared with stock. The shorter the pushrod gets, the worse the geometry gets even when the pushrod is the right length, so the last thing you want is pushrods that are any shorter than necessary.
Look into geometry at mid lift and learn how to correctly determin rocker geometry and pushrod length. Those pushrod "checkers" you buy don't take into consideration a lot of variables.

 

[Strokd66]

Depending on who's hyd rollers you have, the pushrods already start getting real short as compared with stock. The shorter the pushrod gets, the worse the geometry gets even when the pushrod is the right length, so the last thing you want is pushrods that are any shorter than necessary.
Look into geometry at mid lift and learn how to correctly determin rocker geometry and pushrod length. Those pushrod "checkers" you buy don't take into consideration a lot of variables.

According to the article written by jim miller seems pretty simple to determine pushrod length. Think i'm gonna try that