I need to buy some new pushrods, some nice ones since the regular
hardened ones have given me a problem (http://web.camaross.com/forums/showt...hreadid=170125).
Well Comp offers a set that is 7.150 in length for milled heads vs.
7.2 stock. My heads are not milled (yet) but I am using an impy
gasket so I'm already .020 too long with the stock length, right?
Now, I may pull one of the heads this winter for an unrlated issue and I was thinking of pulling both so they could be milled for a little more compression. Would it be alright to run the shorter ones for now in anticipation of having the heads milled?
According to the math they would be .030 too short where the stock ones are currently .020 too long. Even milling .005 would make it and even .025 too long or short depending on which pushrod, so milling anymore than that seems like it would favor the shorter pushrod. AFAIK this is only to correct valvetrain geometry and there is no rr/valve spring clearance issue (CombinationMS stock dia springs and CC roller rockers) but this is where someone else may know differently.

 

I suppose you can estimate the proper length, however if they are not the correct length your geometry is certainly going to be off accordingly, which will result in less than optimum power. I would think that running them too long with improper length would result in improper wear marks on the valves tips, however I don't know if this is damaging in the short run.

The proper way, of course will be to use an adjustable push rod and set the correct length when you get your heads milled and then get the correct length solid rods. JMHO

 

Don't assume anything. The correct way to do it is to use an adjustable pushrod length checker as mentioned above.
I had a small base circle cam and a decked block, when I checked it turned out that the ideal length was 7.200".
You can get this tool from comp under pn 7702-1 for around $25.

 

Ah, OK I expected that at some point. This is bench racing so to speak. I guess I should have asked who is running the 7.150 pushrod? And whats your combo that resulted in needing this?

 

Have to measure, can't be readily "calculated".

Rich Krause

 

When I bought my Crower 1.6 RRs, I got .50+ chromoly pushrods to boot. I didn't know any different then. And since the .50+ were recommended, I got them.

Since then I have had the heads done, as well as having to get a new shortblock (which required having the heads removed again.) And since the mech. has never mentioned anything about lousy geometry, I assume that the .50+ longer rods are doing ok.

If I detected incorrect contact between RR and valve stem, myself, I would use the adjustable rod to get it corrected.

So, again, in your case, just taking a WAG is not, in my opinion, the best method.JMHO