Wondering if any of you guys know the max lift on these heads. The springs p/n is 12551483. I want to put a xe274 cam in my car with these heads and right now I have 1.6rr on it. I calculated it out and it comes out to .519 on intake a little less on exhaust.

 

The stock springs that came on the FastBurns are rated for .525 lift.

According to my Pace Parts catalog, GM springs # 12551483 have an installed height of 1.78" and a solid height (coil bind) of 1.22" leaving (1.78 minus 1.22) .560" clearance.

Subtract .040 needed spring coil cleance leaves a maximum lift of .520".

Subtract .030 needed spring clearance leaves a maximum lift of .530".

My opinion is your setup is ok but barely adequate.

The heads will flow cfm numbers way above these springs capabilities.

jms

*Incidently, I have FastBurns and the springs checked out at these numbers. They will not stay on the heads because the ZZX cam I'm installing needs more clearance.

 

Thanks for the quick reply, I'll go ahead and try it sounds like it should workout alright. Next thing I have to get is the pushrod length. I just read an article from carcraft (old one) and they show how to do it without any checking tools. Going to do it like they did so its right the first time. I already had to get longer pushrods for the heads. Do you think a degree wheel for the cam is needed or should I just put the cam in TDC?

 

Checking what the cam is supposed to be never hurts, but to do it correctly, you will need more than just a degree wheel.

Visit Compcams or Crane for details on degreeing a cam.

jms