5/16 or 3/8 push rods?

[Omie01]

Does anybody know if I should go up to 3/8" pushrods? My cam specs are .594 In-.611 Ex lift, and springs are double spring with a damper, 130lbs seated, open load 355lbs. Does the pushrod hole in the head allow for 3/8" rods? Any help would be appreciated!!

 

[Jeff73Mach1]

Go to 3/8ths with those pressures and lift. They will clear just fine.

 

[c9zx]

I had very slight contact between the 3/8" pushrod and the ends of the pushrod passage in the heads. It was just enough to "shine up" the surface of the pushrod. The block was decked and the heads milled with a .041 compressed gasket thickness. Rocker arms were Ford racing, valves were Ferrea +.100 length. There are a lot of variables here. I didn't want to pull the heads so I switched guide plates and used thick wall 5/16" pushrods without a problem but, I limit RPM to 6600 in the 408C. Just one experience, your combination may be different. Good luck with the build. Chuck

 

[MeZapU]

I've done both and not had any issues, but is always advisable to check clearances due to a myriad of variable build tolerances.

 

[Omie01]

I will double check everything when I get it back, I actually have a performance engine builder building the long block. We sat down and discussed my build for over 2 hours so he's very familiar with what I want. Not to mention he is a Ford guy. I actually bought the block from him!!