Pushrod diameter

Shaffy · Post by **Shaffy** » Sat Oct 08, 2005 12:43 pm

Have a solid roller @ 252/262 640ish on both sides, springs are 260 on the seat and about 650 over the nose.

Will a Manley 5/16" .080 pushrod hold up?? 6800rpm max

Im using a std valvetrain on AFR 277 heads.. I cant get a 3/8" in there to my liking with std pieces.. will someday upgrade to shafts and offsets, but for now, this is what i have to work with and would like to use w/o spending anymore $$$..

Thanks guys, want to hear what you have used.

la360 · Post by **la360** » Mon Oct 10, 2005 3:59 am

I know of a couple of combinations that have gone faster with a pushrod upgrade( 5/16-3/8) Personally, I would run 3/8 as a minimum which what you're running.
AL...

Joe Mendelis · Post by **Joe Mendelis** » Mon Oct 10, 2005 8:06 am

What is the seat to seat timing? The lobe design is more important than the duration @ .050 for figuring how nasty a lobe you have. You could have a 255@050 TK lobe that is 283 seat to seat. You will hurt stuff in a hurry with a lobe like that turning rpm with a 5/16 pushrod.
If you have a weaker lobe like a street lobe you may have no trouble with it. For example; you have the same duration @050 as a TK lobe, but your seat to seat timing is 300 degrees. That is a pretty gentle profile that will get you a lot more rpm with stock type parts. More spring pressure is not always better.
There are other things to look at as far as the lobe design goes, but the easiest one to get a general idea is the 50 and seat timing.
If you are running to 6800 you shouldn't need 260 on the seat if you have good springs and your cam isn't overly radical.

Joe Mendelis · Post by **Joe Mendelis** » Mon Oct 10, 2005 8:10 am

Your real question was whether or not your pushrods will hold up? Maybe. I have seen 260 on the seat using hi tech 420 lobes and turn 7500 with not much trouble. Pushrods held up fine.(5/16)