On a 440 / 500 ci engine build with a set of cast iron heads using a Comp Cams Xtreme Energy .564 cam and a valve spring spec of 330 psi open @1.275 at .600 lift, will a stock push rod hold up. Also, how much run out is acceptable on a stock type 5/16 push rod.

The reason I ask is I checked the stock push rods that were in the engine when it was pulled down. (the car was bought not running and nothing was known about the engine) and found all the push rods to have about .003-.005 run out. I thought maybe at some time this engine had a different cam/valve spring set up in it and maybe had some coil bind and bent the push rods. So I ordered a new set from SBI thinking I would get straight ones. When I start checking them I see that none of them are perfect, and can get as much as .010 of run out. I called the SBI tech line and asked about run out and how much spring pressure they would accept, they had no clue.

So will a stock push rod take this spring pressure and how much run out is acceptable on a push rod for this build????


Thanks!
Dan

i would run a 3/8 pushrod. .080 wall. i got mine from trend $$$, but straight as an arrow. manton & smithbros are the best too.

The guy don't want to spend big $$. He just wants to get a push rod that will do the job. This is in a street engine.

Dan

How long are they. If they are 9 1/4 cup ball they are always for sale. Should be able to get a used 3/8 set pretty cheap.

It has adjustable rockers with the ball and ball rod. Length is 9.315

Dan

I wouldn't be trusting any stock push rod in a hp build. They sound like stock pushrods for hydraulic cams and he installed a roller rocker set up. He should go to 3/8 as said. If he doesn't want to spend the money, then how does he expect to run any type of power for any length of time? He may aswell expect to purchase a tripe a card now, since he is not wanting to do nothing but bling on it anyways.

FWIW--Last year I was installing new pushrods in my motor, tested a couple different sets for straightness in my lathe--all had some runout, some as much as .010. I finally used the cut-to-length kit from Mopar Perf, they checked out about the same as others tested.

With that kinda spring pressure over the nose,you need a real good p/r and a lifter that will stand up to it.Doesn't sound like no street car

If 200 or so for a good set of pushrods is a deal breaker , then he should sell his car and take up knitting or chess.
Nothing wrong with either of those pursuits I suppose , and they are a lot cheaper for both the initial hit and long term outlay.