273 Rocker Arm to Shaft Clearance

[RustyRatRod]

I've witnessed the ductile IRON factory rockers running 6500 plus with a .650 lift flat tappet in a small block. For several seasons without a failure.

 

[rustycowll69]

From the Jan 1963 issuer of HR magazine. Page 33 on the then new 426 Max Wedge.

" Rocker arms are cast malleable iron..."
"..have run hundreds of times at the drags & will exceed 7000 rpm without audible valve float. Chrysler designed the valvetrain to be stable at 6500 rpm & it fills this order with plenty to spare."

Hey, if you read back to the beginning of the thread, I said run 'em as is. Then multiple people said that was excessive clearance and they needed to be bushed, etc. I said it was a waste of money. If you're going to spend that much to "fix" them, you might as well buy really good, roller tip rockers.
Hey, I got no complaints about the 273 rockers, they'd be my first go-to choice of rocker for any of my SB stuff. But I don't have excess cubic bucks for frivolous(to me) expenditures paying someone $400 to "perfect" what's been good enough as is, for me. But if someone wants to spend money, go for it, you're circulating money and keeping the economy going. More power to you.

 

[Rat Bastid]

Hey, if you read back to the beginning of the thread, I said run 'em as is. Then multiple people said that was excessive clearance and they needed to be bushed, etc. I said it was a waste of money. If you're going to spend that much to "fix" them, you might as well buy really good, roller tip rockers.
Hey, I got no complaints about the 273 rockers, they'd be my first go-to choice of rocker for any of my SB stuff. But I don't have excess cubic bucks for frivolous(to me) expenditures paying someone $400 to "perfect" what's been good enough as is, for me. But if someone wants to spend money, go for it, you're circulating money and keeping the economy going. More power to you.

If I was going to run them that loose I’d do it with hydraulic lifters. Then the rocker is always against the shaft. With lash, they will be noisy. As long as the noise doesn’t bother someone then it’s ok.

I can make the argument that .003 isn’t too loose for some guys. Like the guys that think 10 psi oil pressure at idle is ok, or the guys that continue to use 20w50 oil that’s been obsolete for a correctly built engine since the mid 1990’s.

Those guys can use the clearance.