Not much response on the race forum so I'll try here. I'm putting my 440 street motor together and would like some input on push rod size. The valvetrain is all CompCams with their hyd roller lifters, 1.5 SS magnum rockers and their extreme energy hyd roller cam. Cam specs are: lift .538int/.534ex, dur @ .050 .224int/.230ex . The spring specs are: 145 lbs at 1.875 on seat and 375 lbs at 1.335 max lift open. The push rods will be 8.350" long. I checked with a tech at CompCams and he said at those spring pressures and rod length a .080 wall 5/16" dia would be fine. It will be strictly a street motor with a max rpm (if ever) of 6,000 rpm. Thanks

That will be fine!

One drawback to bigger pushrods is they will end up rubbing on the heads someplace.

The roller lifters have holes for pushrod oiling and most of the available pushrods are also drilled. The comp rockers also have a provision for oiling the top of the pushrod where it contacts the rocker adj screw. Is this going to put too much oil on top of the head?

Thanks for the input so far. Does anyone have an opinion on the oiling issue (ie too much?).

A pushrod is a "slender column" in axial loading. This is a strength of materials issue, third-year engineering stuff. If you could get a 3/8 or even a 7/16 pushrod it could have a thinner wall and still be much stiffer. The stiffness of this slender column is what opens your valves. Stiffness increases as something like the CUBE of the diameter, so a larger diameter will really pay off.

Big block chevies used 3/8" pushrods stock and as early as the late '60s they were using 7/16 rods for high performance valvetrains with high lifts and big springs. They have pushrods shorter than RBs.

If you want to find out what Comp Cams really thinks about pushrods, check out their tech articles on valve float and bounce.

Greetings from beautiful Page, Arizona where the sun necver stops shining! Anyone in the area? I an in the light green '64Dodge D100 that still needs valve stem seals and is still losing out to the rust monster.

R.