HP difference between flat tappet and roller lifters
 

You guys think there would be any horse power difference between flat tappet and roller lifters? I know you'd have to change cams, but assuming you had a cam that was the same lift and duration? I'm running a set of flat tappet hydraulic lifters in my 306 because it's a '76 block (non roller) Just wondering what you guys think. Also, what's the best set of roller rocker arms that mount on the stock heads without modification to the head?

I don't know about just lifters but I was told by several tech's at Comp Cams that I could of expected a 5-10% increase in HP by going full roller in my '69 block. Good luck!

Speaking of, I was just looking at the Rhoads variable lifters.

Anyone run these or know anyone who does?

See tech here

Curious...

Roller lifters allow a more aggressive profiles, faster ramp speeds so the valve gets to maximum lift sooner, within the same specs as a flat tappet cam. Rhodes lifter "bleed off" some of your cam at low rpms, for example: if you had a real aggressive cam, with lots of overlap and poor bottom end performance, rhoades lifters will make the motor think its a smaller cam at lower rpms and give back some torque in the process, by not pumping up until a certain rpm and "digesting" that overlap, thus reducing bleed off of having the exhaust and intake valves open at the same time as long and there by giving you more cylinder pressure for better throttle response and bottom end torque . and then give you back your more aggresive profiles on the top end when they do pump up. they are usually a little noisy. But your only talking about a minimal amount of impact rhoades lifters can have on a cam.

Interesting info.

Thanks for the reply!