[Randy Allen]

I have a Butler built 468 with 6X-4 heads ported to 256 cfm with a 238/244@.050 cam with Rhodes lifters that’s never been started because of a Pro-Touring build for a ‘77 Can Am. A buddy is building an 535 MR1 with high-ports and has some original round-port 72cc E-heads. My compression is roughly 10:5 and the horsepower simulation has it in the 495-505 range. Is it possible to open the chambers up on the 72cc E-heads to 87cc or more to reduce effective compression and then port the heads to flow 290-300 to get another ~50 horsepower?

If not, what round-port would you suggest and flowed to what cfm? I have no intention of going to a bigger cam as its a street car where a good idle and wide torque curve is important. I may occasionally road race or open road race (to 168 mph). It’s a 3.73 rear gear with a T-56 that will weight about 3750 when complete.

Thanks for your assistance.