A member on the NCRS forum posted this information regarding
the use of the rectangular port intake with oval port heads.
I thought I should share it with the group here. My thanks
to Michael Hanson for this information:
"Steve,
The stories about rect port intakes used with oval port heads are true. The combination actually does fit without leaking and it actually does make gobs of low/mid range torque. The power falls off fast at around 5000-5500 but pretty incredible at 2000-5000. It's all about port velocity at lower engine speeds. Everyone knows that the big head ports kill low/mid torque but the mismatch with small head ports and large intake ports kills higher RPM horsepower. Somewhere between is a nice balance that keeps port air velocity high. The fact that even the oval ports are large helps to off set the problem of the mismatch. There are more reasons but way too deep to cover here. Has to do with the wave bounce and speed.
In the 60's, a friend bought a new L88 short block for his 57 Chevy race car. He couldn't afford the new big port Aluminum heads for quite a while so he installed a set of oval port heads on the engine and went racing. Amazingly, the car ran times in the same range as all of the other guys that had the same L88 block assy, but with the proper big port heads. When he finally purchased the new aluminum heads, he was surprised to leard that the car ran times that were almost identical to his original times with the small ports.
In the late 60's, I was able to "make a few adjustments with the GM warranty paperwork" and help a few buddies with new 68-69 Camaros get an L88 short block under warranty to replace their 396 short block. One car was an original 375 HP with the big port heads and another was originally a 325 HP with oval port heads. For reasons I don't remember, the oval port heads were reinstalled on the 325 HP car with a new rect port 375 HP intake and L88 short block. All else was the same from car to car, right down to the header mfg and diff gearing. Both cars ran nearly identical times with the headers open but the car with the weird combo oval port heads was slightly faster on the street. "
Steve