I am switching from sbc to BBC in my 22 sport cat. I picked up an old jet boat that has a Mark IV 454 that had recently been rebuilt .030 I have pulled the pan and it was rebuilt very well with some very good parts.
My question is:
This motor has Casting number 14081045 Oval port heads that have had some minor port work done to them. Should I consider getting some rect port heads? Or will these work well. Not planning on spinning the motor over 6K.
I also have not had very good luck finding a oval port 6-71 intake manifold? Who would you suggest trying if these heads can stay with the motor?
Thanks -------- Tee

Tee!
I have done several 454 oval port installations. Your heads are OK, but not great. Merlin iron oval port heads on this combo will outrun almost any other head, period. For intakes, B&M used to make one and I don't know if the new owners, Holley, still make them or not. I have often used the rectangular port intake on the oval heads. This works pretty good, though it is not ideal. From my experiencej, though, it will beat the rectangular port head on this engine. You do need to pocket port the head. Post or pm if you want more details

For maximum performance with any blown engine you should use the largest ports possible. Small "high velocity" oval port heads will work the best with a naturally aspirated engine but not a blown engine. Install the rectangle port heads.
Dennis Moore

I would very much like to see a back to back test of oval versus big ports on a 454. I will work on that. I have seen several guys with Merlin ovals succumb to the "bigger is better"idea and slow down. Also, if bigger is better, then we all need Pontiac Pro Stock heads

I would use rectangles. On a 454 the 325 chevy heads are the best choice, in my opinion. However, I definatly would not go over a 345 intake runner. Quite frankly, I think they're a little big for a 454, but they'll work.

DAVE