daveintexas

Man i appreciate all the advice. My machinist is very good at what he does but he builds mostly blown alcohol and other engines for mostly cars. He has built several marine engines as well and is hell bent on making sure i build for torque and not for horsepower which i understand, but, he is all about oval ports, dual planes, etc and from what i have seen here on the posts its about rect ports, single planes, etc. i know yall guys build alot of marine stuff so that is why i come to you to get the marine opinion. i dont want to piss off my machinist by not taking his advice. he wants me to get a large oval port head and oval port dual plane intake like the airgap style and put a 1-2"phenolic spacer on top. This motor will hopefully be going into a cat.

daveintexas

I like the price of the Canfields compared to the AFRs. I'll probably go with them. Are there any concerns with the raised exhaust ports? They state you need custom length pushrods. How much do those cost? Thanks

the duke

apples to apples, there is no comparison between Canfields and AFR's. you are talking two totally different animals here.

Pushrods cost the same no matter what length they are. "custom" just means that you have to use an adjustable length one to get the correct valve geometry set. Both crane and Comp have good articles on their web sites about checking this.

the duke

Remember who is going to be writing the BIG check to him. There is nothing wrong with the large oval ports. You can get some serious HP from them if they are ported correctly. They flow ok, put their strong point is that they have very good velocity.

Don't get too confused by all the numbers thrown around. For example, 2 sets of heads that both flow 390cfm @ .700 lift are not usually the same. The ones that do it with the smaller port are going to have better velocity, and make more HP. See my post above about Canfields and AFR's. Not saying Canfields aren't ok, because they are. But look at the runner size, and the flow. The AFR's have smaller runners and greater flow than the Canfields (and most other heads). Thats why they make HP, and thats why their price tag is what it is.