What are the best aluminum cnc ported heads out there? Heard alot about AFR's and Dart's. looking for your guys opinion. Going to be going on a 502 and possibly a future 540 build.

I really like the AFR's . I think you're going to find that the difference between the 502ci and 540ci will require two different sets of heads to be efficient . Without knowing exactly what you have in mind the 502ci will like the oval port for flow velocity and the 540ci will no doubt like the AFR 315's . Tell these guys more of what you have in mind and you will be pointed in the right direction .

+1 on what my brother said above. I run the large oval port full cnc ported AFRs on a pair of 540s fwiw.

1 head for both motors?

AFR 315's. Hard anodized.

What's the next question ?

Yes don't limit the 502 with oval ports. Run the 315's and enjoy. I dyno'd a 548 with afr 305's and made 630, heads still weren't at there limit.

Working with Bob M we decided to run AFR 305's with my 502.

It's not all about the volume, it's the velocity. My 540s made 680 with full cnc ported oval port AFRs, 4150 flange Victor Jr with a Reher Morrison adapter below a 4500 flange Dominator, again, for the velocity. That was at 5500. I don't feel like they were limited by the oval port heads.

290/305/315 (as fas as size )on 502-540's is almost like splitting hairs.

Torque at planing speeds and below is useless for 99%+ of boats.

When you have heads as good as the AFR's there will not be a huge difference.

Pick which you want and be happy. Because you will be.

My IMHO would be the 315's.

I guess it all depends if you are shooting for peak volumetric efficiency on the 502ci or willing to compromise a bit till you build the 540ci . We are speaking in generalities not knowing the rest of the engine formula . As far as best aluminum bbc heads I think you can see we clearly all agree on the AFR's .

Really need to know how many rpm you want to spin and how much valve lift you want to go with. More rpm= more power& more money. More valve lift= more power and more money. Without knowing how many rpm you want to spin the motor it's kind of a waist to suggest a cylinder head.