Being able to run 87 is always a bonus.

Pro 1 320s have a good exh port.

585 is respectable. What RPM?

Here's the cam I'm looking at.

The Brodix heads are on my 489 that's currently in my 272. I have Dart pro 1s that are fully ported going on that next couple weeks.

The drive is a early version Bravo 1

As for this boat, cruising rpm will likely be around 3800-4200 rpm with the intention of going fast whenever the want is there.

They are 345's with manipulated runners (at Dart foundry) and ported to ~320cc.
5800RPM

Mine that I have are 310, 320 after the porting

My cams specs...

Eric Weingartner has a video on the Brodix 312s.


They would benefit from a very mild cleanup even in just the chamber lip off the seats.

That's a healthy cruise rpm 3800-4200. Less of an issue for the larger ports.

The cam looks to be in the ball park @223° int.

The GM forged Mag marine engines would peak at 5200rpm with 224° single pattern flat tappets with 0.510 lift. Longer exh duration would keep the hp up a bit after the peak.

I've watched his videos and got the same info from him and cleaned up the chambers prior to putting them on my 489. If I remember correctly I believe he said that they were an identical head to the 088 casting with improved exhaust ports.

That should be an interesting swap. I would love to hear if it actually is an improvement. Are you changing anything other than the heads ?

I have a PP hurricane single plane intake, but I really want try it with the rpm air gap first. But here are the flow numbers done on a 4.300" bore. Thinking of adding 1.8 rockers to get my valve lift to .599" instead of .566 with the 1.7s.

Depending on how much time and energy you have I would leave it all alone other than the heads. Then you will know if they really did anything. If you change 5 things you never really know what helped and what didnt What kind of power do you think it is making now ?