Ok. Been talking about this build forever, every time I get close to a start something else comes up in my life and this hits the back burner.
I think I'm ready to start slowly accumulating parts.

Want to build 540ci, na, pump gas 93 (I live in Australia and from what I understand your 93 is our 98. Correct if I'm wrong), hydraulic roller setup, 650-700hp max (want to use bravo Xr. It's a light 21' boat), efi and closed cooled, maximum reliability, no intention of forced induction.

Here is what I know I'm going to use so far (chime in if anyone has a reason why not to use the following):
- Dart big m sportsman 4.5 bore, 9.8 deck
- scat crank 4.25
- scat rods
- sr pistons
- dart pro 1 marine heads
- Holley efi and intake
- Dana exhaust manifolds

Here's the questions so far:
- What comp ratio should I be going for and what cc heads and piston shape to suit?
- cnc or standard marine heads?
- cam?
- rings? Brand, file fit or standard
- sump?
- dart offer block prep before shipping, is this worth while or will it need to have machine work done anyway?
- anyone used holleys self tune on boat? Is it reliable or would it be better off dyno tuned?
- valves and roller assembly (lifters, rockers, push rods etc.)?
- closed cooling kit?
- bearings?
- where does everyone get there billet pulleys?
- ignition?

I'm sure ill think of more later
Thanks for any input.

If I was going to start from scrach I would go with a tall deck block. 10.200 More room to expand later.

Haxbey speed has done a thread on the Holley Efi a lot of good info.

Start at 4.560 bore. Still plenty of room for a few overbores after that. 10.0 to 1 compression. 10cc small dome pistons.
AFR 315 cnc heads and a decent size hyd. roller will make 700 and still have good dock manners.

I have heard mixed things on afr's casting thickness. I know everyone says they flow great numbers from the box however I'd like this build to last a long time and darts pro1 heads look the better option in that respect. Not knocking afr, I really do think they are at the top of the tree with dart and brodix, just like some meat.

Want to stick with the 9.8 deck height due to height restrictions in the boat. It's going to be a tight fit under the hatch as it is, every inch will count. No intention of going bigger once built anyway, I'd rather build a whole new motor if that was the case. It's a ski race boat also and we have a 572ci capacity limit.

Where have you heard this about thin castings on the AFR's . I think someone is feeding you

Sounds like a good build Kurt. I'd look into the Callies Compstar stuff as well. Really good quality for the $. You can easily hit your hp goal with the Dart's or AFR.

I did a very similar 540 combo in the spring for a whitewater Jet boat. It was lower compression so it would live on 87-89 octane, and had a very mild hyd roller from Bob Madara to ensure the valve train has a long life, Gen VI block. This combo could easily hit the 700hp mark with a couple minor changes.

540, AFR 305's, Holley HP EFI, Dana exhaust. Dyno'd fully dressed with wet exhaust.

I just read a lot of forums through google searching on heads and that seemed to be the common complaint about afr? But then again it's not fact just opinion. I'd be happy to use afr, dart or whatever gives me the most reliability. Any reason not to use dart heads?

Nice motor, exactly what I'm thinking of, reliability and longtivety is key to me. My wife hates me working on the boat so I want to do it once and do it right. I'm not rich by any means but I'd rather take a little longer and spend a little extra if need be to do it right. I'd be happy with the dyno numbers your making with that motor. It's going in front of a bravo Xr so I figure 700hp was my max (bearing in mind light 21' boat).
What is that closed cooling system your using?