Hi everyone. I have a 98 Crownline 266 BR. More of a family boat. Currently has the junk 310hp-454 carbureted engine, 680 original hrs. Bravo 3 dual prop.
I’m looking at yanking the motor within the next few months to either go through it or swap it with something different. It has a lot of hours and it’s extremely low on power. It’s been working fine but I’m starting to hit a few issues when I go out. I want to go through it this winter and have everything fresh for next summer.
I need help deciding for a Efi swap- 496-502.
or keep a carb motor. I realize that the engine I currently have is basically 2 bolt main junk. I’m a do it yourself or so I have no problem building my own engine or possibly find a used magnum that needs a freshen up. Does anyone have any input? I definitely want some more power but I don’t want to get into the territory of destroying my bravo 3. I like to shoot for reliable a 450hp .

I mainly just need help deciding if it’s worth switching to MPI or EFI at all. Do I gain any power? Is it even worth my time or just more problems in the long run, I realize carbs are just straightforward and simple. Probably use a little more fuel but I think I’m OK with that if it’s going to keep it simple.

Thanks-Dustin

Really , really hard to beat a 502. Stay with low lift cam (say mid .500”s) and maintenance becomes easier.

Put a stock 502 EFI in and go boating

A low hour 496 might give you many trouble free hours of boating.. but 502 seems to always be the answer to this question.

The 310hp/454 engine you have is not "junk" by any means and 266 hours is nothing for it. It will go 1000+ hours. You should find out why its down on power before doing anything.

What's your budget? For about $28K you can buy a new 500EFI which would put you into the ponies range you are looking for. Used/pre-owned engines are still relatively rare; but swapping to a 502 is going to cost you at least $10K...slightly more for EFI.

Griff, I typed incorrectly. I’m sitting at 680hrs. And I would classify that 2 bolt engine as junk. Not a terribly powerful engine unless I change almost everything and add 4 bolt splayed caps

drag race guys routinely run into the 700hp range on two bolt blocks with main studs. the only time you would need splayed mains is if you are 1000 + hp or spinning it 7500 plus. I ran a set of two bolt studded blocks converted to 496 strokers that made over 500 hp with no issues till a valve retainer failure.

I agree with the above comments. I would not hesitate to use a 2 bolt block with main studs, line bore (if required), new cast iron rectangular port heads (or aluminum if you can afford it), a mild cam and new pistons and rings to make an easy and reliable 450+ HP. If you want, you can put a stroker crank / rotating assembly in it and make a 496 out of it. I good intake and marine carb would keep the cost down and be reliable. If you are set on EFI, you might be better off to buy a rebuilt 502 with EFI and it is going to cost more than $10K.

I disagree. Keep the OE engine to put back in when sell the boat and/or use for back up. Just my opinion.