4.3 Power upgrade

[MRJ82]

I have a 1989 19' chris craft cuddy with a blown head gasket. Since I am going to be taking the motor out to freshen it up anyways, I am wondering what your fellow boaters advice would be on upgrading the power out of this motor. And lets be realistic here, I don't want to spend $3000.00 or swap it out for a 350. Can anyone out there shoot me some ideas?

 

[mylesm260]

Re: 4.3 Power upgrade

Get a running, low mileage 4.3 vortec out of a 1996 or new chevy 4x4 truck or AWD van, and then marineize it.

you can keep 90% of you're parts, and you could stand to gain 40-75 HP over what you've got.

 

[MRJ82]

Re: 4.3 Power upgrade

That wouldn't be bad to start with. Would there be anything I can do to vortec motor to get a few more ponies out of that?

 

[mylesm260]

Re: 4.3 Power upgrade

http://forums.iboats.com/showthread.php?t=335053


Cam + valve train work to make the cam work.

There is a lot of debate as to weather or not the added performance is worth the increased risk of water ingestion.

A 200 HP (AWD or 4x4) truck 4.3 is good for about 220-230 HP in a boat, if setup properly.

If you change the cam as well, you can tack on another 20 HP or so.

The performance cam is just slightly better than the stock vortec cam. Any "hotter" than that, and it will cause ingestion for sure.

 

[MRJ82]

Re: 4.3 Power upgrade

I have some 10 to one flat top pistons left over from a 350 project. would I net any gains with them, and what cam would I run then. And how does the cam effect taking in water? I also have a 650 double pumper carb, would that be to much for it?

 

[danond]

Re: 4.3 Power upgrade

MRJ82 - it'd probably be better for you to find a boat with a bigger motor if you want big gains. That's typically the best bang for buck. Unless you're a marine mechanic guy or want to mess around with water ingestion, rebuild the 4.3 you have a throw on a 4bbl carb. You'll be impressed with the HP gains.

I went from a 2bbl to a 4bbl on my 4.3. It was noticeable. You also absolutely MUST use a marine carburetor. At best you'll get nailed by the coast guard, at worst you risk blowing yourself up using an auto carb on a boat.