3.0 or 4.3 mercruiser ?

[Tarpun]

I,ve been thinking about replacing my 1972 Seafari's original 3.0 pre-alpha engine and drive with a more current model. I have come across complete later model 4.3 with Alpha 2 drive. It's a more current 4.3 with balancer. My original plan was to stick with the 3.0 for good economy but since the avail. V6 has me thinking. I know it weighs more and will burn more fuel but it will be less stressed and allow a faster cruise. I was always under the impression the 3.0 was a good unit but a couple folks have said they have gasket and manifold problems and that 4.3 is better in that way, also that the 3.0 is too little power for the Seafari. I don't plan on taking divers and gear or generally using it with more than 2 or persons total. So how about some learned opinions from the forum. I would love to hear off hands on experience. I did a site search and did get a little info. How about it ? Thanks in advance. Dave

[gofastsandman]

Hey Dave,

My 4.3 in my `03 weenie mobile truck lost the intake gasket @ 59K. It was a known problem by GM and Texaco and their wonderful Dex Cool. I got a gasket set made by Fel Pro badged as the "problem solver". I had a tech tell me that he had seen freeze plugs fail because of Dex Cool. Little trucks and small scraped knuckles. How do big folks work on these?

The 4.3 is a good motor. A 350 minus 2 cyls. I`ve seen them turn 250k easily. The 3.0 is also seen on the road from the `90s. Tough call. My `03 is rated @ 240 ft lbs.

Cheers,
Sandy

[db3155]

3.0 Mercruiser is a commercial engine its never been in a car.

[gofastsandman]

Originally Posted by db3155

3.0 Mercruiser is a commercial engine its never been in a car.

Of course a Mercruiser has never been in a car.... Maybe from Cuba? `59 Poncho? 53 Chev truck?

The thing is we marinizzze motahs. Get it?

It`s....it is........ its.....a pronoun.

Many 3.0`s are in my neighbor`s driveways...........

Ogden Nash where are you now?
GFS

[Blue_Heron]

The 4.3 V6 will require different motor mounts than the 3.0, so the boat will need some modification to make it work. Just something to think about.

The current 3.0s are 140hp, the 4.3 MPI is 220hp. The 3.0 should be plenty for a 20, but a 4.3 will really make her scoot if that's what you want.

Dave

[Entourage]

4.3 is a great motor. Look the Chevy astrovan and safari vans with the vortec they are great. I have twin 4.3mpi in my 29 footer with bravo 1s and wot is 33 knots.

[Tarpun]

I'm quite famililar with the 4.3 , put alot of miles on one. Sandy, I had the same anti freeze issues with a couple of vehichles. bad product. I think the 4.3 is a very durable well made engine. (after all it's 3/4's of a small block Chev) Very reliable but never impressed me with it's fuel economy in a vehicle. I was wondering if it would be any better in a boat. Anybody have one in 20 Seacraft? What is your fuel burn?. I'm happy with 3.0 but lately I've heard a bunch of negatives about corrosion problems, manifold leakage. lack of durabilty pushing a 20' boat. I'd always heard good things.Just got me thinkin'. A good deal on a clean package adds to the thought process.
Entourage, whats your cruise and fuel burn at cruise?

[Entourage]

I cruise at 24 kts at 3800 rpms wot 4700 rpm 33 kts and do a 60 mile round trip with a charter of six with fish and burn about 30-35 gallons of fuel. Using mercury inertia 15 pitch stainless props. My friend has a older carburated 4.3 with the 4bbl carb and his fuel consumption isn't as good especially when he gets on it. I have a 20 ft safari and I was going to put a 4.3 in it just never did it. I know the engine compartment may be tight cause I did do some measuring.