3.0 for 4.3 swap?

[drun_trucker]

My old 86' SeaRay has a pretty good running 3.0L but I think I'd like a bit more umph to get her going? Ask some questions and reading a bunch on boats of that era tell me they are heavy and the 3.0L might make it an under powered boat. I really LOVE the boat it's very very clean for her age and I don't want to get rid of her. I really do want to get more punch out of the hole and top end.

I want to know if pulling out the 3.0L to put in a 4.3L or bigger would be worth the effort? I know that I have to get a matching out drive for the engine replacement, but that is fine. The gimbal housing can all stay as long as I go mercruiser swap...

Horror stories or success stories and recommendations please please please.

 

[bigbob_FTW]

I would love to have your 3.0 to replace my 2.5.

 

[drun_trucker]

Tell you what...if I can find a motor/out drive I will sell it to you. 2.5, is that a merc?

 

[drun_trucker]

Sorry I didn't see your bio...

 

[drun_trucker]

Looks like maybe I should just try to sell the boat and get a bigger one...

 

[Rick Stephens]

I'm swapping in a 4.3 into my 1990 boat right now. Still working up all the parts, I bought a boat that the floor and stringers had been completely rotted out. The prev owner had stuck a brand new Vortec 4.3L in it. Then ripped the floor and stringers out and gave up on it. So I got a new motor and an Alpha1 GenII for next to nothing. In my case I am going to swap the outdrive, transom and everything so I go from original Alpha 1 to the GenII and get power steering along with it..

If I just wanted to drop a 4.3 in a boat with an 3.0L Alpha1 with its 1.98:1 gearing, I'd just do it if I didn't find a motor with a leg with it geared to 1.84. No big deal. Have to prop the hell up, maybe go to a 21 or even more. But it would work. Hardest part is all the other stuff like exhaust, Y pipe and so on. Thousands of dollars to buy piece at a time. Best way to get that is buy a rotted boat like I did and pull everything.

Have fun! Nice part with starting with your own boat is you know what you have.

Ric

 

[achris]

I swapped a inline 6 (165hp) to a 4.3... The difference was night and day. I can only imagine what the difference would be going from a 3 litre to a 4.3.... WOW!!!! Just do it!!!!!!

Chris......

 

[Bondo]

Ayuh,..... I went from a '74 3.0l to a '94 4.3l LX 17 years ago, 'n haven't looked back,......

 

[thumpar]

Personally I would sell the boat and get one with a 4.3l in it if that is what you want. The difference in price from a 3.0l boat and a 4.3l boat is usually only a couple hundred if anything. That swap is a lot of work and money.

 

[PeterB26]

A lot of Bertram 25's (and 26's) were built with twin inline 6's. When it came time to scrap the old iron the debates were rampant over going to the 3.0L 4cyl or up to the 4.3L v6. A couple of guys went 4.3L v6 and were very unhappy because the weight made the stern ride too low. Meanwhile the 3.0L swaps didn't give up any top end from the straight 6's performance because they were lighter and rode higher.

On the other hand the 4.3L upgrade in a Bertram 20 like Acris has (many of which were also originaly fitted with inline 6's,) is a gem. A 3.0L in that boat would be just underpowered.

My point is is the best choice may be very hull specific. Two Bertrams about the same vintage, similar hull forms, BUT two different "best" answers to your question! Find someone else who has tried the upgrade in your particular hull and see how it worked for them before you jump right in. If you can't then think long and hard about the weight and how it will make your boat sit/ride/perform. Maybe even do a litle test by putting some ballast back there to simulate the greater weight aft and see what happens. Bigger isn't always better.

 

[TCATTC]

I'm in the middle of a 3.0-4.3 swap right now. The cost is not that significant (in boat terms $$$) over fixing a cracked 3.0. With aluminum intake and exhaust manifolds, and an aluminum water pump, the weight shouldn't be much more than the old 3.0. I personally think you are making a smart move.

 

[Bondo]

A lot of Bertram 25's (and 26's) were built with twin inline 6's. When it came time to scrap the old iron the debates were rampant over going to the 3.0L 4cyl or up to the 4.3L v6.

Ayuh,.... I've now got one of those in the stable, a super clean '78, most all original with the I-6's, 'n MC-1 drives, both right handed,.....

Boss's Bud, bought an exact copy, picnic cuddy's,...

Boss's Bro bought a sister vessel with twin Outboards,...
Mark took the Mercury motors off, 'n dropped on twin big block Hondas,...
Super Fast, will Smoke either of her sisters, like they're goin' in reverse,....

These twins look Wide, but I know crank shaft centerlines many times won't allow V-motors, without fillin', 'n recuttin' the hull,....

 

[achris]

Ayuh,.... I've now got one of those in the stable, a super clean '78, most all original with the I-6's, 'n MC-1 drives, both right handed,.....

Boss's Bud, bought an exact copy, picnic cuddy's,...

Boss's Bro bought a sister vessel with twin Outboards,...
Mark took the Mercury motors off, 'n dropped on twin big block Hondas,...
Super Fast, will Smoke either of her sisters, like they're goin' in reverse,....

These twins look Wide, but I know crank shaft centerlines many times won't allow V-motors, without fillin', 'n recuttin' the hull,....

That's particularly true with the Bertram 25s. They weren't wide enough in the rear to accommodate the twin V6s that replaced the in-lines, so Bertram built the 26, which IS wide enough in the rear to take the side-by-side V6s.... (or V8s if you're really keen )

Chris........