1988 3.0 Mercruiser 140 hp questions

fdheld34 · #1 01-30-2010, 12:26 PM

I am trying to figure out if a 1988 3.0 Mercruiser 140 hp motor will mate with a mercruiser pre alpha series outdrive. I have an opportunity to purchase the motor and want to make sure it will in fact mate up with the pre alpha. The person I am purchasing the motor from says of course..but looking for more opinions. It will be going into a boat that currently has an older 3.0 in it already.
Any help appreciated....Tim???...anyone

Bushwacker · #2 01-30-2010, 01:48 PM

Fred, while you're at it, why not also ask if any of the later model V-6 engines will work with that outdrive? I believe Nothinfancy is going to marine mechanic school, so he might know or be able to find out for you. Denny

oldfielder · #3 01-30-2010, 02:40 PM

go over to boatered forums-you'll get your answer in a jiffy

fdheld34 · #4 01-30-2010, 06:12 PM

Denny....so you think something like a 4.3 would be better..I am on a budget as usual!!! I do not want to have to change out my outdrive or mess with motor mounts etc!!!!
Oldfielder...I will post question on other site (great info over there) I did not know it even existed

oldfielder · #5 01-30-2010, 07:40 PM

I've gotten a lot of advice there-there are some serious experts on that forum

workinpr0gress · #6 01-30-2010, 08:48 PM

just grab an old scarab or chapparall, four wins,etc beat up a little you can always find used up hulls from the gas happy "boat drivers"... or pick up the quintesential Bayliner prolly cheapest in the "edition" that looks like a floating pop up camper with a point that has cockpit railing like a "holiday in express" in balcony...depending on how much your willing to spend you could end up with newer technology at a huge discount. you can steal a lot of good parts off it to to resell then giddyup to the dump with the hull or make a planter out of it if your really feeling frisky....lol

fdheld34 · #7 01-30-2010, 08:54 PM

BruceB..good idea on donor boat...never thought to go that route...guess i will used jaxed and look for bayliner etc.
Still waiting on email to get access to boatered...wanted to keep the boat as close to original setup as possible though.

workinpr0gress · #8 01-30-2010, 08:57 PM

350 mpi.......in some of those turds

Bushwacker · #9 01-31-2010, 12:03 AM

Quote:

.. so you think something like a 4.3 would be better..I am on a budget as usual!!! I do not want to have to change out my outdrive or mess with motor mounts etc!!!!

Fred, I recognize that a near-stock original setup is probably the cheapest, but as a mechanical engineer I'm just partial to smooth running machinery! A large displacement I-4 w/o balance shafts will buzz quite a bit but you might not care about that, provided it's reliable. Just thought that while you're looking around, it might pay to think out of the box in case you find a deal on a more modern set-up. It's probably not that hard to find a bayliner full of rotted plywood with a fairly low time engine/outdrive, so finding a donor boat could be a viable option if you have the time and like turning wrenches! I think Skip has found that replacement parts for some of the really old outdrives can be pretty expensive. A V-8 would be way too much weight unless you wanted to spend a lot of $ for aluminum heads and fresh water cooling! The 4.3L V-6 isn't naturally balanced either, but it's a little smoother than the big I-4, similar weight and more power. There was a Seafari on here some time ago with that setup and it looked like a neat installation.

There's a reason they did 3 valve jobs on that old engine as described in that original ad you sent me: it was underpowered with that 120 hp engine! Sounded like they did a lot of diving, and if they loaded that boat up with 4 divers, tanks and gear, and ran it w/o a vacuum gage, they probably ran it well under 5" vacuum, which will burn valves pretty quick. That boat is not underpowered with a 140 if you don't overload it . . . 2 different 140 I/O Seafari's have made the 170 mile trip to Green Turtle in the Abaco's with me, and they would run about 23-25 mph at 7" vacuum. They weren't heavily loaded however, and because they're 5 mpg rigs, they didn't have to carry nearly as much gas as I did with my old 115 V-4. They burned about 45 gallons to my 65 gallons!

Denny

Blue197320 · #10 01-31-2010, 12:29 AM

im not an I/O guy, but i will tell you that a 4.3L chevy motor is pretty durable. i had one in my s-10 and sprayed nitrous thru it. at least 6 10 pound bottle probably more and one time it hit the speed limiter of 98 mph and the pcm shuts off the fuel but it kepy spraying. didnt die after that. no problems with that motor.