!40 Mercruiser and I/O

[brushhippie]

I have seen and heard folks talk about how efficient the 140 is...anybody still running one of these?...What can I expect and what prop on the 20' Seafari is the best for speed and fuel consumption...AND how much weight can you add without changing it?...I fully intend for a while to run the 140....I may at some point convert it to diesel but for now I want to try and dial this one in...just lookin for ballpark where to starts! Thanks

[Terry England]

Brush, I had one in a 20' Safari, just like your's. Conner and I crashed around in it in the 70's
It isn't the Chevy Nova motor. The 120 was. This is a special block Chevrolet cast for Mercury down in sunny Mexico, before they were NAFTA partners. it uses 327 4" pistons and does not develop enough torque to destroy a type 1 Alpha drive, but they have the typical gimbal bearing and bellows issues. The tilt and trim work great. The cylinder wall thickness is very thin and so there is a problem if you bore them with the cylinders cracking vertically and the engine filling with water. Along with the typical manifold and elbow replacement schedule of three year intervals, the cast tensioner on the alternator cracks, and you can't keep the belt tight. Other than that they are flawless and pretty good on fuel - 3+ MPG.
If I would have put a stubby bracket on it with an outboard, in 1978, like Denny, I'd probably still be running it.

[Bushwacker]

Boating Magazine did a test of the 20' Seafari in 1969 with the 140 Mercruiser and published a very good report on it with lots of detail on the construction, laminate schedule, etc., including a complete performance report.
http://www.classicseacraft.com/broch...cle/index.html I think this is a jpg file so it's pretty hard to read, but I have a good .pdf file of the original article that's much more readable. I have your email address, so I'll send that to you. I also have a couple of the factory brochures from '69 and '72 which I can send if I haven't sent them already. In that test, they ran a 15x21 prop; it was a 5 mpg rig, which will pretty much match a modern 4-stroke outboard!

[brushhippie]

Thanks for the info guys...Ive got the kit comin to fix the bellows and shift tube, should be fun...hopfully I can get her in the water fer a bit before it gets too cold...Momma wants to go cruise Table Rock lake while the leaves are turning...I better get busy! Already got my eyes open for a diesel replacement.....shouldnt be too hard to find one thatll make 140 hp! one that doesnt weigh ten thousand pounds may be a trick.

[DonV]

Originally Posted by brushhippie

Thanks for the info guys...Ive got the kit comin to fix the bellows and shift tube, should be fun...hopfully I can get her in the water fer a bit before it gets too cold...Momma wants to go cruise Table Rock lake while the leaves are turning...I better get busy! Already got my eyes open for a diesel replacement.....shouldnt be too hard to find one thatll make 140 hp! one that doesnt weigh ten thousand pounds may be a trick.

You forgot to add......and doesn't cost an arm and a leg!!!!

[McGillicuddy]

Find an old bt4 from a bread delivery van. $2-3 grand. 750 lbs of econo-muscle. Marinize, supe-up a little, and presto, a 150 hp, 265 ft/lbs of torque tank. Get a big as prop and occasionally visit a fuel pump

[FLexpat]

Originally Posted by McGillicuddy

Find an old bt4 from a bread delivery van. $2-3 grand. 750 lbs of econo-muscle. Marinize, supe-up a little, and presto, a 150 hp, 265 ft/lbs of torque tank. Get a big as prop and occasionally visit a fuel pump

https://www.youtube.com/watch?v=vMRddBOD4fg

[McGillicuddy]

yeah, they are a lot bigger and heavier than a 140...
but boy that does sound sweet

[brushhippie]

That would be awesome but much too heavy...I fear I wont find a diesel light enough....heck the guy swears there is 100 in all cylinders...that oughtta be good for awhile...Im more of a slow cruiser...stretch that dollar..I plan to rig this one to travel...weight is a huge deal really.

[Bushwacker]

If you ever had to replace the 140, the best candidate is probably the 4.3L V-6 based on the old Buick 90 degree V-6, which I believe is the 350 cu. in. V-8 with a couple of cylinders sawed off. It'll fit in the same place, is lighter than the 140 and should be about 200 hp, so boat would be a rocket with that power, although maybe a bit thirstier! Another member on here up north had one with that power and it looked like a pretty nice rig!