pontiac 400 in ski boat?

[jdmerk]

i have a 72 Lemans with a 400 in ir currently, has maybe 325-350hp. and my dad recently gave me his ski boat its an 88 four winns bow rider with a Mercruiser 120 inboard/outboard unit, this is a GM(i believe) 4 cylinder with a 120hp rating. the boat is kinda heavy and does not like to plane out when im pulling a skiier. also im planning on eventually swapping out the 400 in the pontiac for a 455. which leads to the obvious question...am i retarded for wanting to put a pontiac v8 this boat? i mean i have been looking through the very slim knowledgebase on the internet that i can find about swapping marine engines with auto engines and marinizing them. but i just dont know if this 120 transom could support the torque of the 400, and what other associated parts would cause me problems. will this engine even bolt to the transom? can a bellhousing adapter be used to make it work? what do i do with the exhaust? do i really need the marinized starter/carb/alternator/fuel pump etc? im not even sure if this is the right place to ask but its the best i can think of, thanks in advance for your help guys

[Pontiacmuscle]

You'll see bellhousing and manifold kits on Ebay to put a Pontiac in a boat.One just sold on Evilbay......455 2-4s etc.....nice. Kinda cool even though its an Olds motor.Id put an ad here and on CP if your looking...they're out there.

http://cgi.ebay.com/ebaymotors/Tahiti-Jet-Boat-Modified-455-Pontiac-Engine-Fast-Fun_W0QQitemZ4635610128QQcategoryZ80653QQssPageNam eZWDVWQQrdZ1QQcmdZViewItem

[jdmerk]

thanks for the info, i see yours is a jetboat though, am i going to have any problems running the 400's power through this 120 transom, its it gonna blow pretty quick or can it take the heat. i was also thinking about running straight headers like yours but i dont know if i could stand the noise like that one the water.

[jdmerk]

NM i was thinking that was your personal boat

[george kujanski]

A '88 boat with a 4 banger is most likely a Mercruiser engine. B4 that boats with a 4 were GM engines based on a Chevy 6 design, at least mine was.

A 4 just does not have enuf low end torque for real skiing, mine didn't.

The electrical pieces need to be marinized, i.e. to minimize things sparking in the engine bay, but most of those pieces will transplant.

Boats were rated for max allowable horsepower so your hull may not be rated for the 400.

If you go for it, you will also need water-cooled exhaust manifolds, the exhaust normally goes out thru the stern drive after being cooled by the water dumped into them.

Boats with Pontiacs that I've seen aren't coupled to a stern drive.

If your boat has a 4 it was probably also available with a V6, the GM 4.3L was popular in those years, my brother's boat has 2 4.3L engines. Perhaps you can find a bad hull with the V6 which would be easier to transplant.

Try lowering the pitch on the prop for a short term fix also.

George

[jdmerk]

going the other way... http://www.angelfire.com/il/xd/cars.html

[Pontiacmuscle]

JD....If I had it; it would get a Pontiac post haste after I found the partz of course. One with a built Pontiac has to rock n roll!

[Steve Barcak]

I have 2 boats with Pontiac power. 1 is a jet and the other is a v drive/prop. I don't know of anyone who has put one in front of an outdrive. Pontiac marine wet manifolds are available new or used and would be the way to go if you cannot use or don't want headers. I use regular alternators on my boats but, I also do not use an engine cover. With an engine cover a marine alt is a good idea. I also use regular heavy duty staters. I would suggest building or buying a larger oil pan as you should have room and use a good size oil cooler too and have an oil temp gauge. Oil temp goes nuts in a jet boat and is something you want to keep an eye on.
good luck.
I do have Pontiac powered boats on a separate page of my web site if interested.

Steve Barcak www.pontiacheaven.org

[jdmerk]

what would be the most difficult part of this swap? as i see it i can resolve the exhaust problem with headers if i absolutely must, for the mounting i can fab something up myself, throttle, fuel, and electronics wont be that hard, i was planning on a raw water/ethelene glycol cooling system, but i dont know what to do with the drive unit...should i scrap the mercruiser and go with something else? is it worth working with?

[george kujanski]

Another thought....the drive is probably not rated for more horsepower either. The high horse units are bigger, bigger gears, etc.

I think you are screwed using the existing drive.

example: mine is a Gm 305 cu.in., 200Hp rated, uses a Merc. Alpha I drive. A friend's boat has a GM 7L., (454 I think) uses a Bravo I drive, physically bigger.

George

[rwfisher]

Here is a couple shots of the 16' with the same outdrive. No problem handling 400HP. Nicson made the front mount/water pump, rear flywheel cover/mount and the water cooled exhaust manifolds. Olds/Pontiac used to be pretty popular in these boats. Try this page out: www.jetboatperformance.com

[jdmerk]

have any shots of the bellhousing area?

[rwfisher]

Send me an Email and I can get some shots to you. File size to big for posting here. [email protected]