repowering my 1981 aquasport 22-2 family fishermen

[1998z28]

Hello everyone,  Im kinda new at this whole boat forum thing, bear with me lol.  & my spelling sucks so BACK OFF! lolol.  For the past 10 years iv been rebuilding my 22-2 family fishermen (money pit),  iv done it all! outdrive, gimble ring, wires, gauges the list go's on........  my question is about engine replacement!  after 35 years of use, my exhaust manifolds have sprung a leak :( and yes, its worst case scenario!  It started leaking on the INSIDE, down into the top of the exhaust valve & then right into the top of cylinder :(((( motor is DONE!  it currently has a factory mercruiser 302 (old motor).  It came with 188hp, boat is sloooooooow... lol    Now that iv got to put a motor in it, Im REALLY considering a performance 302 with 300hp.  thats 112hp more then before,  will i be ok??????? lol.  the boat its self is VERY SOLID, handles VERY ruff seas! outdrive is fresh,  last thing this old heavy tank needs is an engine... o and exhaust manifolds, o and 4 barrel carb, o and intake, o and....... lol

[seabob4]

Well, first, welcome aboard!!  Now, are you sure your old motor is a 302 (Ford)?  I don't ever remember Merc using Ford blocks.  Now if you are looking at upgrading to 300 HP, that would be a Merc 350 MAG...which of course is a Chevy 350 block.  Sure your old motor isn't a 305?

The 350 MAG can mate up to an Alpha 1 outdrive, which is what you probably have already.  But it would be better to swap over to a Bravo 1 drive, can swing a bigger prop.  Alphas are kinda limited...

[seabob4]

Just did some research, the last year Ford supplied blocks to Merc was '77...so it MIGHT be a leftover 302...

[dburr]

350 mag and a Bravo III would be something!   :twisted:   Spending other peoples money is fun!!

[seabob4]

350 mag and a Bravo III would be something!   :twisted:   Spending other peoples money is fun!!

Yep and yep...

[fitz73222]

It would be interesting to understand how a 300HP street 302 is cam'd and will it have any bottom end for marine use? Where is the 300 HP rated as far as RPM? I am assuming this is a street engine that needs to be converted to marine use. You may want to consider upping to a 351 for better torque and bottom end. Keep the same bell housing so the swap is easier. You need good torque at about 3200 rpm which would be a cruise sweet spot in my estimation.

[1998z28]

I for sure its a 302,  with 351 heads.   the motor im looking at getting is from ( us engines Inc) its  a true marine motor,  I want to stay Ford just because I just bought new marine grade starter, water pump, alternater.  If I swapped to a Chevy motor I'd have to buy new EVERYTHING:((( lol.  O im not a Ford guy!!!!  GM to the bone....lol

[GoneFission]

Go to a 351C if you can find one - these can easily be built to over 300HP and run on regular fuel.  Another option would be to upgrade to a more modern 5.0 Ford with EFI, but those are a bit wide and might not fit in the same spot...  Here's a 351C crate motor on eBay for ideas:
http://www.ebay.com/itm/FORD-351C-340-H ... d2&vxp=mtr

[1998z28]

Thanks il check that 351c out!  what ever i do im not putting in another engine that is only 188hp lol poop on that idea... lolol,  the boat was so under powered before, that i had to put a 17 pitch prop on it just so i could get it up on plain before 100 yards lol. top speed was 34mph with the old motor,  took 5 miles to get there to!

[SaltH2OHokie]

Thanks il check that 351c out!  what ever i do im not putting in another engine that is only 188hp lol poop on that idea... lolol,  the boat was so under powered before, that i had to put a 17 pitch prop on it just so i could get it up on plain before 100 yards lol. top speed was 34mph with the old motor,  took 5 miles to get there to!

I'd definitely give some thought to going 350 (gm) purely because you'll have a much wider selection of motors, easier time finding motors and parts, and because you said you loved gm :-)

4.3 and 5.7 are pretty much the I/O standards now from what I can see.

I swapped a 351 out for a 350 on my correct craft and never looked back, purely due to lack of available marinized Fords.

[seabob4]

The 4.3 Vortec is a killer motor for a V-6, and of course, the venerable 350 MAG, 300 honest HP from a SB.  But stepping into a B1 or B3 drive (which the 350 Mag can swing) is the way to go.  As Ryan said earlier, a B3 drive is sweet, makes handling at slow speeds EASY, not to mention docking and hole shot...

[dbiscayne]

I for sure its a 302, with 351 heads. the motor im looking at getting is from ( us engines Inc) its a true marine motor,

Get some more info on that 302/300hp before you pull the trigger - I've been messing w car engines for quite a while, and sure 300hp can be had outa that 302 but it might be winding up pretty good, and....Ford never made 351 Windsor specific heads, unfortuanately just the opposite is true they used 302 sized heads (small ports, small valves) on a 351W block, since day one including on the marine engines.  Choked the 351W's pretty good kept them from making decent power up hi in the rpm range.  Factory GT-40 and GT-40P heads breathe better but are still small for a 351.  They've got a pretty good write up on the US Engines Inc site but no specific info?
Ask for cam specs and a dyno slip on the 302, and what brand of heads are used.
Afermarket heads are another story, and that could be what the 302/300 has.  Bolt on an easy 50hp over stock with a head swap, but theres good and bad aftermarket heads so do some research there.

351 Clevelands, and 351 M blocks different story, use better factory heads.  But don't bother with either of those, parts are rare and they're a very inefficient design great for racing but thats about it.  The 351C's were also relatively 'thin' around the cylinder walls, not a good candidate for a boat engine as they suffer from running hot, most people get the blocks sonic checked for wall thickness before screwing with them they don't last long if the cylinders have been bored.  They're also quite a bit heavier than a 302/351W engine.

A 351W is an easy bolt in swap for a 302, same bellhousing bolt pattern which is the most important thing for car guys maybe not so much in the outdrive world, front accessories almost the block is just a little taller so you'd need a different alternator bracket, same exhaust bolt pattern cause the heads are the same.    Different distributor, intake, oil pan.  Will a taller block screw up your exhaust alignment?  Throttle linkage?  It's less than 1/2" taller.
351C engines have the same bellhousing pattern but after that they're completely different everywhere, and physically bigger.

Like someone already said you don't want a hi winding engine thats sluggish down low where you need it to get up on plane.  Good torque to 3000 rpm, max hp around 4000 is probably good but I'm not an inboard guy just guessing.  A 350ish cubic inch sized engine is also going to give you about 50 more hp and lb/ft torque over a 302.

One last thing to consider, but very important to get right, is the older 302's and 351W's used a 28oz balancer, the newer 302's/5.0 engines use a 50oz balancer.  On a car setup the balancer has to match with the flexplate or flywheel in the transmission, not sure what it's mated to in the marine setup but there should be something???  This isn't something you can just convert on the engine, the crankshaft is specific as well as the harmonic balancer.

Whatever you end up with make sure it's truly a marinized engine, not just some half converted car engine thats gonna rust up on ya.

[TheKid]

May not be up your alley, or in your pocket book, but I would like to plug that hole in the transom, add a bracket and a 200-250hp E-tec.

That would give you a huge dance floor.

That is my ultimate plan, but more work for me as I have to build up the transom and ditch the splashwell.