Ford 302 to 351?

[david84660]

I am restoring a 1973 Colbalt 18' Tri Hull that has been a family boat for, well....ever since 1973. It has a Ford 302 coupled with a Volvo 270 Outdrive (back then it was called Waukesha, not sure why). The engine needs to be replaced and I would like to upgrade to a 351 if possible. Does anyone know if this will be an easy task? are the blocks the same? will my 302 intake manifold work with a 351? I am not a Ford man as you can tell. Thanks for any responce I get.

 

[windsors03cobra]

Re: Ford 302 to 351?

No a 302 intake will not fit on a 351, a 351 while 90% the same as the 302 has a taller deck height and thus the heads are wider apart rendering the 302 intake to narrow.
Intakes are cheap and so are 351 blocks, will it work ? I have no idea depends on what your exhaust connectors look like, among other things.
You can buy many stroker kits for the the Ford Windsor engine family, 347 is very popular and cost efficient.

 

[WizeOne]

Re: Ford 302 to 351?

a 351 would be too heavy, most likely too wide and too tall for your 18 ftr. You would also need a new distrib and a new oil pan, in addition to the intake manifold.

Do like windsors03cobra says and check out the 302 stroker options. Personally I would stick with a 331 as opposed to the 347. The 331 is enough to rip the transom out of your boat.

Stroking the 302 will let you re-use all of your current peripherals. Build that motor with 9-9.4:1 compression and there will be no stopping you. The 331 has a better rod ratio than the 347 and is easier on the cylinder walls. Plus it has a fully grooved oil ring that is not interupted by the wrist pin.

 

[Apollo75]

Re: Ford 302 to 351?

The engines blocks are the same animal ---- the deck was raised 1.3 inches for a different crank and more cubic inches 351, the intake is wider, the oil pan is wider / rear main. Everything else should interchange from the blocks., etc,.

The exhaust will be a little higher and a little wider and I think there is a 30-lb difference in the overall weight. You do not have to displace much water for an extra 30-lbs

This is my next project too ----> I hope all goes well

Some great information about Ford engines in general.

http://en.wikipedia.org/wiki/Ford_Windsor_engine

This book has more than most want to know

http://books.google.com/books?id=VU1_G7trTLwC&pg=PA34&lpg=PA34&dq=ford+351w+heads+1975&source=bl&ots=gxvxc-vuVL&sig=iEICWG4Izs6kFKjI85rKKH47ByA&hl=en&ei=G6GfSoaNJpHqsQPK6LD0Dw&sa=X&oi=book_result&ct=result&resnum=2#v=onepage&q=ford%20351w%20heads%201975&f=false

I check the local library first.

OFM

 

[mkast]

Re: Ford 302 to 351?

One of the easiest upgrades I've ever been a part of.

 

[haulnazz15]

Re: Ford 302 to 351?

All has been said regarding the swap. You can find cheap 351 rebuilt marine longblocks. I have the 351 in mine (76 Mark Twain which is very similar style-wise to the Cobalt) and it is a strong motor. It was orignially rated at 233HP, but I am rebuilding it this fall to hopefully 300HP or so for a little extra kick. You can use the 2bbl carb from the 302 if you want, but I would just get an edelbrock performer intake and a 4bbl marine carb if you're going through all of the trouble.

I'm sure the 18ft Cobalt has plenty of room back there for the 351. The exhaust shouldn't be much different, but you may have to reprop it depending on your outdrive ratio. The 233 drive (pre-alpha I) was a 1.5:1 ratio, the 302's were a bit higher I think (1.8:1 maybe?).

 

[mkast]

Re: Ford 302 to 351?

302 engine used a 1.5 to 1 drive.
I have run into 351's using a 1.32 to 1 drive.
The project I was involved in used a regeared model 1 with the 1.32 to 1 gear ratio. The log style exhaust was changed to center riser.

 

[haulnazz15]

Re: Ford 302 to 351?

Yeah, I will also be attempting to go to a center-riser exhaust from the log-style, but we'll see if that works or not. It's a pretty pricey undertaking to get new manifolds and risers.