[73 ski nautique]

Not a Mustang question, but I'm betting you guys have forgotten more about Ford SB's than I'll ever know. I have a reverse rotation 351w in my vintage ski boat. The previous owner was less than forthcoming about the motor. Long story short it was pumping oil out the dipstick tube, Pulling the heads revealed the problem to be the #7 bore was severely pitted and eroded from water sitting in it, apparently for a long time.

Rather than boring that block, I've acquired another reverse rotation shortblock casting #d9ae 6015 ed15 il4. The original block is still in the boat, I can't see the casting #. I'm assuming its the original 1972 block. Were there any changes that would keep me from swapping all the parts over? Oil pan, timing cover, etc, etc...

I'm also looking for a bit more power and have a set of shorty wet headers, performer intake, gt40p heads with bigger valves and 1.7 rr's, I'm going to do a cam upgrade within the limits of the wet exhaust. I'm looking for broad flat torque up to 5200-5300 rpm.

What do you guys think?

[2+2GT]

I've done some boat motors. Use Roades lifters. You can use a hotter cam and still come up to the dock at 400 rpm.

I'm not clear why the block would be any different for reverse rotation.

The GT40 head was developed from the 351W head. Just rework those.

[73 ski nautique]

The heads on the 351w are not original, they are mid 80's truck heads, small valves, open chambers, low compression. The gt 40p's get compression to the 9.3 range, better runners, better plug location, flow better.

I was not really asking if the reverse rotation made a difference, but if there were any other changes that would make the parts not swap. Any changes to the casting of the block?

The heads, intake and cam should get be above 300hp.

Thanks

[ashford]

the only difference in those two blocks are (assuming previous block is 72 and older) is the main caps have the bearing retaining notch in a different spot and a larger od on the main rear seal. the only other difference is the older blocks have a little more meat in the main webbing(not really a concern unless your well above 500 hp)

[73 ski nautique]

So if the rear main seal is a larger diameter, will my early oil pan fit the later block?

[ashford]

Originally Posted by 73 ski nautique

So if the rear main seal is a larger diameter, will my early oil pan fit the later block?

yes

rear main changed around 74 the difference is in the main cap and block where the seal goes not the oil pan groove

[73 ski nautique]

Thank you.