Noob - Does anyone know the head casting on the 1987 OMC 5.7 GM engine?

[Barrett50]

I have inherited at 1987 Glastron-Carlson CVX-23 cruiser and trailer. The engine is locked up, and I don't want to check but almost sure the block is cracked. I have a good rebuilt GM 400 short block, and planning to mate my heads, intake, etc to the existing 400 block, with drilling steam holes in my heads. If you have any info on the OMC 5.7 heads, please share. This is the 4bbl carb engine, I think 260HP with the Cobra drive.

Also, please don't advise on spending $1.3M and throw away all my current goods. I'm not going that direction. The 400 has dish pistons, so I'm hoping these head castings have small chambers around 61-67. Not interested in buying Vortec heads, Dart, race, etc. The Cobra barely supports 260HP, and my next change will be the Merc Alpha swap kit for the cobra leg.

 

[Barrett50]

Well, now I feel even more dumb that 33 min ago. My son, who knows nothing about boat engines put my req into a 'chatGPT' search and it spit out the info about 2 seconds later:

Typical specifications:

• Casting number: 14096217
• Combustion chamber: 64 cc
• Intake valve: 1.94 in
• Exhaust valve: 1.50 in
• Valve covers: Center-bolt
• Intake bolt pattern: 72° center-bolt intake pattern
• Material: Cast iron

So, looks like I'll be using the free AI search for stuff like this. The heads are going to work ok, but my C/R is going to be pretty low with dish pistons. I may have the shop cut them down to around 56cc to make 8.8-1. Might also open up the valves to 2.02/1.61 while I'm at it and have the steam holes drilled right.

argh, technology is an amazing thing.

 

[bondo]

I have inherited at 1987 Glastron-Carlson CVX-23 cruiser and trailer. The engine is locked up, and I don't want to check but almost sure the block is cracked. I have a good rebuilt GM 400 short block, and planning to mate my heads, intake, etc to the existing 400 block, with drilling steam holes in my heads. If you have any info on the OMC 5.7 heads, please share. This is the 4bbl carb engine, I think 260HP with the Cobra drive.

Also, please don't advise on spending $1.3M and throw away all my current goods. I'm not going that direction. The 400 has dish pistons, so I'm hoping these head castings have small chambers around 61-67. Not interested in buying Vortec heads, Dart, race, etc. The Cobra barely supports 260HP, and my next change will be the Merc Alpha swap kit for the cobra leg.

Ayuh,...... Yer headed for problems,..... The 400 has bigger mains, 'n bigger crank flange,.... yer OMC coupler won't bolt onto the 400 crankshaft,....