Dearborn eaton interceptor

hello,
new to this forum and hoping someone can help. I have a 1959 Henry wooden lapstrake with an inline 6 cylinder Dearborn Eaton Interceptor. from what I can tell, it is an 85hp serial number on engine is M42013P, number on the transmission is
M93R213575. looking for an engine block, it has the three freeze plugs on side of block.
My question is this,
how do I know if it is a 144 cu inch or 170 cu inch? is this the same block in the 60s falcons?

Hi there Sam B!
Dearborn interceptor engines are all Ford car engines modified for marine use. The blocks, pistons, cranks, etc are all automotive your engine may have a marine canshaft oil pump, and a few other parts to make it spin in the reverse direction (RH looking forward from the flywheel).

On your block behind the timing cover on the distributor side of the engine, you should see a small "N" or a "T" the "N" indicates 144 CID, the "T" is 170 CID.

Find the casting number on the block and start shopping for rebuild parts. I'd suggest you disassemble the motor and have the block and head boiled, backed and magnafluxed before I bought any parts. Everything but the cam will be easy enough to find. If you need a new one, you will need one custom ground as it would be a freaky stroke of luck to find one.

Good Luck!