1967 Corvette Rat Motor

Hi Scotty, love your videos. I need your advise…

I have a racing boat with an engine that will not turn. I can’t turn the crank by hand.

Here is some info on the motor. It is very rare .

It is a 167 Corvette Rat motor. BB 3904351 427 4 bo0lt. I was told it is bored out 120 over. Approx 750 HP.

Last summer I blew a freeze plug on the passenger side, the second freeze plug starting in the back going to the front of the motor. I found out that the freeze plug was a cheep and not the right one as far as the height if it. (the “walls” of the bowl, if you will, where not tall enough. Made in Japan, I think. Replaced it and tried to start it. Something is “locked up”.

I started to pull the plugs and they were difficult to loosen up. They were rusty and crusted with crap. I don’t know if was melted metal or piston material or ? So I squirted a few pumps of oil in each of the spark plug holes. ( on the passenger side).

I pulled the valve cover, looks ok.

Need advise. Thank you. Ralph in San Diego, CA

No. 1-1

Beautiful engine, one could always just sit and look at it as Art. I would start with a good borescope and look inside the engine and attempt to crank it over by hand. If you can't crank it over by hand 360 degrees, then engine will need to be torn down to find the failure, no way past that. good luck