Allright, i was wondering if all 6 block plugs on a '64 390 are the same size or not.

I had one blow out on me so I put one of those rubber expanding ones in there to get myself home, but i started thinking that if I'm going to have to put a plug up in there anyway i might as well put an engine block heater in while I'm at it.

Deal is, all the ones I can find say they should be installed in the right center plug. Issue here is 1) it's not the one that came out and 2) there is no way a block heater could go in there due to the motor mount.

Do they just recommend to put it there for efficiency's sake, or is the center plug a different size from the others?

The one that came out is the right front on and i know for a fact it's a tad over 1 3/4" (1 49/64").

Justin