Bored over 390

[freeline95]

I bought a 390 off of a guy and he told me that It was bored over by 40 is their any way for me to tell if it really is or not? I heard that you could read or see something either on the piston caps, or on the top of the piston itself. Wasn't really sure so I figured that I would ask some people that I know would know.

[1971ford]

im no engine guru but it should say on the top of the piston and depending on the machine shop it could be stamped on the block letting other shops know it is bored. Thats how my 360 is. The PO said the engine had never been apart, however the block was stamped .030 over and sure enough the pistons agreed.

[fordman]

use a micrometer and measure the bore.

[DuckRyder]

Going to be hard to see if it has been run much, but yes the pistons should have the oversize stamped on the top. You can try looking down a spark plug hole with a good flashlight and see what you can see. Otherwise puling a head and measuring is about your only option.

[freeline95]

well that sucks because I really didn't want to take the head off because its a perfectly good motor with all new gaskets that the other guy put on and it has no oil leaks. So I guess that if it is or not will half to do because I was going to pull the oil pan to look at the piston caps because it was quick and easy but oh well. Thanks for the info guys.

[sideoilerfe]

If it is a perfectly running motor than why bother with it? If it runs good then just drive it.