I am contemplating turning my daughter's 352 into a 390. I found 390 crank, rods and pistons with only 4000 miles, but the pistons are .060 over for the 390. Can anyone tell me what is considered a "safe" bore on a 352 block? The block is out of a 1966 ford F150 (if that makes any difference). I am interested in any and all opinions. Thank you.

 

Only a measurement of your block is going to tell.

Maybe you just get some standard 390 pistons and do the minimum boring.

 

+.060" on a 390 will equal +.110" on a 352. Unless the block is sonic tested I think the "safe" max overbore on any FE is generally considered to be +.060".

 

390 @ .060 is 4.11, very close to a 4.130 __ are you sure you have a 390?

If the 352 is std bore, then a .050 extension is all that is needed. Scrap the .060 390 slugs and get a std set for cheap. Used .060 slugs wont be worth the time/effort in a 352 overbore unless the core is 1 in a 1,000,00. Converting a 352 to a 390 is a cheap and viable option. Starting at stock leaves the possibility of another rebuild, ask the machinist about the bore options. Heat transfer is an issue in short order so opt for minimal OB. imo... a std 390 will be a big improvement on the tired 352

keep us posted.