WEll, i got sick of feeding it as much oil as gas so i yanked it for a rebuild. So far i have the heads off and it looks as if there is 040 stamped on the pistons.....can you bore a 401 60 over? I"ll try to keep you updated.o No:
Kinda curious myself, how thick the 401'' and 425" cylinders are...at least, compared to 350's and 455's.
My '66 4speed hardtop motor was pretty worn out when I bought it, from drag racing. I had to bore it .060, and have never had a problem. I wouldn't go any farther, though. Dan
to bore or not to bore? Hey guys, I just built a nailhead 401 to .060" over. I have 3000 miles on it and not a problem with the cooling. I think the absolute minimum thickness is .180" on the walls, I will have to check and get back to you. If you Ultrasound (Sonic Check as the Engine builders call it) the cylinders, you will be fine.
