Boring out 390 motor
I am currently restoring a 68 Mustand Fastback (Eleanor) and I have a 390 's' code motor. It has a FE Y Block with the numbers 352 stamped on it. I recently had it rebuilt and the block was bored out an extra 60 thou. After being started only the times the block has cracked. I have received differing information from various sources and I really need to clear up exactly whats going on here. I've been told that if you bore the 390 out 60 thou it is gaurenteed to crack, but then I have also been told that while the 427 was originally brought out with a different size block, when these were blown up the same block from the 390 was used. If this is so then surely boring it out 60 thou shouldn't cause it to crack. Personally I beleive that water inside the motor was the cause (no it wasn't me who put the water in it!) but I need to be absolutely certain before I go doing the same thing again.