Boring a 318.Tranny ID

[drnempho]

Can a 318 be bored to take a 340 piston?How far can it go if not?And how do I find the numbers for what transmission I have?For example, I have a 4 speed automatic out of a 89 150.What is it.Like a 500?I also have a 3 speed out of the same year.They both need rebuilt but I mainly want the 4 speed.

[John Kunkel]

Like all other questions on overboring, the block must be sonic checked to see if it is suitable for a given overbore. Boring a 318 to 340 bore size would require a .130" over bore, about twice the average allowable maximum overbore. Forget it.
A 4-speed automatic out of an '89 would have to be an A500 since the A518 didn't come out until '90.

[Ausydad]

My 318 is bored over .060 to 3.97 and that is about as far as I would ever take it. Even then, you're looking at decking the block, going with 302 casting heads, or spending $600-800 for custom pistons to have a decent enough compression raio for a healthy SB. If you're close enough, I'll make you a sweet deal on a running 360. I can't afford to ship anything that big. Besides, I don't have a puller. You would have to bring that, too...