Hi, I'm taking my 350 block to the machine shop in a few days; since small blocks aren't to popular in Poland, it's hard to find full data sheet for machining. Do you know where can I find this info online? I'm actually interested in bore dia. tolerances; what are max. +/- variations? (yeh, this may not be a proper word, still learning...)

 

The most I would ever go on a 350 is .060 over.

Thats what my motor is at, and to everyones disbelief, I don't have cooling problems.

 

bore on a 350 is 4.00 taper and out of round max spec are .002. stroke is 3.48
main is 2.4484 to 2.4494
pins 2.0986 to 2.0998

i'd be looking for a manual and not trusting info i got from someone on line

 

I've checked in Chilton's book; there're all the values you've mentioned; but there's nothing like for example:

- bore, 3rd oversize: nominal dia 4.030" min. size 4.028", max. size 4.032"

Thats why I'm asking. Thanks anyway!

Mike

 

If you're going oversized (30-over, 40-over, 60-over) you match the bore size to the pistons you are using, but I don't just mean in the very general way that we're all familiar with. I mean, you buy your chosen oversized pistons FIRST, measure them and then have the machine shop bore/hone the cylinder to be just slightly larger than the piston by whatever the piston-to-bore clearance spec is for the brand/type of pistons you are using.

Typically, oversize pistons come out of the box right at their stated diameter or ever so slightly smaller. A 30-over aftermarket piston would typically be around 4.029-4.030"

If those pistons call for a cylinder-to-bore clearance spec of, say, .002" then the bore of the block would need to be taken out to 4.031-4.032" to achieve the correct piston-to-bore clearance with those pistons.

Make sense?

 

^ That is the correct way to do it.

 

This must be the best way; I'll wait then till new pistons arrive (Sealed Power H631CP30), thanks