Same block, different bore???

[MTmopars]

Please school me on this. If you have a family of engines, why can we only take smaller bore variants to .060 over? For example. We can bore a 340 .060 over, why can't a 318 be bored to the same?

 

[RustyRatRod]

Please school me on this. If you have a family of engines, why can we only take smaller bore variants to .060 over? For example. We can bore a 340 .060 over, why can't a 318 be bored to the same?

They can.......sorta. Hensely Motorsports has been boring 318s .090 over for better than 20 years making 402 crate engines out of them with 4" stroker cranks.

Now, if you're asking since a 340 can be bored .060 over then why can't the 318 then the answer is you surely can. A 318 will go .060 without lookin back. ....but I don't think that's what you meant.

Of course, if you plan on boring a 318 to 4", sonic checking is a must, which Hensely does.

 

[MTmopars]

That is what I am saying. if a 340 can be bored to .60 over, why couldnt a 318 be bored to 4.1" provided it sonic checks.

 

[C130 Chief]

Because the cylinder "tubes" were smaller on a 318. Or, more accurately, the casting sand cores were larger. Sand is cheaper than iron...

 

[MTmopars]

So the internal voids betweent the block walls and cylinder walls are different?

 

[replicaracer43]

so the internal voids betweent the block walls and cylinder walls are different?

yes