i have been doing alot of reading about mopar small blocks and everyone seems to covet the almost extinct 340 with its large bore but the crank is the same as the 318.my question is if i take a 360 block bore it 40 giving it the same bore as the 340 and then use the 318 or 340 crank and rods wouldnt i have a 340 or would it be better to just build a 360

 

I do not see why you would want to give up the extra stroke of the 360. The 340 is a better high reving engine than a 360, but the longer stroke on the 360 will give you more low RPM grunt. The early 340s had 2.02 intake valves and a fairly bumby cam. 4speed motors were even a bit bumpier then the 727 equipted cars. Bore your 360, Use good heads with 2.02 valves and a good cam grind and you shouldn't be disapointed. remember there is no substitute for cubic inches !

 

I say build the 360.

There are more scientific folk who get into "bore to stroke ratio" which in part why the popular Chivvy 383 was born. I believe we can thank Grumpy Jenkins -- a long time ago -- for that.

Here's one:

http://www.driventomodify.com/showthread.php?t=7242

 

The main journal diameters are very different. Do the 360 with big heads, make 400 hp and have fun. If you want a screamer do a 318 with that 3.31 stroke make 300-350 hp and have fun. If you got lots of bucks get 500 hp out of a 318. Oh, and have fun.

 

Having had both ! 340 would be preferred, high rever STEEL crank different rod ratio. !!! 360 can be built just as well..