340 Blocks

[bvfs12]

I have a simple question.

Is there any differences between the 340 blocks between the 1969-1973 years or are they all the same ? Is any year block better than another ?

 

[1970Duster]

Some had thicker cylinder walls allowing for larger bores and some (t/a) blocks had thicker webs allowing for 4 bolt mains. Other then that they're the same you can make them either external (way?) or internal balance it your pick. I have a 72/3 block (external balance) and made it internal balance.

 

[Coyote Jack]

I'm not sure how true it is, but the theory is that if you look at the numbers on the drivers side of the block, they might end with "340-6" or something like that, the lower the last number the better the block should be. ie: a 340-1 would be better than a 340-6. The last number is supposed to represent how many times the casting mold was used.

Jack

 

[pishta]

I'm not sure how true it is, but the theory is that if you look at the numbers on the drivers side of the block, they might end with "340-6" or something like that, the lower the last number the better the block should be. ie: a 340-1 would be better than a 340-6. The last number is supposed to represent how many times the casting mold was used.

Jack

That is true to a point. The 340-1 (sort of like a V1.1) might be inferior to the 340-8 (V1.8) because the casting revision "8" (not number of times it was used) may include slight changes that were needed for manufacturing, eg. a thicker casting rib or a bolt boss or a core shift tweaking, etc. Although most blocks are identical in almost every way, the 400CID Mopar for example had one block that had a noticeably thicker web on the #3 bearing. Check out 440source.com for their theory on casting core numbering. I had a "340-6" block and was doing backflips until I realized it was just the 6th core revision, not a 340 six pack T/A block......

 

[Rodzilla]

I've heard the 72/73 blocks are best wih the least amount of coreshift. I have a 73 that I'm using for my 416, and my machinist said he never seen a better 340 to start with in his 30 yrs in the bizz. I thought all 340s were internally balanced, never heard otherwise but I could be wrong. 72/73 had the cast crank, but who cares when building a stroker

 

[Wheels]

1968 to 73 340 blocks are all the same, Casting #2780930
1970 340 T/A block casting #3577130 more metal was added to the main bearing supports (thicker) for strength and to allow a 4 bolt cap to be used.
And lets not forget the "X" block the mopar preformance race block.

Cheers.