3970010… but it’s a 305?!?!

[Island’r]

Originally Posted by cadillac_al

There never was any such thing as a 305 with an 010 block.

That’s why the suffix code & story from the previous owner have always perplexed me… Why would anyone try and sell a 350 as a 305…

It’s usually the other way around

[CC69Rat]

The more desirable 0010 blocks will have 010 / 020 stamped in the block behind the timing gear. That's the high nickel blocks, the one to build just for a good solid street motor. A lot of dirt trackers like them too. They make really good foundations for stroker builds.

But not all 3970010 blocks are what I'd call rare or desirable. As mentioned it could be a 2 bolt or 4 bolt and they made a billion of them. The high nickel blocks are definitely one to get though.

But I haven't ever seen a 305ci 3970010 block. Could it be a 302 + .0030? Maybe they bored it? Not saying it doesn't exist, just saying I've never seen one personally.

[kwmech]

The 3970010 block is a block cast for a 4'' bore--PERIOD. the only way to get a 305 out of this block is to sleeve all 8 cylinders. A 305 block has a 3.75 bore or 3.743 to be exact

[RustyPile]

Originally Posted by kwmech

The 3970010 block is a block cast for a 4'' bore--PERIOD. the only way to get a 305 out of this block is to sleeve all 8 cylinders. A 305 block has a 3.75 bore or 3.743 to be exact

I suspect what we have here is some previous owner's vain attempt at making a replacement engine "numbers matching" by re-stamping the engine code......

[mattfranklin]

Originally Posted by cadillac_al

There never was any such thing as a 305 with an 010 block.

Unless they were short of proper 305 blocks at the factory, and sleeved a 350 down to the ~3 3/4" bore of a 305. So unlikely, though.

[Island’r]

Update: I’m installing new headers and found these casting marks on the passenger side:

https://ibb.co/W0qjsC0