A friend has a 3963512 cast big block and wants to know if he can safely bore it .125 over.

Anyone?


TIA

No one here will be able to say for sure. :noway:
He'll need to have that block sonic checked by a local machine shop.
It all depends on the core shift on that specific block.

A friend has a 3963512 cast big block and wants to know if he can safely bore it .125 over.

Anyone?


TIA

None of those 512's are safe at .125" over. It would take some "concrete" to make it reliable. Also in a street application, you have to remember the more "metal" you remove from the bores, the more temp-control problems you will run into!

Thanks, Gary in N.Y.

P.S. Now let me add this here. Before you post a block number you intend to build upon, it would very wise in today's marketplace to check on the value of the part first. Depending on the date AND condition of the casting, you may find some shops like my own that would make a "heads-up" trade for possibly a new "Bow-Tie" or "Dart" 4.500". The resto business has us "buried" in units awaiting to be done. Personally I have a 3 month backlog as of today. Those 512's, 942's, 351's, etc, are worth their weight in gold, so to speak. The 351's specifically will fetch in the area of 6000.00/7000.00. Again, depending on the dates. As I said, to trade any of these for an aftermarket block is a huge "score"!!!

Thanks guys, its for all out racing application, but I doubt he wants to fill the block.

I kind of figured that was way too much but when he asked I figured you guys would have the definative answers.

Again, Thank you for your help.

Listen to Gary. No reason to kill a 512 block racing when someone will give you enough money for it to buy a much better block.

I was assuming the -512 block was already at +.100" (because of the +.125" inquiry) and not really worth a whole lot to any "numbers" guy. :(

I don't know if the block has been touched or not.

I was just a go between asking the question, but again I do appreciate the information and have relayed it to the owner.

And don't forget, they can be sleeved back to stock bore if desired, right Gary..

pdq67

And don't forget, they can be sleeved back to stock bore if desired, right Gary..

pdq67

Hi Paul, exactly correct. Let me tell you about a block here now for a BB Vette resto. It has 8 sleeves, it has about .050" missing from the decks, it has about 18 "deck plugs" to repair bad head bolt holes, not heli-coils but actual plugs, it has all 16 lifter bores ready to be bushed, and it has 5 different main caps installed. This block sold for to the customer for over $2000.00.

Simply because it had the "right" dates cast into it!!! That's why I tell you guy's up here to do your homework.

Up until last year we could get any cast block/head welded the correct way with a full 100% guarantee, no matter how bad the core seemed!

(Add) On the #351 blocks, a "mint" block dated right and "untouched" would be worth 3+ "Bow-Tie" blocks from G.M. brand new! All this "mess" caused by folks with large amounts of money seems to be finally settling down some. There are probably more 427/435 Vettes "registered" now than what G.M. produced in the beginning.

Thanks, Gary in N.Y.

P.S. If anyone is wondering about the "missing" deck surface, Cometic just put together a pair of head gaskets for this job to the tune of $450.00 (resale) with freight!