Hey guys,
I have a 1972 340 block that needs a sleeve in one cylinder and will have to end up at .060" overbore. Is this thing worth keeping around or should I put it in the scrap bin ? I don't know how the wall thickness is on these things and if a 72 block is anything that restoration guys would be interested in. I can borrow a sonic tester and check it if it might be worth something.

Any thoughts ?

 

Not sure what it would be worth. But I'm sure someone would re-sleeve it and could use it if they had some spare parts laying around. I know I would.
See you at the Races !!!!

 

Do not scrap, post for sale on For A Bodies Only forum and you will get a buyer.

 

Thanks,
I am going to sonic test it and see how thick the cylinder walls are. If they are ok I might go ahead and put the sleeve in it and finish it. All I would have invested is my time and the price of the sleeve. I think it would sell a lot easier as a ready to run deal

 

I would not bore the cylinders this should be done to the pistons. It also gives the option of 40 over as apposed to 60. You might bore the sleeve to the rest of the block but don't go farther. I wouldn't want a block that was bored ready for pistons.

 

The block is already .040 and worn pretty good. It is absolutely going to have to go .060" As far as boring to the pistons goes that is pretty much ancient history. With modern pistons if you size the bore to the correct bore size the clearance will be correct. It actually has always been that way but 40 years ago the manufacturing was not that great and you did have to check them all. I probably do three blocks a week and I don't think I have seen piston made incorrectly in the last 20 years or so. There is always the possibility that you want more clearance for a supercharged or nitrous application but that is maybe 1% of the engines out there.

I always prefer to have the piston in hand but in this day and age it really is not necessary except for special applications.

 

My shop won't bore a block with out the pistons for the reason I've stated, I'm going to ask them about it.

 

Don't get me wrong, it is always preferred to have the pistons but when you talk to them ask them when the last time was they had a piston that did not have the proper clearance machined into it Modern technology has made it so that even the stock replacement Sealed Power and Mahle pistons that are $8 a piece are machined better than any race part you could find back in the 60's. Just like any other part it is always best to check it but it is VERY rare to find one wrong now days.

Pistons have always been manufactured to fit in a stock bore size or standard oversizes. The clearance is machined into the piston. Some engine builders might want to run more or less clearance for very specific combinations but in general if you finish the bore to the correct size it will be fine.

 

I think those blocks are thick enough in the web and bore to be able to even sleeve it back down to a stock bore size if needed. It sounds like it is seasoned enough to be squared up and would do someone a really nice engine. Make a nice little 10.5.1 CR with some J-Heads or Edelbrock heads..