After discovering a cracked block in my project 58 C1 I spent a lot of time looking for a replacement block and am not sure if I was too picky but I wanted one that would make .030 over.

Depending on who you talk to I have heard on several occasions that .060 over you run the risk of the motor running hot and possible overheating issues. Is this a myth or not.........?

The other thing I find amazing is that anyone would pay any money for a block or heads that have not been properly tested for cracks. I watch Ebay and am shocked at how many "known good" engines and heads are sold for a premium without any testing. I have heard that line twice and refuese to buy anything unless I get a written guarentee that if there is a crack they will take it back.

Luckily I ended up finding a correct block that will make .030 over!

Chris

 

I got a .060 bore in my 60 283. No problems. I also have a Dewitts alm. radiator.

 

The .60 overbore issue on 283's in a non issue. You can go .125 over and not "run hot" if the cooling system in the automobile is functioning correctly.

Rich

 

Back then most all the 283 blocks had thick enough cylinder walls to go an 1/8" over making the finest of all small blocks, the 301.

Back then the only real problem was the somewhat weak connecting rod with a pressed in piston pin. They had a propensity to 'walk' into the cylinder wall at high revs.

 

I agree with Carl (67L36 driver). The problem is not so much whether the motor will overheat with a .060 overbore as it is whether or not you will have a thin wall problem due to core shift. When they poured the blocks at the foundry occasionally the quality of the casting would be such that the location of a cylinder would be so far off that during the machining process you could wind up with a perfectly good bore but a very thin wall.
The 265 and 283 blocks were frequently bored .125 over with success but you were always at risk with the process.

A story to illustrate my point:
In 1969 I built a 302 SBC to run in Modified Production in a 57 Chevy. I bought a brand new Z-28 302 4 bolt main bare block from GM. After pulling the freeze plugs and oil galley plugs I sent it out to a machine shop for align honing the cylinders, align boring the mains, trueing the deck and etc., the usual things you would do in building a racing motor. I got a phone call from the owner of the machine shop who told me I had a hole in the bore of one of the cylinders... Right through to the water jacket. He was not boring it just align honing and fitting each individual piston. He was removing material in the tenths (4 decimal places) how could this happen? I was not happy and GM after much "discussion" finally agreed to replace the block but I had to eat all of the machining costs. Core shift cost me a lot of money and time.
Going .060 over isn't much of a risk and I suppose to use your correct block it is worth it with sleeving a possible remedy for a driver motor but it is something you may want to keep in the back of your mind.

Best Regards,

Ralph

 

I had my 59's 283 sonic checked and then had it bored to 4.00". My machinist told me it was safe to go another .030" over. My block had two sleeves in it before I started, but the machinist wasn't concerned about them.