GM Performance block - MAX BORE

[3dinter]

I was looking at getting a new block from GM, i cant access the number right now, buts its the basic 350, 2 piece seal, 4 bolt main block for like $ 799 from summit racing. I looked at the GM performance catalog and this block states that the max bore is 30 over. i called 2 local gm places and asked if the MAX BORE is 30 over and they could not answer the question.
Does anyone have experieince with this block and what is the true MAX BORE this block can take ??

[Eamsnewbie]

i dont think you will find anyone saying its okay to bore 60 over. I would try and locate a block casting number of 3970010 and bore it 60 over. urban legend has it that they have more room to bore and the composition of the material is better.

[CNC BLOCKS]

I have bought the 336 castings over the years and after a sonic had to send a few back because of thin cylinder walls to start with.

Remember they are made in Mexico now.

[3dinter]

i dont think you will find anyone saying its okay to bore 60 over. I would try and locate a block casting number of 3970010 and bore it 60 over. urban legend has it that they have more room to bore and the composition of the material is better.

funny you mention that # 3970010...im tearing it apart as we speak...its a stock bore from like 71 /72 big chevy work truck the stock pully up front was like cast iron and weighed liked 20 lbs with 5 grooves for belts.....the machine shop guy i took it to at lunch today says we might can do 30 or 40 over bore on it and its got a stock steel crank...i have to measure when i get it out....i dont like to go 60 on a stock gm block this old.

[3dinter]

I have bought the 336 castings over the years and after a sonic had to send a few back because of thin cylinder walls to start with.

Remember they are made in Mexico now.

i forget about the mexican castings now adays....hopefuly my 3970010 will clean up real nice....

[Eamsnewbie]

i forget about the mexican castings now adays....hopefuly my 3970010 will clean up real nice....

The 70s block 010 is American made no "henco Mexico" stuff if heard the have a higher nickel content and I've heard they don't. They've always been good block for me. And for 140 bucks at pull a part you can't beat it. And that for the whole motor

[CNC BLOCKS]

funny you mention that # 3970010...im tearing it apart as we speak...its a stock bore from like 71 /72 big chevy work truck the stock pully up front was like cast iron and weighed liked 20 lbs with 5 grooves for belts.....the machine shop guy i took it to at lunch today says we might can do 30 or 40 over bore on it and its got a stock steel crank...i have to measure when i get it out....i dont like to go 60 on a stock gm block this old.

Any GM block needs to b sonic tested before any work is done and check if that block has 2482 on the center caps.

[3dinter]

Any GM block needs to b sonic tested before any work is done and check if that block has 2482 on the center caps.

i just dropped it off today to the machine shop for checking out....there was some kinda numbers on the caps..i didnt pay it no attention...what would the 2482 mean ??

[3dinter]

The 70s block 010 is American made no "henco Mexico" stuff if heard the have a higher nickel content and I've heard they don't. They've always been good block for me. And for 140 bucks at pull a part you can't beat it. And that for the whole motor

i actually got it for a swap of some other race car junk....

[CNC BLOCKS]

i just dropped it off today to the machine shop for checking out....there was some kinda numbers on the caps..i didnt pay it no attention...what would the 2482 mean ??

They are the nodualr iron caps that GM used on truck engines and performance engines and some marine engines as well.