Anyone know how big.............?
um i hope you mean 4.060" and not 4.6". many people go .060" over with no problems and i think you should be safe. If it were me personally i would still only go .030 just for future rebuilds.
Nate
Nate
GM recomends that you only go .020, and I know there are alot of people that go .030, and .060. We believe that .030 is safe, but we strongly recomend you to sonic check your block before going 4.060. The reason for this is not all of the castings are the same. The thickness between cylinder walls and water pasages are a little thinner in some cases and can cause over heating problems. Not trying to scare you, we have finnal bored 6.0 blocks to 4.060 with out a problem. Just saying it's worth the added insurance to know that your block will go out to the bore size you want with no problems.
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From: Hazard Co. Maryland
Originally Posted by KJ@SDPC
GM recomends that you only go .020, and I know there are alot of people that go .030, and .060. We believe that .030 is safe, but we strongly recomend you to sonic check your block before going 4.060. The reason for this is not all of the castings are the same. The thickness between cylinder walls and water pasages are a little thinner in some cases and can cause over heating problems. Not trying to scare you, we have finnal bored 6.0 blocks to 4.060 with out a problem. Just saying it's worth the added insurance to know that your block will go out to the bore size you want with no problems.
Are we talking the LS2s (alum.) blocks are safe to bore that much? I didn't think you wanted to do much more than just clean them up.
Originally Posted by KJ@SDPC
GM recomends that you only go .020, and I know there are alot of people that go .030, and .060. We believe that .030 is safe, but we strongly recomend you to sonic check your block before going 4.060. The reason for this is not all of the castings are the same. The thickness between cylinder walls and water pasages are a little thinner in some cases and can cause over heating problems. Not trying to scare you, we have finnal bored 6.0 blocks to 4.060 with out a problem. Just saying it's worth the added insurance to know that your block will go out to the bore size you want with no problems.
I agree.
I wanted to go .060 as well, but after the sonic test .040 seemed like a wiser choice.
Also what can happen is if you do hurt the motor somehow at .060 you need a new block, but at .030 or .040 you can just bore it a little more and put it back together.
Originally Posted by sb427f-car
Are we talking the LS2s (alum.) blocks are safe to bore that much? I didn't think you wanted to do much more than just clean them up.
This is not for the LS2.
The LS2 can go nowhere near .030 over.
He is talking about the cast iron blocks.
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For the price of the block going under bore at .030 is just to be safe. If you have some issue where you need to rehone, then new pistons and rings would be needed also so I don't see how it saves anything more than the price of the block which is like 400 dollars. It took me two blocks and 90 dollar sonic tests for each to find a block to bore .060 safely. I had three cylinders offset bored by .020-.024. I would sonic test and offset bore even if I was only doing .030 over as some pin sides were only a little over .100 thick. That way wall thickness is maximized.
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Verdad Gallardo SSU'S Vice Mod
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From: Hazard Co. Maryland
Originally Posted by JZ'sTA
This is not for the LS2.
The LS2 can go nowhere near .030 over.
He is talking about the cast iron blocks.
The LS2 can go nowhere near .030 over.
He is talking about the cast iron blocks.
That's what I thought. Just with it being here instead of the LS1/6 forum, was a bit thrown off.
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From: Hazard Co. Maryland
Originally Posted by strokedls1
For the price of the block going under bore at .030 is just to be safe. If you have some issue where you need to rehone, then new pistons and rings would be needed also so I don't see how it saves anything more than the price of the block which is like 400 dollars. It took me two blocks and 90 dollar sonic tests for each to find a block to bore .060 safely. I had three cylinders offset bored by .020-.024. I would sonic test and offset bore even if I was only doing .030 over as some pin sides were only a little over .100 thick. That way wall thickness is maximized.
I think the theory is that if you junk a piston or two, score the walls, ect, but don't junk the block, then you can clean via a rehone or total .040 bore, replace the needed parts, and go back @ it.
What I'm saying is that you would need a bore and hone, new pistons and rings, bearings ect. The only thing I see you saving money on is the price of the block. You can't just swap one or two pistons and be done. You would also need to rebalance the rotating assembly for bigger pistons. What I saying is the amount of money you save would be negligable over using a new block and reusing the rotating assembly. I am yet to see a iron block forged motor take a crap anyhow.
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From: Hazard Co. Maryland
Originally Posted by strokedls1
What I'm saying is that you would need a bore and hone, new pistons and rings, bearings ect. The only thing I see you saving money on is the price of the block. You can't just swap one or two pistons and be done. You would also need to rebalance the rotating assembly for bigger pistons. What I saying is the amount of money you save would be negligable over using a new block and reusing the rotating assembly. I am yet to see a iron block forged motor take a crap anyhow.
No, that's what I was getting at too. I fully understand that to clean back up, you'd have to rebalance and buy new pistons. But still a few hundred bucks is a few hundred bucks, at least to me. To each there own there
On The Tree
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From: Colorado
I think I must be missing something....how much power do you expect to gain with the extra .020 or .030 bore? Unless it's an all out race only engine, is it worth sonic testing and sorting blocks for a minimal gain?
Not being critical, just don't understand.
Not being critical, just don't understand.
I went ahead and did the .060 because the person I get blocks from is local and willing to swap blocks until I had one that I liked. This may not be an option for most people. I paid a lot of money to build my engine how I wanted so I thought it was not a big deal to spend the money for a couple sonic tests. For many people it is much easier and safer to go .030 and be done with it.
Im going 4.060 with an offset grind on the crank to 3.70 making it a 383. All forged stuff and a really expensive *** heads and cam setup. 
Thanks guys for the input, but pistons are ordered and this motor is already half way down the track
Thanks guys for the input, but pistons are ordered and this motor is already half way down the track 
TECH Resident
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From: AUSTIN TX
Originally Posted by strokedls1
For the price of the block going under bore at .030 is just to be safe. If you have some issue where you need to rehone, then new pistons and rings would be needed also so I don't see how it saves anything more than the price of the block which is like 400 dollars. It took me two blocks and 90 dollar sonic tests for each to find a block to bore .060 safely. I had three cylinders offset bored by .020-.024. I would sonic test and offset bore even if I was only doing .030 over as some pin sides were only a little over .100 thick. That way wall thickness is maximized.
Now back to the topic, as far as going .060 just for the added 3-4 cubic inches over .030... It is not worth it. Test were done numerous years back on a regular production 350 block (left hand dipstick 2 pc rear seal, shows how long ago it was done) and on identical motors (may have even been the same motor built twice for the test) the .030 block made slightly more power in dyno test. It was concluded that the additional cylinder wall flex caused by the extra .030 removed on the .060 bore resulted in a decrease in ring seal that made a larger difference in performance than the extra displacement. Now granted the difference were negligable, and not enough to persuade someone to replace a block that needed to go .060, but it was enough to definately make you want to go .030 if possible.
I am not saying that everyone should do .060 over. An .030 over bore works just fine. The rods are centered on the crank. I assume you meant centered on the piston. I have floating pins on my pistons so I don't see it as an issue. I really doubt that such a small offset bore will make a difference at all in head flow. I understand all the dynamics of the machining process. I don't see how an sbc would compare in any way to a lqx block. What I meant by my last post is that if you replace the pistons and have to rebalance, bore and hone then you'll spend more money then just swapping blocks and reusing what you have. It is always better to start with a used block that has been heat cycled.