Bare Block Bore

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May 14, 2008 | 12:38 PM

OldSchoolSS

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Staging Lane

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Bare Block Bore

Hey guys,

What is the cylinder bore on a brand new LS2 block from GM? Do I have to get it bored or honed before I build a 402 stroker motor?

Thanks,

OSSS

May 14, 2008 | 01:05 PM

Sharpe

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From: Southeastern IL

Dont feel like looking up the answer to your first question (Google), but you do have to bore slightly to get to 402". Of corse, you'll need the stroker crank too. Just look at rebuilt kits in Jegs or something.

May 14, 2008 | 01:14 PM

z34_nut

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From: NorCal

You should go to 4.005 if you decide to build a stroker engine. If you are able to find a good machine shop, they will put a torque plate on your engine and make the bore 100% concentric to your new pistons after mic'ing them.

This will help reduce oil consumption.

May 14, 2008 | 03:14 PM

OldSchoolSS

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Staging Lane

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Thanks for the replies guys, I did some searches but all I could find was a rough dimension of 4". I wasn't sure if the blocks came prehoned from the factory for a certain size piston.

May 14, 2008 | 03:58 PM

z34_nut

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From: NorCal

They do come finish honed, but for a stroker application, I do not trust it. The right way to build it is to have each block machined to each piston.

May 14, 2008 | 07:51 PM

bifster

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From: cobourg ON

why are guys using the ls2 blocks and the l92 blocks instead of the lsx block? its much stronger and most likely cappable of handeling more power .? just curiouse

May 14, 2008 | 08:56 PM

67SS509

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From: Whiteville, NC

Quote:

Originally Posted by OldSchoolSS

Hey guys,

What is the cylinder bore on a brand new LS2 block from GM? Do I have to get it bored or honed before I build a 402 stroker motor?

Thanks,

OSSS

I have built several using the block just like it came from GM. I checked the bores on everyone with a bore gauge that had .0001" accrucy. The most I have found one off was .0002" under the 4.00" and were good from top to bottom. I have found some iron blocks .0004" under. Their hone is as good as you get also. But do have it checked and check your pistons also. I ran across a new set of forged pistons recently that had one way off on diameter.

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May 17, 2008 | 08:13 AM

KCS

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From: Conroe, TX

Quote:

Originally Posted by OldSchoolSS

Hey guys,

What is the cylinder bore on a brand new LS2 block from GM? Do I have to get it bored or honed before I build a 402 stroker motor?

Thanks,

OSSS

Yeah, usually you are gonna want to hone it. That way the machinist can set the piston-wall clearance for the piston's ACTUAL diameter, and if they're good, use a sequence of stones to give it a nice surface finish for better wear/friction/oil control characteristics.

Boring is usually reserved for taking out alot of material, as in going from a 4" bore to a 4.030" bore. Honing will take care of a few thou.

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May 17, 2008 | 08:16 AM

KCS

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From: Conroe, TX

Quote:

Originally Posted by bifster

why are guys using the ls2 blocks and the l92 blocks instead of the lsx block? its much stronger and most likely cappable of handeling more power .? just curiouse

A lot of times, an LSX is overkill. A lot of times, you can get an aluminum block for less than half the cost of an LSX before machining. A lot of times, people just want the weight difference of aluminum. It's personal preference.

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