My engine builder spec'd out and shipped GM part number 12610046 for my L92 based 427 (or 429 if you do the math). The stock bore is 4.065" on those blocks, but this was bored out to 4.080" according to the spec sheet. Will those gaskets still work? My gut feeling is telling me that it's going to overlap into the cylinder to the tune of a .0075" lip all the way around...

 

The gasket is chosen for the wider of the two which is in this case a 4.085". Cometic has this size. I used the 4.085 on my car. As far as the cylinder head bore, yes it will be smaller than the cylinder block bore but so was every 243 headed LS2 with a 4" bore and a head designed for a 3.9" 5.7 liter. Nothing new or bad about it.

The use of the stock gasket is what has me puzzled. If you didnt go ahead with the work with this builder, I would like to point out that Lingenfelter sells a forged 427 with a LS7 block that sells for $6200-6400 complete and with no core. They also know what they're doing and dont have customers searching for what head gaskets work with the set-up. What is the recomendation of the engine builder? Are you just double checking his opinion? If youre happy with the work and he has done this before then all is fine. I personally dont think the liners are a good candidate for being bored to anything more than a clean-up hone.

Texas speed and Scoggins Dickey both sell a 427 for under 6K with a LS7 block. Why not use a 4.125" bore? I hope you're saving enough to warrant this move to a thin walled/bored LS3 block. For what its worth they also sell 416 L92 strokers for 4700 or so complete with no core.

They have them in stock and there are enough feedback customers to tell you what works and doesnt work with the set-ups.

 

It's too late to go back now, though if I had it all to do over again... but that's another story entirely.

The original project started out as a heads/cam swap on the stock LS2 but turned into an entire engine replacement. The heads are PRC L92's, block is the L92 as mentioned. All parts sourced from the same vendor/builder. During a final parts tally I asked for head-gaskets, they said OK. Those are the gaskets I got, so I assumed they would be ok.. now I'm not so sure.

 

Info from GM Performance Catalog.
L92/LS3 Head Gasket:

 

awesome. I was searching everywhere for that info last night and google failed me

Appreciate the reserch!

 

Do you have a link to that? I looked up those 12610046 and couldn't find them in the gmperformanceparts site, and sdparts has them listed as a 4.065" bore. Not that I don't believe you, I just want to see it so I feel better

 

Its on the NEW GM Performance Parts Catalog. No link....
I am looking right at it. I can post a pic with my camera phone tomorrow if you want.

 

Nah, that's fine. Again, I appreciate it.

I just wanted to make sure it was safe to run it and drive it. Still plan to replace them with something a bit better. I assembled the engine (put the heads on) with the gaskets I was sold. I'm pretty savvy when it comes to assembling and troubleshooting, but I'm no engine builder. I don't spec things out, I don't want to do the math. That's why I paid good money for a reputable shop to do it for me...