Head Gasket Thickness for 1969 L-78 (375hp/396)???

**KnoxvillePig** · #1 07-17-2006, 09:14 PM

O.K. I need all you motor heads to step up. I am currently ordering parts in order to put the engine for my 1969 L-78 Camaro back together. What is the correct stock thickness for 1969 L-78 (375hp/396) head gaskets in order to run stock 11:01 compression? What brand/company would you recommend for correct appearance? Any suggestions would be appreciated. Thanks Guys.

Darrell

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1969 RS/SS L-78 Camaro

**k92** · #2 07-17-2006, 11:20 PM

I don't know the correct gasket for your car, it will depend on the tolerences that your builder comes up with. Don't expect to get the factory advertised comp ratio without some work. On my ls6 it came out to be 10.86 to 1 after blue printing it. The deck was untouched.honed 10 over with venolia pistons,heads milled and no massaging of the combustion chamber, Obviously if it was not honed larger and the heads not milled it would have been even lower so the factory numbers aren't exact.

**JRSully** · #3 07-18-2006, 05:38 AM

as mentioned above, if you have either the block decked and/or the heads milled or cc'd your engine builder may need a thicker head gasket to "come down to" 11:1 since the combustion chamber in the head may be smaller due to the milling and that would INCREASE compression with a stock 11:1 piston and stock gasket

**KnoxvillePig** · #4 07-18-2006, 08:56 AM

I didn't even think about the heads coming into play. I am glad you brought that to my attention because I haven't even taken them to be checked yet. Hopefully they will not need to be milled. I will wait until my heads are ready and check w/ my builder.
I wonder if the local GM dealer still offers original style head gaskets?
Thanks guys for your comments

Darrell

budnate · #5 07-18-2006, 07:00 PM

after you get the shortblock together you can measue where your at and then CC the heads...there is head gasket Co. that will make them any thicknes you need to land at the best quench, there about 150 a set, do a search under Quench on Team Camaro we hashed this out many times over the last two years some real good reading I might add

**Salvatore** · #6 07-18-2006, 11:09 PM

Felpro is a good gasket. They have it for your application.

**scuncio** · #7 07-19-2006, 12:32 AM

The Felpro multilayer coated gaskets (standard blue ones) are typically around 0.041" compressed thickness. If memory serves me right the original steel shim gaskets are closer to 0.019" compressed thickness. Combine that with the typical 0.015" piston depth below the deck (assuming a factory piston and a factory deck surface), it's almost guaranteed that you'll have a lower CR than advertised. For example, my stock 1970 LS5 ended up being around 9.75:1 with the 0.041" Felpro gasket and stock pistons that were 0.016" below the deck. Just my experience.

**Salvatore** · #8 07-19-2006, 01:37 AM

Sounds about right. We used the Felpros. My 69 302 came out to be around 10.55:1. Had to fly cut the TRW's. I think the tin original head gaskets are 0.017 or 0.019, Like you said. Worked out fine.

**k92** · #9 07-19-2006, 06:21 AM

My ls6's compression ratio came out to be 10.86, each combustion chamber was just under the factory advertised 108 cc's, like 107.8 I think. So it's real doubtful that it ever came with the factory 11-1.

**KnoxvillePig** · #10 07-19-2006, 08:48 AM

I really want to thank everyone for your help and please forgive my ignorance on the subject. As you probably already figured, this is my first experience w/ engine building and it sounds like I am already putting the cart before the horse so to speak.

I was just trying to go down my list and round up all misc. items so everything will be ready for my builder.

I was apparently under the misconception that if I ordered everything at factory specs, I would achieve the factory 11:01 Comp Ratio I am looking for. I didn't even take into account the possibility that my heads may need some milling and/or the TRW pistons I ordered may have slight differences in the dome from factory originals which may create a slightly different "in the hole" measurement (Just learned that after searching the word "Quench" on Camaros.net.....Thanks budnate)

I guess it just makes sense to assemble the shortblock first, get my heads ready and then let my builder decide which head gaskets I will need to get as close to 11:01 CR as I can.

Thanks to everyone again for enlightening me on a few things
This site is certainly a God Send for some of us
This will obviously be a learning experience for me.

Darrell

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