L79- Which Head Gasket?

[James B.]

I am restoring my very original '67 L79 coupe and intend to have it judged (at least up through a regional). I have the engine off the chassis and at the rebuilder's shop. I have been very careful to tell him not to deck the block. I am now debating whether to go back with an original thickness steel head gasket or a FelPro composite. When the block is cleaned I will take a look at it with the rebuilder and see if he thinks the surface is good enough to seal with steel. I would like to use steel partially because I do not want to reduce compression (I am going back with the original 11:1 CR) but more importantly I don't want the judging deduct.
Can anyone tell me what the judging point hit is likely to be if I need to go with a composite gasket? Has anyone recently done a steel gasket on an original, undecked block and if so did it seal okay?

[Duke W.]

Re: L79- Which Head Gasket?

The original gasket was .018", but I'm not aware that a exact thickness gasket is offered today. Felpro offers a .015" and I think the next up is in the low twenties.

You should have asked for advice before the engine was disassembled. Deck clearance should be measured prior to block disassembly to get a handle on compression ratio. Then you measured head chamber volume, and along with piston volume use different gasket thicknesses to establish your maximum target CR using an online CR calculator, which I recommend at about 10.3 maximum.

Also, your connecting rods are iffy, and you should consider replacing them with stronger aftermarket offerings.

I suggest you suspend further work until you understand the issues and have a good plan including a manufacturer/part number for every part that MIGHT need to be replaced. Don't worry, the list won't be very long.

I've helped many with system engineering engine restoration issues, so feel free to contact me via the email link on the TDB. We can get hooked up on the phone, and I can send you some useful documents on Corvette engine restoration. The archives are full of disasters because owners let machine shops and mechanics do it "their way". Don't add yourself to the victim list.

Duke

[Donald O.]

Re: L79- Which Head Gasket?

My 67 L79, before I gave it a valve job 25 years ago, had the tin metal shim style gasket that GM used. If have the engine rebuilt this spring/summer, I will use the same style gasket. Torqued properly and to the correct value didn't leak then and won't leak now.

Nay-sayers flame on.

DonO

[James B.]

Re: L79- Which Head Gasket?

Duke and Don, thanks for your responses and input. Duke, I've sent you a private message.
Jim B