1972 L48 Head Gasket - Recommendation Sought!

[Don L.]

Hi all.

I searched archives and found numerous threads on this subject, however, I didn't see one that was specific to my need.

I have my cylinder heads off for valve work this winter and am hoping I can get a great recommendation for which type and which brand head gasket to use when reassembling. I've heard people talk about using a metal-only gasket for a slight increase in compression. Meh. I removed composite gaskets, which never gave me trouble.

What's my best choice, guys?

Thanks in advance for your advice.

[Edward J.]

Re: 1972 L48 Head Gasket - Recommendation Sought!

Hi all.

I searched archives and found numerous threads on this subject, however, I didn't see one that was specific to my need.

I have my cylinder heads off for valve work this winter and am hoping I can get a great recommendation for which type and which brand head gasket to use when reassembling. I've heard people talk about using a metal-only gasket for a slight increase in compression. Meh. I removed composite gaskets, which never gave me trouble.

What's my best choice, guys?

Thanks in advance for your advice.

Don, sometimes you can get a OE head set on line like Ebay motors, that would be my first preference and then Fel Pro If you dealing with a block or head that may not be quite flat, Fel Pro is a little more forgiving.

[Joe R.]

Re: 1972 L48 Head Gasket - Recommendation Sought!

Don,

Only Fel Pro would I consider.

JR

[Patrick H.]

Re: 1972 L48 Head Gasket - Recommendation Sought!

Fel-Pro 1003. Just used them a week ago on an LT-1. Jegs/Summit sell them cheapest, but note they come 1 per package.

[Duke W.]

Re: 1972 L48 Head Gasket - Recommendation Sought!

The advertised CR of your engine is 8.5:1 with the OE .018" shim gasket in order to operate on unleaded 91 RON (equivalent to today's 87 PON) fuel, but may be lower depending on deck clearance, which I recommend you measure.

As long as the deck and head mating surfaces measure flat with a machinists bar and .0015" feeler gage I recommend using a steel shim gasket, and the thinnest I know of is the Fel-Pro 1094 at .015". I has a polymer coated surface to aid sealing, and this gasket should allow the engine to continue to operate detonation-free on 87 PON fuel.

Patrick - what's the thickness of the 1003?

Duke

[Don L.]

Re: 1972 L48 Head Gasket - Recommendation Sought!

Thanks guys. Much appreciated.

I suppose I can't really say whether or not my cylinder heads are exactly flat of not, but I've never had a leak problem and when I removed them, I did see broach marks, indicating to me that they have not been faced. The block shows same. I should note that a previous owner had the engine redone (1991), therefore, the composite gaskets that I removed must be replacements. Someone suggested I consider using a steel gasket in an effort to gain (minimal) compression. Seems this group feels the composite gasket is a better choice, therefore, I'll move that way. I'll look toward the Fel-Pro 1003 as suggested.

On another note, I see some posts suggesting against the use of standard rubber gaskets at the front and rear of the intake when re-assembling. A liberal bead of RTV was recommended instead. My builder is expecting to take approx. 0.010" off the face of each head. This, of course, will lower the interface at the intake manifold. Does that matter at all in choosing intake to head gaskets? Rubber (front and rear) gaskets? Thoughts?

Thanks again...

Don

[Don L.]

Re: 1972 L48 Head Gasket - Recommendation Sought!

Thanks for jumping in Duke. I had typed my last post before you posted, but hit SEND after you posted. I appreciate the counter-point. I have confidence in the engine builder and I will ask that he ensure flatness as you suggest. I look forward to hearing about the Fel-Pro 1003 gasket thickness.

[Patrick H.]

Re: 1972 L48 Head Gasket - Recommendation Sought!

You guys forgot how to use Google?

https://www.summitracing.com/parts/fel-1003

[Don L.]

Re: 1972 L48 Head Gasket - Recommendation Sought!

Hah! Google schmoogle. I read it on the internet, therefore, it MUST be true...

Thanks Patrick. There's quite a difference in thickness. I wonder what a 0.025" or so thickness difference might do for compression, especially when taking approx. 0.010" off the face of the cylinder head for truing?

Also, is a steel-only gasket more prone to leak problems?

[Edward J.]

Re: 1972 L48 Head Gasket - Recommendation Sought!

Don, this would be a wise to use a sealant, I like Permatex Right Stuff been using it for years and seals like no other, and is black which kinda, sorta looks like a gasket. once it dry(24hrs) take a razor blade and trim of excess.

[Don L.]

Re: 1972 L48 Head Gasket - Recommendation Sought!

Thanks Ed. I looked it up. Looks good. I think I'll go with this instead of the formed rubber gasket. The spec sheet doesn't say whether or not it's paintable. do you know?

[Duke W.]

Re: 1972 L48 Head Gasket - Recommendation Sought!

Hah! Google schmoogle. I read it on the internet, therefore, it MUST be true...

Thanks Patrick. There's quite a difference in thickness. I wonder what a 0.025" or so thickness difference might do for compression, especially when taking approx. 0.010" off the face of the cylinder head for truing?

Also, is a steel-only gasket more prone to leak problems?

Simple. Use a compression ratio calculator. You can do a web search for a paper I co-authored that was published in both The Corvette Restorer and a couple of chapter newsletters on how to "manage compression ratio", but I can tell you off the top of my head that, all other things equal, a .025" gasket thickness increase will knock the CR down about half a point.

As long as the heads and block deck are level as I explained before, a shim gasket should seal. The trouble is, most machine shops don't bother to make this simple measurement. They just go ahead and cut metal. That's why I recommend that you closely supervise the machine shop on exactly what operations they perform.

My first rule of engine restoration is: only cut metal if absolutely necessary.

Duke