69 Big Block Intake Gasket

[Al M.]

My 1969 L68 coupe has been in storage for several years and I'm looking to get running again. My question relates to the intake manifold gasket which had been removed at the start of storage and now I'm reinstalling it. The gasket that was on the car was black in color and part of it was exposed from the exhaust cross over to the number 3 intake runner on the left side and the cross over to the number 6 runner on the right. There was no embossed "GM" or part number visible on either side. While I don't believe this was the original gasket, my question is, is black the correct color for the gasket? I purchased a gasket set from Paragon a few years back thinking it was a (somewhat) correct repro, but what arrived was gray in color and no "GM" stamping followed by a part number. I also understand that there was some over spray on the gasket, but how much? Was the gasket completely covered?

Since original gaskets are near impossible to find and tend to leak, I would prefer reproductions that at least resemble the originals and cost too many points. I don't want to install these and then have to replace them later. I would much rather buy another set if these aren't acceptable replacements. I've attached photos of both.

[Joe L.]

Re: 69 Big Block Intake Gasket

My 1969 L68 coupe has been in storage for several years and I'm looking to get running again. My question relates to the intake manifold gasket which had been removed at the start of storage and now I'm reinstalling it. The gasket that was on the car was black in color and part of it was exposed from the exhaust cross over to the number 3 intake runner on the left side and the cross over to the number 6 runner on the right. There was no embossed "GM" or part number visible on either side. While I don't believe this was the original gasket, my question is, is black the correct color for the gasket? I purchased a gasket set from Paragon a few years back thinking it was a (somewhat) correct repro, but what arrived was gray in color and no "GM" stamping followed by a part number. I also understand that there was some over spray on the gasket, but how much? Was the gasket completely covered?

Since original gaskets are near impossible to find and tend to leak, I would prefer reproductions that at least resemble the originals and cost too many points. I don't want to install these and then have to replace them later. I would much rather buy another set if these aren't acceptable replacements. I've attached photos of both.

Al-----

Although this gasket set is 100% FUNCTIONALLY correct, it is not CONFIGURATIONALLY correct for a 1969 L36/L-68. The original gasket set was GM #3955526. It was a medium gray in color and its perimeter configuration was somewhat different than the gasket set shown. Although most of the gaskets cannot be seen when installed on the engine, enough can be seen to discern the pictured set from the original.

Another very small point: original GM gasket sets have "GM" embossed on the tabs of the end seals. I understand that this is a feature which judges look for. No reproduction set I know of has this feature.

The gaskets pictured are, however, of the embossed type as were the original gaskets. I consider this to be the best type for sealing. Many current gasket sets on the market are not of the embossed type.

[Terry M.]

Re: 69 Big Block Intake Gasket

My 1969 L68 coupe has been in storage for several years and I'm looking to get running again. My question relates to the intake manifold gasket which had been removed at the start of storage and now I'm reinstalling it. The gasket that was on the car was black in color and part of it was exposed from the exhaust cross over to the number 3 intake runner on the left side and the cross over to the number 6 runner on the right. There was no embossed "GM" or part number visible on either side. While I don't believe this was the original gasket, my question is, is black the correct color for the gasket? I purchased a gasket set from Paragon a few years back thinking it was a (somewhat) correct repro, but what arrived was gray in color and no "GM" stamping followed by a part number. I also understand that there was some over spray on the gasket, but how much? Was the gasket completely covered?

Since original gaskets are near impossible to find and tend to leak, I would prefer reproductions that at least resemble the originals and cost too many points. I don't want to install these and then have to replace them later. I would much rather buy another set if these aren't acceptable replacements. I've attached photos of both.

Look on eBay. I was able to find an NOS square port intake gasket set in six months (and no, it was not inexpensive), and I suspect if you look long enough a round port set will show up. Good reproductions of square port gaskets are available there also, but I haven't yet seen a reproduction round port set. Patience and time are the key.

[Stephen L.]

Re: 69 Big Block Intake Gasket

Al, I used a set of gaskets like you have and cut them to match the photo in my Service Manual. I've passed numerous judgings. I did this on a 67 390 L36.

Some folks say the gasket should follow the manifold foot print, (the trimmed black gasket in the photo). This is NOT correct.

The gasket will be "painted" when installed as there is some "paint" along the edge of the aluminum manifold in this area. On a L36 the engine and manifold are completely "painted"

[Patrick H.]

Re: 69 Big Block Intake Gasket

Al, I used a set of gaskets like you have and cut them to match the photo in my Service Manual. I've passed numerous judgings. I did this on a 67 390 L36.

Some folks say the gasket should follow the manifold foot print, (the trimmed black gasket in the photo). This is NOT correct.

The gasket will be "painted" when installed as there is some "paint" along the edge of the aluminum manifold in this area. On a L36 the engine and manifold are completely "painted"

Nice job.

What did you use to cut the gaskets?

[Stephen L.]

Re: 69 Big Block Intake Gasket

Patrick, It's been a long time ago that I cut them. I think I used some tin snips......

[Patrick H.]

Re: 69 Big Block Intake Gasket

I've tried before and the edge usually looks ragged, that's why I ask.

[Joe L.]

Re: 69 Big Block Intake Gasket

I've tried before and the edge usually looks ragged, that's why I ask.

Patrick------


What you describe is exactly what I would expect with this type of gasket.

[Al M.]

Re: 69 Big Block Intake Gasket

Stephen, Do you think a utility (sheetrock) knife with a new blade would work? I'm not sure as the gaskets may be too thick for it. Also I thought snips would leave an uneven edge, but yours look really smooth.

[Joe L.]

Re: 69 Big Block Intake Gasket

Stephen, Do you think a utility (sheetrock) knife with a new blade would work? I'm not sure as the gaskets may be too thick for it. Also I thought snips would leave an uneven edge, but yours look really smooth.

Al------


These gaskets have a thin steel core. That's what makes them difficult to trim.

[Jimmy G.]

Re: 69 Big Block Intake Gasket

Round port side gaskets are not difficult to find. I have 30 sets or so (and unlike parts from Joe L. - They can be bought). They work well even being 50 years old. Cork original valve cover gaskets -- NOT SO GOOD

[Stephen L.]

Re: 69 Big Block Intake Gasket

Snips I used...... straight cut

https://www.harborfreight.com/hand-tools/saws-cutting-tools/snips/straight-cut-aviation-snips-39611.html

[Joe L.]

Re: 69 Big Block Intake Gasket

Al-------


Below are photos of the "GM" embossment on the big block end seals. These are found on GM gaskets but not aftermarket or any reproduction I'm aware of. I consider these to be insignificant because they represent only a "virtually microscopic" element of configuration. However, some judges do not share my opinion. So, I present them here for edification purposes only.

[Al M.]

Re: 69 Big Block Intake Gasket

Thanks very much Joe. I appreciate the info.

[Chris H.]

Re: 69 Big Block Intake Gasket

I’m disassembling my ‘69 L71. Here are photos of the intake gaskets front and rear.