273 Exhaust manifold

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wheelsport

wheelsport

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I have had problems with the exhaust gaskets on my 273 sealing on each end of the manifold. The end ports' sealing surfaces are quite narrow, sometimes less than 1/8", which, combined with the narrow gasket surface, causes exhaust leaks. Has anyone come up with a solution?
 
With 340/360 heads, (and it's bigger ports) that can be an issue. With the stock 273/318 head, I've never had a problem with the stock exhaust manifold.
 
Yes,it sounds like a mismatch there. Post some photos
 
are you using the correct gaskets?

i literally just went thru this. early 318 and 273 gaskets are noticeably smaller in size and most places don't know or don't care and will sell ya the later 318/340/360 gasket.
 
Well they didn't come from the factory with gaskets, have tried it without gaskets?
 
Here's A picture of the stock gasket set. Note the surface width on the end gaskets. The surface on the head is ample but the end ports of the manifold are very narrow on the ends. Combined with the narrow gasket gives a very narrow seal. When installing the manifold, it's hard to position the gasket exactly in the correct location to prevent a leak. The only way to find out is to start the engine. If it leaks, you start all over. I took a little off the manifold, in an attempt to acquire a better seal but it's not enough. A fatter gasket would help.

1728413683293.png
 
Sometimes getting them rotated right can be the issue. The first set I change back in 2001, I had one of them upside down and it burned thru in a couple of weeks. Installed a new one rotated correctly and that 1/8, became the full surface match.
 
Does anyone have the correct part number for the smaller 273/318 gaskets?
 
i took a quick peek at remflex and didn't see that they had any with the correct dimensions. those would be my first choice if they have them.

here's a few other options:

www.summitracing.com

Mr. Gasket 7166MRG Mr. Gasket Header/Manifold Exhaust Gaskets | Summit Racing

Free Shipping - Mr. Gasket Header/Manifold Exhaust Gaskets with qualifying orders of $109. Shop Header and Exhaust Manifold Gaskets at Summit Racing.
www.summitracing.com www.summitracing.com

www.summitracing.com

Mr. Gasket 5938 Mr. Gasket Ultra-Seal Exhaust Gaskets | Summit Racing

Free Shipping - Mr. Gasket Ultra-Seal Exhaust Gaskets with qualifying orders of $109. Shop Header and Exhaust Manifold Gaskets at Summit Racing.
www.summitracing.com www.summitracing.com
 
HemiSSDart said:
Well they didn't come from the factory with gaskets, have tried it without gaskets?
Click to expand...
I will check, but i think my 273 Commando had a gasket in there with those big shields that keep the plug wires off the manifolds. I think it was just a steel shim, but still a gasket. In the attached photo you can see the driver's side guard/gasket between the manifold and plug wires and a matching left (passenger) side that has the gasket but no guard. As far as I know they are NOT reproduced. You can see it in red on the engine pic between the plugs and manifold. (Neither are my pics, but i confirmed that my 66 273 did have this set up when I took it apart.)

A-Body Heat Shield 273-318.jpg


engine 290.jpg
 
Absolutely correct. Here is the shield on a not as pretty original 273 Commando in my 65. Broken number 7 push rod and all.

IMG_0850.jpg
 
My 65, built in December '64 had the split set. The upper was on the car when dad bought it in '75.
20241008_150416.jpg

This set I pulled of a 66 formula S in the junkyard in 2003, had the over the hump.

Really have no idea what the actual difference in years and part numbers were.

When I worked at checker auto in 1990, they only had the over the hump version...
 
Yes the steel shim shield is what was used, there was no "gasket" though, context means everything...
 
HemiSSDart said:
Yes the steel shim shield is what was used, there was no "gasket" though, context means everything...
Click to expand...
So, is a steel shim head gasket "not-a-gasket" too? 'Cause my 66 273 Commando also had a steel shim that was embossed, much like the heat shield not-a-gasket, between the head and block when i took it apart.....for context.... .
 
Miranthis said:
I will check, but i think my 273 Commando had a gasket in there with those big shields that keep the plug wires off the manifolds. I think it was just a steel shim, but still a gasket. In the attached photo you can see the driver's side guard/gasket between the manifold and plug wires and a matching left (passenger) side that has the gasket but no guard. As far as I know they are NOT reproduced. You can see it in red on the engine pic between the plugs and manifold. (Neither are my pics, but i confirmed that my 66 273 did have this set up when I took it apart.)

View attachment 1716313281

View attachment 1716313282
Click to expand...
All 273s had a Chrysler or McCord thin metal gasket. It also prevented the ignition wires to get burnt.
 
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