Plymouth 340 exhaust manifold to pipe Gasket

[tdwnilla1]

Hi everyone,

I am hoping to get a little help with an exhaust problem. I recently rebuilt my motor and would like to sort out my exhaust leak that I have had since I bought the car. I have always known of donut gaskets to be used between the pipe and the manifold however, when I purchased gaskets for my car the picture below is the only option I had. The other picture is what I have for clearance and as you can see the gasket I have would do no good. It is a stock exhaust on the car presently.

[autoxcuda]

72-73 340 has donut passenger exhaust manifold.

IiRC, it's like 1 7/8" dia. And IIRC, it's the same as a 71 360 C-body passenger ex manifold. And the E-body passenger head-pipe for it is the same as a 318.

Please confirm those thing though.


And it's much smaller than the 2 1/2" 68-70 340 hipo and some 71-74 A-body left side 340/360 manifolds.

Your headpipe looks like it's for a 70-71 flat gasket exhaust manifold. That's not going to seal properly to a donut exhaust manifold.

Also your heat stove valve is welded up and looks sort. Also... looks like some possible buggering near that weld.  Need more pics. Could be a past fixed crack. 

[autoxcuda]

Here pics of 72 340 Ebody exhaust manifolds

You need to identify exactly what castings numbers and configuration you have on each side and go from there. These cars get messed with heavily over the past 50 years.

[tdwnilla1]

Thank you for the reply Autoxcuda. I believe what you are seeing as a weld is the high heat paint that apparently was not high enough !! I will try to get some better pictures and post to this topic. It is a numbers matching car so very little has been messed with on the car but the pipe that attaches to the manifold does appear to have been welded and the manifolds appear to be stock.

[Tom Swope]

 The exhaust manifold pictured appears to be a 623 rs 340 exhaust manifold which does not require a gasket. This style is referred to as a ball joint metal to metal connection. It appears that your pipe  is an aftermarket or custom pipe with an incorrect flange. If the flange is incorrect maybe the pipe flare is also made incorrectly and is the culprit.  The heat riser is missing and possibly could be leaking from the modification made to where the flap shaft was originally installed. If you are definitely sure the leak is from this area check all of the above. Another possible issue is the manifold could be leaking from not having a flat surface to the head, having a crack or having corrosion pits.Hopefully the exhaust manifold was checked for these possible issues prior to installation as you mentioned having a problem previously.

[tdwnilla1]

 Thank you. I removed the heat riser assembly due to it not functioning anymore and I sealed the holes. Here are more pics

[Chryco Psycho]

  you have a cone style flange on the manifold & flat flange on the pipe / mismatched parts

[tdwnilla1]

Thank you Chryco, I sort of thought it was a 💩 show !! I dropped a ton of money into the motor and trans and want headers but need to hold off for a little bit and make this work for now. Chrysler had a lousy idea with metal to metal anyway so I think I am going to think outside the box on this one

[Chryco Psycho]

I actually prefer the cone , metal to metal over the gasket type flange