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Hi all, I’m new to this forum and hoping someone can help.
Had a new transverse muffler installed on my manual ‘65 289C a few days ago and now the car stalls all the time, can’t keep it running I’m literally popping the clutch driving and my mechanic said maybe it’s the carburetor. Feels like there’s blockage somewhere or possibly carburetor issue but I can’t help but think it’s muffler related since it was running fine before I dropped it off. The muffler used to sit on the passenger side rear if I’m not mistaken flush with the undercarriage (from engine, pipe ran back to muffler and out see first pic). Now they did some weird loop that I’m def going to have them redo that you can see when driving behind it and it’s parallel to the gas tank but sideways see pics. Could this be creating a problem with air flow?

I’ve included before pics and then the after where you can see the new muffler, doesn’t look right.

this is the original...

746000


745997

745998

745999

You can now see the muffler when standing behind the vehicle which I hate. Please help.

746001
 

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can you feel decent exhaust flow from the pipe at idle? Stalls after warmed up, right away, or all the time? Restarts fine, then runs for how long?
 

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can you feel decent exhaust flow from the pipe at idle? Stalls after warmed up, right away, or all the time? Restarts fine, then runs for how long?
so once I start it up it runs with decent flow and then within a minute or two you can feel the engine start choking. I tap the gas peddle a few times rev her up to keep
It running and good for a minute and then it does again. Starts back up ok, might take me an extra crank or two to restart it but then repeat and it stalls. I drove it out of garage less then 1/4 mile and stalled 6 times had to Restart and drive it right home.
 

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Any chance you have a digital temperature gauge- the style you point at the object to check the temp?
 

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Any chance you have a digital temperature gauge- the style you point at the object to check the temp?
Unfortunately I don’t but I could probably get my hands on one, what should I check? Btw any chance you have a pic of the correct way a single transverse exhaust is supposed to be installed on a 65 289C convertible? Because this definitely doesn’t look like the way I dropped it off.
 

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Discussion Starter #7
Any chance you have a digital temperature gauge- the style you point at the object to check the temp?
I just realized my maintenance guy has one he checks the AC in the building with it, I could get my hands on it for sure in the AM
 

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The original muffler for a 65 or 66 with single exhaust was a transverse muffler, inlet and outlet on one side like that but they were kinda long (about as long as the gas tank is wide) and more flattened than oval, but it was barely visible if any from the rear. My car still had all the original on it when I got it, but I was young and too naive to realize I should save it when I installed a pair of duals and Thrush Cherry Bomb glass packs ...
It's possible, but not likely that the muffler you chose is too restrictive for the engine. It sounds to me like your choke is messed up.
 

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Discussion Starter #9
The original muffler for a 65 or 66 with single exhaust was a transverse muffler, inlet and outlet on one side like that but they were kinda long (about as long as the gas tank is wide) and more flattened than oval, but it was barely visible if any from the rear. My car still had all the original on it when I got it, but I was young and too naive to realize I should save it when I installed a pair of duals and Thrush Cherry Bomb glass packs ...
It's possible, but not likely that the muffler you chose is too restrictive for the engine. It sounds to me like your choke is messed up.
Thank you for the assistance I will for sure check the choke and the muffler was ordered to match what I have it’s just it doesn’t appear to be installed in the same place almost like they placed it vertical instead of flat with the undercarriage and I believe it used to sit on the passenger side near the rear tire and now it’s centered
By the gas tank and looks like crap from behind.
 

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Check the pipe temp before and after the muffler- see if there is a big difference in temp.
 

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If the muffler is actually plugged- it'll be considerably higher in temp at the inlet vs the outlet
 

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Another thing to check is to see if somehow the gas line exiting the gas tank has been smash or crimped. Since whoever put the muffler in was in that same area and all of a sudden it seems you're having fuel delivery/starvation issues....just a thought.
 

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If I were a guessing man..... wait, I AM a guessing man.... I'd say that, perhaps, he "tweaked" the rubber fuel hose and either pinched it, loosened it (so it's sucking air), cracked it (so it's sucking air) or in moving it around the inside, which frequently gets brittle, collapsed and is restricting flow. Guess number two is that the fuel hose is routed too close to the muffler and the heat is causing the fuel to boil in the line, forming a big air bubble.
 

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Discussion Starter #15
Another thing to check is to see if somehow the gas line exiting the gas tank has been smash or crimped. Since whoever put the muffler in was in that same area and all of a sudden it seems you're having fuel delivery/starvation issues....just a thought.
Good point, I’ll def check that as well. Did it make any sense for them to install the muffler where they placed it since it wasnt there to begin with and does it even matter other then aesthetics (I’m planning to move it where it originally sat either way just curious why they did that whole loop-d-loop).
 

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If I were a guessing man..... wait, I AM a guessing man.... I'd say that, perhaps, he "tweaked" the rubber fuel hose and either pinched it, loosened it (so it's sucking air), cracked it (so it's sucking air) or in moving it around the inside, which frequently gets brittle, collapsed and is restricting flow. Guess number two is that the fuel hose is routed too close to the muffler and the heat is causing the fuel to boil in the line, forming a big air bubble.
wow ok, that does sound possible as well and would certainly explain the issue im having. I just dint understand why these yo-yos moved the position of the muffler from where it originally sat to right behind almost touching the gas tank.
 

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Again, OE was a transverse muffler between the rear axle and the tank but that's hanging too low. The factory or dealer installed dual exhaust cars without GT trumpets also could have a transverse muffler there, but it had dual pipes to it, dual inlets and dual outlets. The loop is just how the inlet and outlet oppose each other without a crimp or too sharp of a turn. I installed duals on mine, and as do most, hung the oval mufflers close to the body in front of the axle and the tail pipes go over and out.
 

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Discussion Starter #18
Again, OE was a transverse muffler between the rear axle and the tank but that's hanging too low. The factory or dealer installed dual exhaust cars without GT trumpets also could have a transverse muffler there, but it had dual pipes to it, dual inlets and dual outlets. The loop is just how the inlet and outlet oppose each other without a crimp or too sharp of a turn. I installed duals on mine, and as do most, hung the oval mufflers close to the body in front of the axle and the tail pipes go over and out.
Ok thank you, so even though it doesn’t look similar to how I dropped it off you think it’s in the right position but just too low? Should it be flush with the undercarriage or on its side like that just higher? I’m going to call them today to ask them to fix it just want to be sure I tell them right.
Thanks for the follow up.
 

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For single exhaust, OE type, on its side like that just higher to clean up the installation and be sure the fuel line and hose aren't crimped.
 

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Check that rubber hose at the tank first.

If it is restriction in the muffler you can check it with a vacuum gauge hooked to intake manifold vacuum. Normally its used for checking for plugged catalytic converters which is real common. You never know a rat could have built a nest inside the muffler while it was on the shelf.

If you think the exhaust is plugged you can loosen the head pipe at the manifold and give it a leak and see if it runs.

I had phone company trucks that quit running way up in the mountains mile from the shop because of plugged catalytic converters. We tried to save money every way we could so they wouldn't outsource our jobs. I'd take a chisel and a hammer out to the truck and rip a hole in the catalytic converter. Start it right up and drive it back to the shop. It saved from having a large tow bill.


Exhaust back pressure test.

 
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