Can anyone help explain why the exhaust manifold on my 1925 Model T is getting so hot it glows red after about 10 to 20 minutes of running. Or is this a normal occurrence?
It has had a conversion to a distributor instead of the trembler system.
Your spark is retarded too much.
Try adjusting the carburetor a little richer and see if that helps.
Yep, one or the other of the above, although I would lean toward retarded timing.
Normal don't worry. It is probably the most red at the connection to the tail pipe (it get very restricted there) assembly will often get red from #2 cyl all the way to the first bend in the exhaust pipe.
Ain't normal on either of mine.
Nor on mine. Either your timing is too retarded or your mixture is too lean or some of both.
Don't mean to be in any way sarcastic or anything, but Mike Robison is one of the Montana 500 guys and those guys push their "T's considerably harder than most of the rest of us do. I'm sure they notice red hot exhaust more frequently than a lot of the rest of us do,......so more "normal" for them than for a lot of the rest of us,......FWIW,......harold
What if it gets hotter at the first port? I've noticed discoloration on the metal (slight bit of grey change to silver in stripes) after car cooled down?
J W McCaughan......I had the EXACT problem on my 1925 Fordor back in July. I drove it and the exhaust pipe would turn Red Hot, about 3 to 5 inches, just below the Exhaust Pack Nut. it was a combination, be both, the Spark lever setting, AND being too Rich of adjustment in the carb,as a new T driver, I didn't know. Go to Google search.. and type in exactly: First Drive on Road, BUT..Exhaust pipe got RED HOT MTFCA
You will then read the whole discussion and suggestions, to clear it up. Good Luck
I had a red hot exhaust manifold one time years ago. The weather was below freezing and I had drained the cooling system. Got a call from a buddy in trouble so I took the T and went to help him. After pulling buddy out from a snowbank I decided to go and visit my oldest brother whose wife had just had their first child. Driving over there there was a funny smell coming from the engine and I wondered what it was. When I got to my brother's I opened the hood to see about the strange smell and there was this nice red hot exhaust manifold just sitting there as pretty as could be. That's when I realized that I had forgot to refill the cooling system. As near as I can figure I had driven about 8 miles w/out coolant.
After the engine had cooled down we refilled the system and I went home and never had any problems because of the overheating. Drove that T for about another 6 months after that.
Old practice back in the day with tune ups on
Detroit Diesels 71 series was to paint each
leg of the exhaust manifold. If the paint
darkened on each that was good. If one showed
good paint that cyl had a problem. I did this
when I did my rebuild and each paint mark aged
perfectly, if fact to this day you still can see
marks where the paint faded away. That not only
tells temperature, but tells healthy cylinders.
My theory is not proven, but I have always believed that a bad coil will let a raw gas mixture be exhausted into the manifold and that mixture will be ignited when the next cylinder fires, which will make a red hot spot in the manifold.
I have seen manifolds that were only red hot in small areas and it was not always the same area.
If that still occurs with a distributor that provides 4 good sparks through 4 good wires to 4 good spark plugs, then my theory is wrong.
If the muffler is plugged with debris, the hot gasses would linger longer and that may cause them to impart more heat to the exhaust pipe.
Then a few years ago, I told a guy that his Toyota engine should start if it had gas and a good spark at the right time. That was not true though, as his muffler was plugged and the engine could not breath at all.
I do know that a retarded spark will cause extra heat in the manifold.
I do know that it it a little trickier to properly set the timing with a distributor.
I do know that most distributors have built in counter-weights that advance the spark at higher speeds and the spark lever can normally only be pulled half way down for optimum operation, especially if you are using a Bosch VW 009 distributor.
In my car racing days it always meant that the carb mixture was way to lean
Sorry for the delay in reply - on Holiday!
Thank you everyone for the friendly support. As a new person to Model T ownership it is great to know there are so many people around the world ready to help.
I will try the timing and mixture adjustment this weekend and report back next week with the results.
A rich mixture will not cause a red-hot exhaust manifold. Just the opposite is true.
Too rich runs cooler. Too lean runs hotter. If you are too lean, and the manifold is turning red because of it? You will burn the exhaust valves if you run that way long enough.
Another thing that will sometimes turn the manifold red is dwell time on the flow of hot gasses. If you are running and pulling hard, you are burning more fuel, which then runs hotter. If that hard run is fairly slow rpm, the burning gasses hang around longer inside the manifold and transfer more of their heat to that manifold. Dwell time will also affect the valves, but long dwell also means longer sitting closed which offsets the heating of the valves some (hot valve heads sitting on somewhat cooler block is what helps cool the exhaust valves).
If your manifold is glowing red? Consider what kind of driving you have been doing? But running slightly lean helps your exhaust valves last longer.
Drive carefully, and enjoy, W2