Red hot exhaust

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pgo
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Red hot exhaust

Post by pgo » Thu May 23, 2019 10:48 am

I own a 24 Fordor. I had the engine rebuilt 2 years ago and just installed it last week (health issues got in the way-mine not the car). The car starts and runs but the exhaust pipe turns cherry red quickly. I shut it down and looked up red exhaust here on the forum. I just did a compression test 42-45 pounds each cylinder EXCEPT #3. 20 pounds. Any thoughts? Thanks, I am new to this old technology.

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Mark Gregush
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Re: Red hot exhaust

Post by Mark Gregush » Thu May 23, 2019 10:55 am

Sounds to me like you are running too lean or timing. Open the spray needle a bit more and pull the spark lever down a bit more.
I know the voices aren't real but damn they have some good ideas! :shock:

1921 Huckster
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Erik Barrett
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Re: Red hot exhaust

Post by Erik Barrett » Thu May 23, 2019 12:00 pm

Running timing too retarded will get the manifold hot.


Norman Kling
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Re: Red hot exhaust

Post by Norman Kling » Thu May 23, 2019 12:07 pm

The low compression on #3 concerns me. First thing to check would be the torque of all head bolts. After the engine has been warmed up, you should torque the bolts to 50 ft lbs starting with the center and working side to side then next bolt to center and then side to side in each direction till you have 50 ft lbs evenly all around. See instructions on how to torque the head. Do it while hot if you have a cast iron head, and after it cools off again if the head is aluminum.

Then check the compression again. You can see down to the valves with a flashlight when the spark plug is out. Take a good look at #3 exhaust valve to be sure it is not sticking open. If it is stuck, you could very well be blowing unburnt fuel into the manifols where it will be burnt by the hot gasses from the other cylinders. That would cause the manifold to get hot.

Anyway, first check the torque. Then start it up again and try turning the fuel mixture a bit richer and the spark more advanced. If your problem persists, it could be a stuck valve or too little clearance on the valve. Low compression could also be caused by rings not yet seated. Running for a while and driving around would usually wear the rings in.
Norm

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Ruxstel24
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Re: Red hot exhaust

Post by Ruxstel24 » Thu May 23, 2019 12:32 pm

I would add to what Norm said...
After a re torque and valve inspection, do a wet compression test also.

Make sure your timer is moving with the spark lever, retarded timing will heat up the manifold, but usually not just idling. More so if driven this way.
Keep us posted... ;)

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TonyB
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Re: Red hot exhaust

Post by TonyB » Thu May 23, 2019 1:24 pm

Sorry to be the bearer of bad news but loss of compression in one cylinder usually indicates a valve problem. The red hot exhaust indicates incomplete or slow burning of the air/fuel mixture caused by low compression.
One test is to put the offending cylinder to TDC and blow in compressed air and see if it comes out of the carb (unlikely) or exhaust pipe (most likely).
Poor seating of rings is usually similar across all cylinders. Loss of compression on one cylinder is usually bad valves most often the exhaust valve.
While in there, I recommend you get rid of any two piece valves before they do it by themselves.
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1909 Touring, 1914 Touring, 1915 Speedster, 1924 Coupe.


Norman Kling
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Re: Red hot exhaust

Post by Norman Kling » Thu May 23, 2019 5:12 pm

If the problem is with a stuck valve, it is very possible that valve was open while the engine was stored for 2 years. Due to humidity, some rust might have been formed in the valve guide causing the valve to remain open. Sometimes it is possible to put some penetrating oil down the guide and allow it to set for a while then tap the valve down. If you do this tap right in the center so you won't bend the valve. Just tap lightly enough to move the valve. Then turn the crank over until the valve opens again and continue for about one turn of the crankshaft. See if the valve closes completely. If you are lucky you might not have to do a valve job, but if not, you will need to grind at least that valve and seat and set the proper clearance.
Norm


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Re: Red hot exhaust

Post by Stu Tomlinson » Thu May 23, 2019 9:05 pm

I agree with the valve problem for the one cylinder that has low compression, especially after a rebuild. I would recommend a leak down test for the cylinder in question. With this procedure you hook up compressed air - and it will quickly tell you if you have a leak through the intake or the exhaust. With the leak down test, a poorly seated intake will leak compressed air through the carb. For the exhaust, a poorly seated valve will pass air through the exhaust. then you know which valve to work on. I would almost guess that both these valves were not seated correctly during the rebuild.

Operating with a red hot manifold is not ideal as it will either warp it of break it. If you are going to run the motor with the car not moving, especially with a new motor, then remove the hood and place a box fan at the radiator to help move air. It is best to drive the car and keep it moving until the motor is properly broken in. Check the Tulsa T club web site for the proper way to break in a new motor.


DickC
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Re: Red hot exhaust

Post by DickC » Fri May 24, 2019 5:36 pm

Not to get something started but if the strong feeling is a stuck valve, (perhaps due to the storage) why not pore about one ounce of MMO into cylinder and let it sit for 48 hrs. Usually fixes the valve.


D Stroud
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Re: Red hot exhaust

Post by D Stroud » Sat May 25, 2019 5:47 am

Back in '91 or so when we first got the, TT, it had been setting for several years because of a bad rod bearing. After we got it home, my old buddy(RIP) came over. We replaced the rod cap(the babitt in the rod was OK) and started to check things out. Among a few other minor problems, three of the valves were stuck open. We squirted some penetrating oil on them from inside of the valve cover and through the spark plug holes. Tapped them down with a long screwdriver a few times while cranking it over with the hand crank. Fiddled with a few other things with fuel delivery and such and had it running in an hour and a half. We drove it around town for a few years after that. We did put some MMO in the tank "just because". This being said, sometimes a stuck valve isn't that much of a problem. These old T's are VERY forgiving, that's what made them so popular. While building them up like a Swiss watch is nice, it isn't always necessary. JMHO Dave
1925 mostly original coupe.


Dallas Landers
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Re: Red hot exhaust

Post by Dallas Landers » Sat May 25, 2019 8:08 pm

Dave, I dont know how long that TT set without being started at your place but I had that engine running in about a 1/2 hour. It ran good when I pulled it for a rebuilt engine install.


D Stroud
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Re: Red hot exhaust

Post by D Stroud » Sun May 26, 2019 6:59 am

Dallas, I don't recall starting it after 2009 when we got the coupe. Kind of landed on the back burner. :( Dave
1925 mostly original coupe.

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