Glowing in the gloaming (exhaust manifold temp)

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Model T Ford Forum: Forum 2012: Glowing in the gloaming (exhaust manifold temp)
Top of pagePrevious messageNext messageBottom of page Link to this message  By Chris Bartol on Friday, May 25, 2012 - 10:44 am:

I had to do some work on the '26 tourer yesterday. I thought I had blown a head gasket, but it turns out that for some reason, one of the new valve spring cup retainer pins has sheared (new stainless valves installed by me about 2 or 3 years ago). I put in a replacement pin and redid the head gasket and started him up. The head was smoking a bit due the use of Indian Head gasket shellac heating up, but then I noticed that since it was the gloaming (aka, dusk), I could see that the exhaust manifold was starting to glow cherry red in front of port # 3 (# 1 being the front cylinder). Is this normal or is there something going on here? Keep in mind, the radiator was full after having been drained, but perhaps the thermo-puke cooling system hadn't kicked in yet, either (no water pump on this one). Any thoughts or concerns? It sounded fine and ran fine. Thanks, Chris the clock man


Top of pagePrevious messageNext messageBottom of page Link to this message  By Henry Petrino in Modesto, CA on Friday, May 25, 2012 - 10:52 am:

My amateur opinion is that a red glowing exhaust manifold indicates it's running a little lean.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Ricks - Surf City on Friday, May 25, 2012 - 11:16 am:

Spark retarded.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Dick Lodge - St Louis MO on Friday, May 25, 2012 - 11:18 am:

Ralph, please be more careful with your language. The spark is developmentally challenged....


Top of pagePrevious messageNext messageBottom of page Link to this message  By Ricks - Surf City on Friday, May 25, 2012 - 11:22 am:

Sorry, Dick, you see I'm retar'd. Been retar'd 12 years now. Dunno how I ever found time to work..

The spark is late to the party?

rdr


Top of pagePrevious messageNext messageBottom of page Link to this message  By Henry Petrino in Modesto, CA on Friday, May 25, 2012 - 11:36 am:

It sure could be that the spark is arriving a little late. I've experienced that problem. What I don't get is how come late spark makes it run hotter than spark that's on time?


Top of pagePrevious messageNext messageBottom of page Link to this message  By John Semprez-Templeton, CA on Friday, May 25, 2012 - 12:01 pm:

It could be the engine is running a bit lean. You may want the mixture to become slightly more obese (or wealthy).


Top of pagePrevious messageNext messageBottom of page Link to this message  By Chris Bartol on Friday, May 25, 2012 - 12:07 pm:

This email just came to me today. It seems really appropriate for our off-topic fun!

"RETARDED" GRANDPARENTS


Written by a third grader , on what his grandparents do.

After Christmas , a teacher asked her young pupils how they spent their holiday away from school. One child wrote the following:

We always used to spend the holidays with Grandma and Grandpa. They used to live in a big brick house , but Grandpa got retarded and they moved to Florida. Now they live in a tin box that has wheels, but its strapped to the ground. They ride around on their bicycles , and wear name tags , because they don't know who they are anymore. They go to a building called a wreck center, but they must have got it fixed because it is all okay now, they do exercises there , but they don't do them very well. There is a swimming pool too, but they all just jump up and down in it with hats on. At their gate, there is a doll house with a little old man sitting in it. He watches all day so nobody can escape. Sometimes they sneak out, and go cruising in their golf carts. Nobody there cooks, they just eat out. And, they eat the same thing every night - early birds. Some of the people can't get out past the man in the doll house. The ones who do get out, bring food back to the wrecked center for pot luck. My Grandma says that Grandpa worked all his life to earn his retardment and , says I should work hard so I can be retarded someday too. When I earn my retardment, I want to be the man in the doll house. Then I will let people out, so they can visit their grandchildren.


Top of pagePrevious messageNext messageBottom of page Link to this message  By James A. Golden on Friday, May 25, 2012 - 12:11 pm:

I have always had an unproven theory that if the exhaust glows in just one area, it was because the cylinder did not fire and the raw gas charge was dumped into the exhaust manifold and ignited by hot gas from the next cylinder to fire.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Hal Davis-SE Georgia on Friday, May 25, 2012 - 12:16 pm:

A late spark means a late burn. The expanding gases are too late to push the piston down like they are supposed to and they are still burning as the exhaust valve opens. This is the reason for lack of power and the glowing exhaust manifold when running with 'insufficient advance.' Is that PC enough for you guys?:-)


Top of pagePrevious messageNext messageBottom of page Link to this message  By Henry Petrino in Modesto, CA on Friday, May 25, 2012 - 12:20 pm:

Thanks, Hal. I guess I never thought it through as you explained it. And yes, your post is PC. However, being PC doesn't usually get you much on this forum! :-)


Top of pagePrevious messageNext messageBottom of page Link to this message  By Vince M on Friday, May 25, 2012 - 12:27 pm:

If an engine is running lean, should it stop running and maybe have a sandwich?

Vince


Top of pagePrevious messageNext messageBottom of page Link to this message  By Ricks - Surf City on Friday, May 25, 2012 - 01:12 pm:

It was fun to retard the spark at night when the Fronty had 3 short straight stacks. It would shoot blue flames two feet out and make a good roar.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Wayne Sheldon, Grass Valley, CA on Friday, May 25, 2012 - 06:55 pm:

Two things.
1. Due to the firing order and manifold on a model T, The manifold gets hottest at the number three exhaust port. Think about it. 1 fires, the exhaust heads out just as 2 fires. As the exhaust heads out from two, hot on the heals of 1's exhaust, number 4 fires. It is the furthest back, numbers 1&2 have not completely left the manifold. 4's exhaust hits the back pressure and backs into number 3's exit just as 3 tries to head out. Number 4 doesn't get as hot because the combined push of 1,2 & 4 have pushed the speed up to the fast track out the tail pipe. Number 3 gets hotter because it exits into the back-pushed number 4 and has to get it's speed up on it's own while the furthest away number 1 is getting ready to go join it. The cycles repeat, always with a slight delay on number 3's exit. That delay is known as dwell time, and allows more heat transfer to the manifold at that point.
I figured this out about forty years ago after noticing several Ts on a tour all had glowing on number 3 manifolds. It was a fun exercise in the eddies and currents of fluid dynamics. RPM, throttle settings, and torque all have effects on the timing and flow.

2. Another consideration. Both fuel mixture and spark timing do have a major effect on the temperature of the gasses leaving the cylinder.
If the timer is not properly centered on the cam shaft through proper centering of the front cover or other issues, the spark will end up earlier on one or some cylinders than another one or some.
New Day, and other front brush type timers are affected less by this than most other timers including the most common roller type timers. Picture the roller, on a lever, working on a fulcrum off to one side. If the space between the camshaft and the track around it is not perfectly even, the roller moves up and down. That is the easy part. Because the fulcrum is off to one side, as the roller moves up and down, it is also levering forward and backward. This results in one or two coils being told to fire earlier than another one or two coils.
If you are running on battery, the cylinders will clearly fire early and late. If you are running on magneto, and the timer is off center by a significant amount, it is possible to have one cylinder fire 1/16 revolution early or late. That can cause either a solid backfire (evenly timed) or a very late and still "burning as it exits the valve" fire.
When we drive our Ts, we try to find the "sweet spot" where it runs its best. That spot is just before the engine begins to buck. That bucking is caused by one or more cylinders firing too early. It only takes one. So we set the timing so that the earliest firing cylinder will fire properly, while one or more cylinders will fire some variation of late (developmentally challenged). (That PC actually sort of works, it doesn't develop proper fire, pressure, and flow?) That late fire will heat valves and manifold for that cylinder more than the others do. You may or may not be able to detect that difference.
With front cover misalignment, it could be any cylinder.
This, I figured out about forty years ago because I had two successively fired cylinders that kept burning the exhaust valves. It was the front cover off center. I was getting less than 1000 miles out of those two valves. Everyone kept telling me I had an intake leak. Test after test found no leak anywhere on the intake path. So I figured it had to be the timing. Figured this out, fixed it, and no more burned valves (for years and many 1000s miles).

Concerns? Number three, a little glow after a hard pull or sit and idle for a while? No. The entire manifold glowing? Maybe.

Drive carefully, and enjoy, W2


Top of pagePrevious messageNext messageBottom of page Link to this message  By Norman T. Kling on Saturday, May 26, 2012 - 11:34 am:

Wayne,
That makes sense to me. Also, you will notice that the manifold bends near #3 causing the rear of the manifold to settle down. This would be most common when when using the flat gaskets but not using all 4 rings in the ports.
Norm


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