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[C1] Exhaust Manifold excessive temp

Old 04-22-2018, 05:05 PM
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Dave Tuten
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Default Exhaust Manifold excessive temp

Hello All,
Been trying to solve problem with high temperatue measured at ports of exhaust, specifically middle outlets. Temp reading per my harbor freight infrared red heat sensor I am seeing 650 f on right manifold and 615 on left. These readings vary up and down 20 degrees or so. I was told by this forum that the average should be around 450. I have verified timing on cam and crankshaft gears and the dot's line up. I have set timing from 4 degrees to 12 with no measurable heat difference. Changed intakes and get same. Exhaust seems to be fine but hot. Not sure what else I can check. Also, noticed that the coil got so hot it would burn your hand...wow whats with that? Any advice would be great, just don't know what else to check. thanks and have a great day.
1957 vette 283 w/ elderbrock 1406 carb sitting on 57 intake. Also was in garage when testing all this stuff...small garage just enough for car and maybe 3 feet on each side.
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Old 04-22-2018, 05:07 PM
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If I were you, I'd move on to the next best drama you can find.
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Old 04-22-2018, 05:08 PM
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check your jetting and rich conditions in your carb
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Old 04-22-2018, 05:40 PM
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You brought this up once before about 1-1/2 years ago:

https://www.corvetteforum.com/forums...eat-range.html

Has your engine broken down since then ?
Would you be happy if the temps were a uniform 450* all-round but the engine ran like crap ?
Don't try to tune your car by exhaust temps if its otherwise running fine. If you've set the timing right and the plugs don't read 'lean' quit worrying.
MikeM has given you good advice.

Last edited by Frankie the Fink; 04-22-2018 at 05:42 PM.
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Old 04-22-2018, 05:50 PM
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X3 here. Do you realize that more modern cars need to see a temp of 600 degrees at the catalytic converter to get it to light off? And that's a few feet downstream of the exhaust manifolds. And those engines run for 100's of thousands of miles. You're worrying over nothing, IMO. Same goes for folks who think running an engine at 200-210 degrees will burn it up. Nonsense.
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Old 04-22-2018, 06:04 PM
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My question is...was the car sitting in the garage the entire time...just idling for a good long while...and you are took the readings at that time???

Because...if you stop and think about it. Your engine was NOT made to just sit there and idle for extended periods of time. I know they can...but the engine is made to be used. Try taking it out for a good decent drive an then take your temp readings.

I agree with reading your spark plugs...they will tell you a lot...which can indicate some other performance characteristics that may need to be addressed. If you have smooth even idle and it stays like that for a good while....I would not worry about it. Because I deal with a lot of the fuel injected Corvettes where if they are siting for a good while...they can start to act up and the idle gets kinda weird. But I know this is normal and I take kit out for a quick test drive and get the plugs cleaned up and when I pull back into the shop..the idle is smooth again.

But I also tell many of my customers who go on the internet and read stuff...that often times getting caught up in 'numbers' can be dangerous. Trying to match what everybody else has can make you go crazy...especially if you are not over heating and have major performance issues.

As for the ignition coil getting hot. That also may be attributed to the car sitting in a garage in the heat and not having good air moving across it. The air flow flowing across your engine when it is sitting still and the hood up is not the same as your car going down the road. And if it is in a small garage and the hood is down and the engine is running for good long while...I guess you can assume that things under the hood are going to get really hot due to circulating the hot air in the garage.

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Old 04-22-2018, 06:24 PM
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Originally Posted by MikeM View Post
If I were you, I'd move on to the next best drama you can find.
and that would be what...
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Old 04-22-2018, 06:25 PM
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Originally Posted by Dave Tuten View Post
and that would be what...
"what motor oil should I use" would be a good start....

Bill
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Old 04-22-2018, 06:26 PM
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Originally Posted by Frankie the Fink View Post
You brought this up once before about 1-1/2 years ago:

https://www.corvetteforum.com/forums...eat-range.html

Has your engine broken down since then ?
Would you be happy if the temps were a uniform 450* all-round but the engine ran like crap ?
Don't try to tune your car by exhaust temps if its otherwise running fine. If you've set the timing right and the plugs don't read 'lean' quit worrying.
MikeM has given you good advice.
sorry, won't ask again...not sure about advice mikem was referring to
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Old 04-22-2018, 06:27 PM
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Originally Posted by Dave Tuten View Post
and that would be what...
Drive the car until somethingís breaks and fix that and move on
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Old 04-22-2018, 06:29 PM
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Originally Posted by wmf62 View Post
"what motor oil should I use" would be a good start....

Bill
you all have a great day
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Old 04-22-2018, 07:05 PM
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Originally Posted by Dave Tuten View Post
Hello All,
Been trying to solve problem with high temperatue measured at ports of exhaust, specifically middle outlets. Temp reading per my harbor freight infrared red heat sensor I am seeing 650 f on right manifold and 615 on left. These readings vary up and down 20 degrees or so. I was told by this forum that the average should be around 450. I have verified timing on cam and crankshaft gears and the dot's line up. I have set timing from 4 degrees to 12 with no measurable heat difference. Changed intakes and get same. Exhaust seems to be fine but hot. Not sure what else I can check. Also, noticed that the coil got so hot it would burn your hand...wow whats with that? Any advice would be great, just don't know what else to check. thanks and have a great day.
1957 vette 283 w/ elderbrock 1406 carb sitting on 57 intake. Also was in garage when testing all this stuff...small garage just enough for car and maybe 3 feet on each side.
Dave,

You might try a vacuum advance distributor and connect the vacuum advance to a full manifold source. This additional timing at idle speeds may reduce the temperature of the exhaust because the combustion process is started earlier so the heat energy pushes on the piston instead of being pushed out the exhaust.
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Old 04-22-2018, 07:14 PM
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Check your idle timing and vacuum advance.
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Old 04-22-2018, 10:09 PM
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If you do have a vacuum advance, make sure it is getting the vacuum signal from a constant vacuum source and not a ported source. On the Edelbrock 1406, the port on the front passenger side (the choke side) is ported. Don't use that one. Use the one on the driver side.
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Old 04-22-2018, 10:58 PM
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The premise seems to be that if your engine exhaust manifolds are running above 450* there is something wrong.

In 50 years of working on all manner of cars, motorcycles and boats, old and new, I never felt the need to measure exhaust manifold temperature. In fact, I donít remember anyone that did. Largely because there wasnít an easy way to do it for the home hobbyist. So, nobody worried about it.

So now we have this guy swapping parts with no other symptom of abnormality except whatís based on an internet opinion of what is normal exhaust temperature.

Yeah, I totally get it.

Last edited by Frankie the Fink; 04-22-2018 at 11:15 PM.
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Old 04-22-2018, 11:04 PM
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I checked the exhaust manifold temps with an IR gun years ago when I had an overheating problem on a small block and the highest I saw just short of 500 degrees.
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Old 04-23-2018, 06:16 AM
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Does anyone know if the OP's car even has a vacuum advance distributor? Most/all '57's didn't. If that's the case, the exhaust temperature will be a little higher than with VA.

As FTF pointed out, the OP seemed confused about how to set timing a year or so ago. He hasn't responded yet if he has that straightened out. He says he has set the timing from 4 to 12 degrees with no detectable difference in manifold temperature.

The stars are not aligning.

Last edited by MikeM; 04-23-2018 at 02:38 PM.
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Old 04-23-2018, 12:43 PM
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Originally Posted by tbarb View Post
Dave,

You might try a vacuum advance distributor and connect the vacuum advance to a full manifold source. This additional timing at idle speeds may reduce the temperature of the exhaust because the combustion process is started earlier so the heat energy pushes on the piston instead of being pushed out the exhaust.

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Old 04-23-2018, 01:17 PM
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Originally Posted by Dave Tuten View Post
Hello All,
Been trying to solve problem with high temperatue measured at ports of exhaust, specifically middle outlets. Temp reading per my harbor freight infrared red heat sensor I am seeing 650 f on right manifold and 615 on left. These readings vary up and down 20 degrees or so. I was told by this forum that the average should be around 450. I have verified timing on cam and crankshaft gears and the dot's line up. I have set timing from 4 degrees to 12 with no measurable heat difference. Changed intakes and get same. Exhaust seems to be fine but hot. Not sure what else I can check. Also, noticed that the coil got so hot it would burn your hand...wow whats with that? Any advice would be great, just don't know what else to check. thanks and have a great day.
1957 vette 283 w/ elderbrock 1406 carb sitting on 57 intake. Also was in garage when testing all this stuff...small garage just enough for car and maybe 3 feet on each side.
If you have a properly configured spark advance map, which includes a VAC that meets the Two-Inch Rule connected to a full time manifold vacuum source, manifold temps should be no more than about 500F, but you have to hold the gun close because it reads a "cone" and averages it, so if you don't hold it close it will average what it sees, which could include cooler background objects.

The manifolds rapidly radiate heat, so the temp will vary along the length, and the center is likely the hottest because of the two siamized ports.

You need to tell us about the existing spark advance map, vacuum @ idle speed, and the number on the VAC. The manifold and carb don't have any influence as long as the carb signal to the VAC is full time, and the idle mixture is reasonable.

Duke

Last edited by SWCDuke; 04-23-2018 at 01:21 PM.
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Old 04-23-2018, 03:13 PM
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I just put my palms over my tail pipes while the engine was running and the exhaust felt too hot to me.....should I run a colder range plug ?

I'm thinking ACR44s would cool things down...
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