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| Intake manifold overheating https://slantsix.org/forum/viewtopic.php?t=59215 |
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| Author: | mcknight505 [ Tue Mar 01, 2016 7:49 pm ] |
| Post subject: | Intake manifold overheating |
I'm new to the forum and new to the slant six. I am having problems with the intake manifold getting too hot where the exhaust and intake bolt together. When the engine is at operating temperature and has ran for a period of time the intake manifold right above the exhaust and right below the carb will get upwards of 280 degrees Fahrenheit. Is this too hot? Also when it is that hot the truck will start to surge at about 50 mph and won't accelerate past that on any sort of a up hill slope. Any help will be appreciated P.S. I drive a 1982 dodge w150 4 speed Thank you Mcknight505 |
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| Author: | AMP762 [ Tue Mar 01, 2016 8:11 pm ] |
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Sounds like the heat riser may be stuck shut |
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| Author: | mcknight505 [ Wed Mar 02, 2016 6:57 am ] |
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What do you mean by heat riser? |
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| Author: | coconuteater64 [ Wed Mar 02, 2016 8:09 am ] |
| Post subject: | |
There is a diverter valve, commonly referred to as a "flapper", that directs exhaust heat to the bottom of the intake to improve cold weather driveability. If this gets stuck in the position where all of the exhaust gets directed to the bottom of the intake all the time, it can get really hot as you have seen. Having a heated intake manifold is not a bad thing on an inline engine, as carb icing can occur, or even below that threshold, the fuel can fall out of suspension as it makes the sharp right turn from carburetor to valve. Check to see if the bobweight on the exhaust manifold moves freely. |
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| Author: | mcknight505 [ Wed Mar 02, 2016 8:24 am ] |
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the weight does move freely. I was thinking about installing a set of headers or a manifold such as the dutra duals. my thinking was that it would solve the problem and add a little HP at the same time. what are your thoughts? |
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| Author: | coconuteater64 [ Wed Mar 02, 2016 8:49 am ] |
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If you live in a cold climate, you'll need some sort of manifold heat. Cold air into the carburetor helps the air carry more fuel because it is denser. But if the manifold is cold, icing can occur, or fuel puddling can happen. Cold air with a warm manifold will improve performance in the cold. The engine in my signature has dual Dutra manifolds and no carb heat. It's pretty much a summer only vehicle anyway, but if I drive it in the winter it definitely is no fun. The intake never really gets warm enough to aid in vaporizing the fuel. If you've ever flown a small aircraft you know all about carburetor icing. It's not something you want! It happened to me last Sunday as a matter of fact, at only 1100 feet MSL. It's caused by the drop in temperature caused by the venturi effect, and water droplets in humid air actually freeze. Next thing you know, you're losing power. For aircraft, there's an electric heater that will eliminate the problem. On a car, not so much. |
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| Author: | mcknight505 [ Wed Mar 02, 2016 9:55 am ] |
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I live in new mexico and in the winter it gets down to 10 and in the summer it gets over 100. my truck is driven year round. what do you think if I fabricated a ducting up to the bottom of the manifold much like what goes from the exhaust manifold to the air cleaner on some of the slants, if I went with an after market setup that doesn't bolt to the intake manifold. would that provide enough heat? |
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| Author: | Louise76 [ Wed Mar 02, 2016 11:29 am ] |
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coconuteater- PM me about Aircraft carb ice? |
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| Author: | coconuteater64 [ Wed Mar 02, 2016 3:24 pm ] |
| Post subject: | |
Sent |
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| Author: | Rick Covalt [ Wed Mar 02, 2016 4:14 pm ] |
| Post subject: | |
Quote: 280 degrees Fahrenheit. Is this too hot?
I don't really know that that is too hot? I would say you have hot exhaust blowing right against the intake on the bottom and then the manifold has exhaust runners the whole length of the intake. It is going to get hot. How hot, I'm not sure. Maybe someone else with a heat gun can check theirs for you.Rick |
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| Author: | coconuteater64 [ Wed Mar 02, 2016 4:36 pm ] |
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I'd like to know the normal temperature myself. Interesting. |
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| Author: | mcknight505 [ Wed Mar 02, 2016 5:09 pm ] |
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I just have a cheap temp gun from harbor freight I think it was like 25 bucks and seems fairly accurate. But if I put headers on it and rand a snorkel up to the base of the intake manifold kind of like how they do it from the exhaust to the air cleaner do you think that would be enough heat to keep it from icing? |
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| Author: | Rick Covalt [ Wed Mar 02, 2016 5:26 pm ] |
| Post subject: | |
I have Hooker super comp. truck headers and they have a small @ 3/4" steel tube that runs up from one of the header tubes to a plate that bolts up under the carb. It works well on my truck. I have run it for the last few weeks here in the cold PA weather and have had no cold weather issues. Any heat you can direct up under the carb should help. |
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| Author: | mcknight505 [ Wed Mar 02, 2016 5:31 pm ] |
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Ok cool thanks. where did you pick them up at? Price? And what model of truck do you drive? Thank you everyone for all the help |
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| Author: | Rick Covalt [ Wed Mar 02, 2016 6:20 pm ] |
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http://slantsix.org/forum/viewtopic.php?t=56667 That link shows you a general picture. The headers are hard to find and when you do they are pretty salty. I found mine on a clearance from someone on E-Bay about 2 years ago for $150. That was a steal. I think the last set of new ones I saw were close to $600 I'd keep my eyes open and you may find a used set. My truck is an 85 D100 |
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