"aberson Bresident of the FullyAssed Committe" (emaxxbl)
06/01/2019 at 12:09 • Filed to: None
1
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"aberson Bresident of the FullyAssed Committe" (emaxxbl)
06/01/2019 at 12:09 • Filed to: None | 1
| 13 |
So the 400 in the xjs was a smog era engine out of a ‘74 monte carlo and it still
had the factory smog ramhorn manifolds on it, one of which had this little valve sandwiched between the downpipe and manifold. There was nothing connected to it and no other outlets anywhere on it so i’m kinda at a loss as to what its intended purpose may be.
Alfalfa
> aberson Bresident of the FullyAssed Committe
06/01/2019 at 12:17 |
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Go ogle-fu to the rescue!
Manwich - now Keto-Friendly
> Alfalfa
06/01/2019 at 12:34 |
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Hmmm... I wonder how that heat riser valve actually helps an engine to warm up.
I don’t understand how putting a valve in the exhaust can cause an engine to warm up faster.
DipodomysDeserti
> Manwich - now Keto-Friendly
06/01/2019 at 12:44 |
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Keeps hot exhaust in the exhaust manifold longer which helps get everything hotter, faster. On V engines there’s usually a crossover pipe which channels the exhaust below the carb.
My X-type is too a real Jaguar
> Alfalfa
06/01/2019 at 12:44 |
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It also says it can cause DANGER TO MANIFOLD so it’s a speed part.
and 100 more
> Manwich - now Keto-Friendly
06/01/2019 at 12:57 |
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IIRC, it takes in hot air from around the manifold (not exhaust) and pipes it into the intake.
Nevermind, I’m wrong, just ignore what I wrote above.
Dash-doorhandle-6 cyl none the richer
> My X-type is too a real Jaguar
06/01/2019 at 13:08 |
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we all know its really a danger to floorboard though.
beardsbynelly - Rikerbeard
> Manwich - now Keto-Friendly
06/01/2019 at 13:12 |
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The ones I’ve seen block the gas going down one manifold and send it by the carb and out through the other manifold. They help the carb warm up faster.
Danimalk - Drives a Slow Car Fast
> aberson Bresident of the FullyAssed Committe
06/01/2019 at 13:14 |
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An early active exhaust valve.
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beardsbynelly - Rikerbeard
> aberson Bresident of the FullyAssed Committe
06/01/2019 at 13:18 |
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that tube coming out the side was probably plumbed into the air intake or a port near the carb to stop it icing up on cold starts.
Not an expert and not familiar with landbarge era engines but the vintage tractor
I
played with in my youth
worked by
closing the flap and
and sending
the gas through the tube to warm the carb up and then out through the other manifold.
Nibby
> aberson Bresident of the FullyAssed Committe
06/01/2019 at 13:24 |
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blinker fluid chamber
shop-teacher
> aberson Bresident of the FullyAssed Committe
06/01/2019 at 15:54 |
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Its a heat riser. Keeps the carb from icing up in the winter.
jimz
> Manwich - now Keto-Friendly
06/01/2019 at 19:31 |
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it doesn’t help the engine warm up, really. it redirects exhaust heat up to the intake to warm the air-fuel mixture in a cold engine. the problem with a cold spark-ignition engine is that the carburetor/injectors are admitting cold fuel into a cold engine. cold fuel doesn’t evaporate very quickly, which means in a cold engine there isn’t enough vaporized fuel to ignite reliably. So the carb/PCM has to add more fuel (cold enrichment) just to make sure there’s enough for it to reliably ignite, and the excess which doesn’t evaporate and burn just condenses on the cylinder walls and gets into the oil. heat risers duct exhaust heat up to the intake to make sure the air:fuel charge gets warm as possible to make sure all of the fuel evaporates.
MM54
> aberson Bresident of the FullyAssed Committe
06/02/2019 at 19:48 |
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As others have said, it’s a heat riser valve. When the engine is cold it’s closed, and it forces exhaust up to warm the carb/intake. As things warm up a bimetal spring open the flap, redirecting less exhaust up top. The fast warmup reduces emissions, and the overall system does a good job of making the engine not run as well, since you don’t want a hot intake...