Talk to Me about Heat Risers

[bajajoaquin]

Looking under my '67 Imperial today, I got a pleasant surprise: My right side exhaust down tube isn't being held on by bailing wire. It's perfectly sound and secure.

The down side of this information is that the bailing wire is being used to hold the heat riser closed. (So it doesn't send heat to the carb).

How much does this matter? Is it fixable? Rock Auto didn't show any parts for the heat riser. When I put on an Eddy carb later this week, is it going to be an issue?

(Wait a second! does this vent exhaust to the manifold to run the "hot air" chokes?)

 

[70bigblockdodge]

When this is closed it forces exhaust to flow through crossover in intake manifold raising the temp causing better atomization at low temps, some had a thermostatic spring that released tension as warmed up.

 

[bajajoaquin]

Sorry, meant wired open.

Is it repairable?

 

[MrMoparCHP]

Sorry, meant wired open.

Is it repairable?

Its wired open because you're in San Diego.
The two days a year that it gets cold you may have a rough start and it will take a little longer to warm up.
Many people an now blocking off the intake heat ports for different reasons, my mechanic advised me to.

Alan

 

[70bigblockdodge]

With the way fuel vaporises nowadays and the fact that your in San Diego just leave it.

 

[MrMoparCHP]

With the way fuel vaporises nowadays and the fact that your in San Diego just leave it.

What he said.

 

[bajajoaquin]

Bueno para evar.

(That's spanglish for "good to go")

Thanks.

 

[73Coupe]

I have a problem with hard starting when hot, and beginning to wonder if my heat riser is stuck closed, or at least not opening all the way.

The shaft rotates freely when I play with it, but I can't notice movement when the engine is started. I can't see the bimetal spring...I think it's located behind the counterweight? And on the backside, the bushing is loose and out of the manifold - I got a leak there.

Question: Which direction is it supposed to rotate to "OPEN" when looking at the engine from the front?

I would like to make sure it's open. And possible wire it open for now. I plan to eventually eliminate the riser as I live in CA. Also would like to find out a way to block off the intake manifold exhaust crossover.

Thanks,

 

[70bigblockdodge]

Fel pro sells a valley pan with the heat crossover blocked.

 

[mr. fix it]

you still have to keep that Heat riser in the open state though the valley pan along will not do the trick.
In fact it can cause burned exhaust valves and a hotter running engine...if stuck in the closed position
The occasional vapor lock can happen as well...

 

[vdk2010]

When I asken about the heat riser, I was told just to remve it, tap the hole and put a screw in, because it's gonna be a good weather car anyway...

 

[tallhair]

[h=2]Talk to Me about Heat Risers

[/h]
I'm against em

 

[70bigblockdodge]

When I asken about the heat riser, I was told just to remve it, tap the hole and put a screw in, because it's gonna be a good weather car anyway...

That's what I would do.

 

[68Bigred]

I need to ask a stupid question. I removed my heat riser totally when I rebuilt my motor and had my exhaust manifolds painted, but my intake manifold valley pan still allows the crossover. I have been meaning to replace it to block it off. I figure in TX no way do I need it and would rather the manifold get no hot exhaust thru it. When stuck in traffic my car starts to act up a bit on really hot days. Now here is my stupid question. Why do some of the valley pans come with the 4 gaskets and the metal pan and some dont? Are you supposed to use the gaskets on either side of the valley pan on each head? Wouldnt that cause a gap somewhere easpecially where the 4 bolts go on the front and back of the pan? I've never used them and never had a problem.

 

[70bigblockdodge]

I never use them on uncut stock heads and manifolds. However the heads I have for my Barracuda are milled on the intake face to allow the use of the paper gaskets with the valley pan, and I would assume this is so I don't have to replace the valley pan every time.

 

[BIGBARNEYCARS]

The Fel-Pro valley pan with the block off holez blocked off iz #1215 and comez with 4 paper gasketz if anyone needz to know. Those exhaust gassez eat the aluminum in the block off platez that are part of the cross ram set up iz how I know this Fel-Pro # so well, Jer

 

[68Bigred]

how long does it last before it blows thru. I do less then 2,000 miles a year. I would assume I should get many years out of it.

 

[commando1]

I will do what it reasonably takes to keep the heat riser.
If you have the log sitting on the bench, then it is easy.

 

[bajajoaquin]

I will do what it reasonably takes to keep the heat riser.
If you have the log sitting on the bench, then it is easy.

There was a write-up on the Imperial group about the heat riser, and made a pretty compelling case that it's wise to keep them, even in a place like So Cal. So the sentiment "reasonably takes" is probably exactly right.

 

[commando1]

This heat riser thing of mine is due to my "developement" years.
As part of the complete tune up on customer's car, we had to make sure the heat riser was working.
Winter or summer. The difference in cold starts is very noticable.