The Stovebolt Site Forums The Shop Area Engine Shop 66 heat riser - toss or no ? single or duel ex ?

heat riser is rusted in place. after lots of wd i was finally able to force it about 1/3 -1/2 open.
stock single exhaust system is history.
what is your advice ?
should i go with single exhaust or duel ?
should i delete the riser or keep the riser ?
my carb is manual choke 2 jet - 283 auto.
thanks
in advance.
paul

I'd dump the riser and run a set of duals. But that's just me.

P.Dow, I'm not a professional mechanic but in my opinion the heat riser is a useful device because it helps an engine to warm up quickly. The sticking heat riser is a problem that I have also had on two of my vehicles, a '71 Dodge van that I bought new and a '36 Chevy pickup that I restored in the early 1970s. I still have both of these vehicles.

Well over 25 years ago I made a modification that has permenantly cured the problem. I drilled the heat riser shaft holes in the exhaust manifolds oversize and made and pressed in stainless steel bushings and I made stainless steel shafts for the heat riser valve. Now, there is nothing to rust and no sticking.

With regard to dual exhaust, when I built a dual exhaust for the van, which at the time had a bone stock 318 V8, fuel economy immediately increased by about 1 1/2 MPG. The dual exhaust incorporated an H-pipe, that reduces noise and according to performance experts also increases power. Not having a dynomometer, I can't comment on the effect of the dual exhaust on power.

If you want any details of the stainless steel parts I made please feel free to email me at [email protected]. I hope this helps!

interesting.
i knew dual helped engine breath, increase hp to a point but it hadnt occured to me mpg would be improved.
stainless option may be more than i would do but is good to be aware of.
thanks

Auto companies dont come up with these things just for fun. They are on there because some units wont run RIGHT without them.Your choice.

I agree, keep it. Especially if you're keeping the engine relatively stock, no headers or aftermaket performance parts. Forget using WD40, though. Get a real penetrant oil, like Kroil or PB. Might also try heat cycling it with a small torch in addition to the penentrant. I do like yars idea on the stainless bushings (bronze would work, too). Riser will work fine with duals.

riser with duals.
might go that way.
in looking in the 58 shop manual i just got.... i think it said the riser helps decrease moisture/condensation (overtime)
problem in the motor compartments.
probably does other things too.
.... right you are about wd i actually use the pb blaster ... had a brain fart and fogot its name.. so called it wd.

Go with duals, also check the exhaust manfolds. In some there was a butterfly in the collector area, that also would stick shut. This may be what you are talking about. There also was a riser in association with the intake manifold. Either that or I was abducted by aliens.

That's the one I was referring to. No value in my opinion.

That is the heat riser valve. It partially blocks the exhaust flow when the engine is cold, forcing it to go through the passage in the intake manifold. This makes for faster warmup, better feul atomization, and reduced carburetor icing.

The additional back pressure negates those cold engine advantages in my opinion.

aliens may be nearer than we know......

to be crystal clear it is the heat riser on the passenger exhaust manifold-meets the exhaust pipe that crosses over to the drivers side meets that exhaust bank then goes back to the muffler.
only one riser.
if that isnt clear... then- i am a alien.

paul

Once the engine is warmed up, the riser opens, no backpressure issue at that point.

probably a fully functional riser is best.
one that is stuck or responds sluggishly would indeed be counter productive. agreed.

I guess we'll just have to agree to disagree.

Anything in there creates some back pressure, albeit a small amount. The better an engine can breath (in and out), the better it will perform - just my opinion.

i was thinking about this.
it seems to me if the riser function was a manual control item- rather that a counter weight dummy system it might be a fair comprimise.
it could be a system where a fella had a pull - like a choke pull -
where by he could manually do the same thing a good working riser would do...
but it could be used optionally.

but i think vetteman is a purest and doesnt want anything in his exhausts way...

Paul, here's something to consider when listening to people talk about exhaust restriction from a heat riser. The exhaust is the "exhale" side of the engine's pulmonary system. The engineers who designed that engine balanced the capability of the "inhale" and the "exhale" sides.

That means that at full throttle on the intake side the exhaust system is at it full capacity too. Only a tiny amount of normal driving is done at full throttle. That means that in almost all situations the exhaust system is handling vastly less exhaust gasses than it is capable of. Thus the heat riser has no practical adverse effect.

Also, when in the open position the heat riser exposes only the edge of a piece of sheet metal and a small diameter shaft to the flow of exhaust gasses. There is no doubt that gas flow around that will be laminar, not turbulent.

Finally, don't be intimidated by stainless steel. It is a common hardware store item in the form of bolts in a wide range of sizes. Those bolts can be used to make the shaft and bushings. If you don't have a way to drill a hole in the bushings, send the pieces to me and I will drill the holes for you. If you like I'll send you my address. In that case please email me at [email protected]

I am neither a metalurgist nor a chemical engineer but I doubt that stainless steel has an equal in applications that are exposed to exhaust gas flow. Again, I made this modification in both my '71 Dodge van V-8 and my restored '36 Chevy pickup engines over 25 years ago and it has worked perfectly.