1300cc exhaust single port heat riser issue

[narrowfarm]

Hello, my intake manifold has condensation by the carb. I took the intake manifold off and the heat riser tube is clear all the way through! I installed new gaskets for the intake manifold and heat riser tube.
I am thinking now that my after market GT style exhaust for my kit car is not working properly to create the difference in pressure to make the heat riser tube work. The exhaust does have openings for the heat riser tube.
Any ideas on how I could get a difference in pressure for the heat riser tube?? Do they make any different size gaskets I could use to get a difference in pressure from one side of the heat riser tube to the other side of the heat riser tube???
Is there a good after market exhaust that I may have to go to that is good for the heat riser tube single port??[/img]

[oprn]

Sweet car!

Very few after market exhausts have heat risers that work. I have seen gaskets with different sized holes and assumed that was what they were for but I cannot confirm as to how well they work. There are pictures on this site somewhere of exhausts modified to put one of the heat riser outlets into a low pressure portion of the muffler like the factory did.

[narrowfarm]

Wow thanks oprn !!! I just found some info on this site with pictures just like you said under heat risers outlets.
Looks like I am going to try to fix and weld up a new tube from he exhaust to the heat riser. I saw a few pictures of designs and saved them on my computer! Thanks again!!!

[BL3Manx]

One time on a Manx buggy while living back east, I actually fabricated an intake air pre-heater which picked up hot air off the surface of the muffler then ran it through a hose to the air cleaner.

The stock engine was designed to do the same thing

https://www.thesamba.com/vw/forum/viewtopic.php?p=4327378#4327378

[vponder]

I just had a another intake put on that had a clear heat riser, two weeks ago I drove it to a car show about thirty miles away the carb was wet and cool, I know the heat riser is getting hot checked it with a temp gun but the morning was cool and the humidity was prob up the buggy ran good.

[didget69]

Even if you drill out the riser holes in aftermarket headers, they still will not work properly.

Look at the way the stock VW muffler routes to the heat riser tubes to get a better understanding of why the aftermarket header heat risers don't work...

https://www.jbugs.com/store/graphics/00000001/Main-113251053AK-Stock-Exhaust-Front-No-Tailpipes.jpg

And, note that your sporty-looking Monza style exhaust is one of the more restricted exhaust systems available from an exhaust flow standpoint.

To use exhaust that you have, fabricate a longer run heat riser tube like stock Beetle muffler & modify one riser accordingly to tie-in to rest of exhaust.

Bryan
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I never found the need to impress people with any mechanic certifications, trophies or track wins... unless it was for Mom to post on the refrigerator door.