Plugged heat riser tube - acetylene?

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EskimoTom
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Plugged heat riser tube - acetylene?

Post by EskimoTom » Sat Jun 11, 2016 4:23 pm

I'm new. My appointment with Colin is June 26. I pulled the 1600 DP from my 71 bus. Was chasing down source of smoking engine, looks like leaking oil cooler. Meanwhile, blew into manifold heat riser, apparently plugged. I recall, somewhere in Itenerant Aircooled, a procedure using acetylene to blow out and clear a plugged heat riser. It may have been elsewhere. Can anyone point me to how to do that? A link? I tried a search here to no avail. Thanks, Eskimo Tom in MN.
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MonoCone
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Re: Plugged heat riser tube - acetylene?

Post by MonoCone » Sat Jun 11, 2016 8:27 pm

Couple of ideas. A short length of old clutch cable, chucked into a drill, and then run backwards to try to grind out the carbon. Running it in reverse is to avoid the cable unwinding. Another way is to heat up the carbon with a torch. I used to have a propane torch that also had an oxygen bottle. Heat the carbon up really hot and then turn the oxygen way up. Sparks flew and most of the carbon burnt itself out. I have talked to people who use acetylene in the same way.

If it will not come out (or you have holes in the heat riser) replacement German manifolds and pretty cheap in the Samba classifieds. Just make sure the heat risers tubes are open!
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wcfvw69
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Re: Plugged heat riser tube - acetylene?

Post by wcfvw69 » Sat Jun 11, 2016 8:52 pm

I've never tried the torch method though I may now that I have a torch. I've had luck with cable bought at Home Depot. You have to cut a few different lengths. A short one to start off as the carbon seems to always be harder at the ends. Then a longer one to get it out deep down the tube. It's laborious and a pain in the butt but it works. It also makes our center mounted carbs so very happy.
1970 Westfalia bus. Stock 1776 dual port type 1 engine. Restored German Solex 34-3. Restored 205Q distributor, restored to factory appearance engine.

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hambone
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Re: Plugged heat riser tube - acetylene?

Post by hambone » Mon Jun 13, 2016 12:54 pm

I would also add water into the pipe, as it heats up it really helps break that stuff down, sputters and coughs.
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kreemoweet
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Re: Plugged heat riser tube - acetylene?

Post by kreemoweet » Mon Jun 13, 2016 8:48 pm

It's more than just carbon - there's plenty of rust in an old heat riser tube also. If you've ever seen how plugged up an old galvanized
water pipe can get with rust, you'll have some idea of what you're up against. I've found that just firmly tapping the heat riser with
a plastic or firm rubber hammer, repeatedly, will cause a steady rain of old carbon/rust to drop out of the tube. Bonk, bonk, bonkety-bonk,
making the tube ring, as long as stuff keeps breaking loose, will extract an enormous pile of crud.

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