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bokuglen Samba Member
Joined: June 14, 2006 Posts: 43 Location: Southeast Pennsylvania
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Posted: Thu Jan 18, 2018 1:52 pm Post subject: Warm Air Intake for progressive carb |
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I have a Weber progressive center mount in my 74 bus. I'd like to make a nice warm air intake, pulling air off the exhaust manifold, to make it run better in general. I've seen a few ideas on the forums, but wonder if someone has other ideas and photos to post? |
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busdaddy Samba Member
Joined: February 12, 2004 Posts: 51149 Location: Surrey B.C. Canada, but thinking of Ukraine
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alman72 Samba Member
Joined: October 09, 2014 Posts: 2573 Location: MICHIGAN
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Posted: Thu Jan 18, 2018 2:51 pm Post subject: Re: Warm Air Intake for progressive carb |
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all the pics of the cookie tin mod/hack are dead links.....Another reason to put your pics here on the Samba! |
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Wildthings Samba Member
Joined: March 13, 2005 Posts: 50351
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Posted: Thu Jan 18, 2018 4:25 pm Post subject: Re: Warm Air Intake for progressive carb |
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Get the stock air preheat tin that pulls air off the right front cylinder, you can find it in the classifieds from time to time. The cylinder heats a lot faster than the exhaust. When I built my system almost thirty years ago I used the right heater box as a heat source but later changed it to use the stock 72-74 tin. This is my early setup which I ran for years but later altered.
I also have a heated manifold using hot exhaust gas from the left side of the muffler. Just adding the preheated air should take care of any icing issues and then modifying the operation of the power valve in the carb should take care of any remaining bog (assuming the carb is tune pretty well to start with).
The center section of the manifold is doubled walled, so the heat gets right to the base of the carb.
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busdaddy Samba Member
Joined: February 12, 2004 Posts: 51149 Location: Surrey B.C. Canada, but thinking of Ukraine
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Posted: Thu Jan 18, 2018 6:11 pm Post subject: Re: Warm Air Intake for progressive carb |
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alman72 wrote: |
all the pics of the cookie tin mod/hack are dead links.....Another reason to put your pics here on the Samba! |
Dammit! , sorry I didn't look to see if they still worked, bummer, that was an excellent thread. _________________ Rust NEVER sleeps and stock never goes out of style.
Please don't PM technical questions, ask your problem in public so everyone can play along. If you think it's too stupid post it here
Stop dead photo links! Post your photos to The Samba Gallery!
Слава Україні! |
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Rodmullet Samba Member
Joined: May 27, 2010 Posts: 196 Location: New Jersey
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Posted: Thu Jan 18, 2018 10:42 pm Post subject: Re: Warm Air Intake for progressive carb |
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Well, I don't have pictures handy at the moment....
My bus still had the original warm air "donut" attachment for the original air cleaner....it is on the right front (front is front) of where the single carb is. I, using some real hacks (small tin pineapple can and a clamps) attached a piece of flexible metal tubing to this hot air source. Had a big cookie tin....attached hose to cookie tin adapted to enclose air cleaner. Mine is very basic....I'm sure most here could do it much more gracefully,
I also made a tent of sorts out of reflectix bubble wrap insulation that loosely surrounds the intake runners all the way to where the intake bolts to the heads, this actually trapped enough heat to keep the runners very warm to the touch...I'll try to find or take some pictures tomorrow. |
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alman72 Samba Member
Joined: October 09, 2014 Posts: 2573 Location: MICHIGAN
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Posted: Fri Jan 19, 2018 4:56 am Post subject: Re: Warm Air Intake for progressive carb |
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busdaddy wrote: |
alman72 wrote: |
all the pics of the cookie tin mod/hack are dead links.....Another reason to put your pics here on the Samba! |
Dammit! , sorry I didn't look to see if they still worked, bummer, that was an excellent thread. |
the actual cookie (sugar)thread still has pics, so there is that. |
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Rodmullet Samba Member
Joined: May 27, 2010 Posts: 196 Location: New Jersey
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Posted: Sat Jan 20, 2018 5:34 pm Post subject: Re: Warm Air Intake for progressive carb |
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Well, I took some pics of mine....again, not real elegant, but inexpensive enough for experimental purposes...if I am happy with how the bus runs, I can spend a few bucks and get fancier. Couldn't get a shot of how the hose attaches to the warm air intake for the original dual carb air cleaner, as the there's a ton of stuff in the cargo area and the bus is in a very tight parking space. Hope it helps.
Ran very well when the temps were in the fifties and a bit damp.
Rod |
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Wildthings Samba Member
Joined: March 13, 2005 Posts: 50351
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Posted: Sat Jan 20, 2018 6:07 pm Post subject: Re: Warm Air Intake for progressive carb |
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Rodmullet wrote: |
Ran very well when the temps were in the fifties and a bit damp.
Rod |
I would think that you would have a bad case of heat soak when you shut your engine down on a hot day with the manifold covered like that. I actually have a shield under my carb to keep the heat away from the carb after shutdown and only have the outer ends of my runners wrapped. |
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Rodmullet Samba Member
Joined: May 27, 2010 Posts: 196 Location: New Jersey
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Posted: Sat Jan 20, 2018 6:14 pm Post subject: Re: Warm Air Intake for progressive carb |
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The beauty of this is that it is easily removed as the weather changes...over about 60 degrees or so it isn't necessary. |
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vwwestyman Samba Member
Joined: April 24, 2004 Posts: 5688 Location: Manhattan, Kansas, USA
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Posted: Sat Jan 20, 2018 6:24 pm Post subject: Re: Warm Air Intake for progressive carb |
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When I had the progressive carb on my Bus, I just sorta shoved the tube into the hot air intake from the head. It still had the rubber donut/gasket there, so I found a tube that fit tightly into it.
I never built anything special by the air cleaner, I just bent the tube so it was aimed right at and pressed against the air cleaner a bit, on the assumption that it would suck in some hot air. I don't know how much it really worked...
That's why I installed fuel injection! _________________ Dave Cook
President, Wild Westerner Club
1978 Champagne Edition Westy, repowered to '97 Jetta TDI
1973 Wild Westerner
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orwell84 Samba Member
Joined: May 14, 2007 Posts: 2539 Location: Plattsburgh, New York
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Posted: Sat Jan 20, 2018 6:26 pm Post subject: Re: Warm Air Intake for progressive carb |
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I wonder how carburated airplanes provide heat for carbs. Usually carb heat is switched on before takeoff as icing can cause insufficient speeds for takeoff. I think it is also used during landings in the event that maximum power must be used to climb quickly in case of a missed approach. |
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vwwestyman Samba Member
Joined: April 24, 2004 Posts: 5688 Location: Manhattan, Kansas, USA
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bokuglen Samba Member
Joined: June 14, 2006 Posts: 43 Location: Southeast Pennsylvania
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Posted: Sat Jan 20, 2018 6:52 pm Post subject: Re: Warm Air Intake for progressive carb |
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Rodmullet wrote: |
Well, I took some pics of mine....again, not real elegant, but inexpensive enough for experimental purposes...if I am happy with how the bus runs, I can spend a few bucks and get fancier. Couldn't get a shot of how the hose attaches to the warm air intake for the original dual carb air cleaner, as the there's a ton of stuff in the cargo area and the bus is in a very tight parking space. Hope it helps.
Ran very well when the temps were in the fifties and a bit damp.
Rod |
Rod - Thanks ! Very useful information. How did you mount that cookie tin on the carb? And, did you have any trouble with that Reflectix insulation melting? |
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Wildthings Samba Member
Joined: March 13, 2005 Posts: 50351
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Posted: Sat Jan 20, 2018 7:05 pm Post subject: Re: Warm Air Intake for progressive carb |
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vwwestyman wrote: |
Some big diesel trucks have air intake heaters.
Here are a couple examples, google Intake Heater for lots of others. I have no idea how hot they get, but something like this might be worth experimenting with if you want to make these carbs work.
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I have heard that such was once available for the some style Weber carb. I have thought about using self regulating heat tape, maybe short sections wired in parallel to get the tape to work on 12v.
For what its worth, my system really didn't take me long to build and has lasted a very long time. I would like to redo it using stainless steel or aluminium some day. |
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Wildthings Samba Member
Joined: March 13, 2005 Posts: 50351
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Posted: Sat Jan 20, 2018 7:24 pm Post subject: Re: Warm Air Intake for progressive carb |
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Any idea as to the actual application for this heater? Looks to be fairly easy to install. |
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vwwestyman Samba Member
Joined: April 24, 2004 Posts: 5688 Location: Manhattan, Kansas, USA
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Rodmullet Samba Member
Joined: May 27, 2010 Posts: 196 Location: New Jersey
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Posted: Sat Jan 20, 2018 8:24 pm Post subject: Re: Warm Air Intake for progressive carb |
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Bokuglen
I've only done short trips (7 miles) with the reflectix...I suppose it could get hot enough to melt, but it isn't wrapped tightly, it is more like a tent to hold some heat in. As I recall, the reflectix was not that warm to the touch, but the intake runners were quite warm after my test runs. My original idea was to get some very lightweight sheet steel or aluminum and make sort of a tent or tunnel to serve the same purpose ( to direct some of the heat from the heads and engine case to the intake runners)....but the reflectix was on hand for test purposes, and is easy to form to the shape I wanted...the reflectix website says max temp is 180 F. , so it is probably a good idea to do some temp checks. Someone much smarter than I am probably knows how hot the engine bay gets at operating temperature.
For the cookie tin, which does direct some quite warm air into the carb, I just cut the bottom of the tin the same way the air filter base is , then just sandwiched it between the carb and the bottom piece of the air cleaner. I used a pretty big cookie tin, as well.
Hope that made sense.
Rod |
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Wildthings Samba Member
Joined: March 13, 2005 Posts: 50351
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Posted: Sat Jan 20, 2018 8:54 pm Post subject: Re: Warm Air Intake for progressive carb |
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Wildthings wrote: |
Any idea as to the actual application for this heater? Looks to be fairly easy to install. |
The manifold is certainly very crude looking, maybe early to mid seventies.
. |
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aerosurfer Samba Member
Joined: March 25, 2012 Posts: 1602 Location: Indianapolis, IN
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Posted: Sun Jan 21, 2018 8:35 am Post subject: Re: Warm Air Intake for progressive carb |
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orwell84 wrote: |
I wonder how carburated airplanes provide heat for carbs. Usually carb heat is switched on before takeoff as icing can cause insufficient speeds for takeoff. I think it is also used during landings in the event that maximum power must be used to climb quickly in case of a missed approach. |
Close but not at all....
Carb hear is checked during the run up before takeoff, but it robs power you typically don’t want it on then, same goes with landing in case of a go around or rejected landing.
In a plane you only want it on long enough to melt any ice forming within the carb/intake runners then turn it back off. The high power settings isn’t when carb ice usually forms either, it’s the partial power setting and descent power (at or near idle) where it’s more common to form, when there is a low temperature-dew point spread and high humidity.
More info....
https://www.rainierflightservice.com/blog/carburetor-ice/ _________________ Rebuild your own FI Harness..My Harness
77 Westy 2.0L Rockin and Rolling Resto!
72 Sportsmobile (sold)
79 Tran$porter... Parts car money machine (gone) |
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