choke choking the car ...
11-12-2010, 09:17 AM
#1
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choke choking the car ...
well no it's not a joke ... :-)
I have problems adjusting choke (automatic) on my Demon carburetor.
When cold the choke butterfly closes fully. It is shaped in such a way that it would actually allow some air into the venturis, but it seems as it were not enough.
When I have the fast idle too quick or accellerate a bit the car sputters, dumps raw fuel through the exhaust pipe. very same thing as when you have a warm car, block the front venturis with hand, leave the tiniest gap. you can't give it any throttle without dying
car runs perfect when warm. when I get the fast idle reduced then it idles too low when cold (dies), and if I give it more the engine chokes
I have seen in the past that when you rev the engine (with choke fully closed) that the butterfly would open for a bit the time you throttle it and close back again. mine doesn't seem to do that
other than cutting a bit more off the butterfly (to allow more air) ... anything else you could think off? as it is currently it would be easier to remove the choke altogether and step on the accellersator for 5 mins to warm the engine, then drive off ...
Kalli
I have problems adjusting choke (automatic) on my Demon carburetor.
When cold the choke butterfly closes fully. It is shaped in such a way that it would actually allow some air into the venturis, but it seems as it were not enough.
When I have the fast idle too quick or accellerate a bit the car sputters, dumps raw fuel through the exhaust pipe. very same thing as when you have a warm car, block the front venturis with hand, leave the tiniest gap. you can't give it any throttle without dying
car runs perfect when warm. when I get the fast idle reduced then it idles too low when cold (dies), and if I give it more the engine chokes
I have seen in the past that when you rev the engine (with choke fully closed) that the butterfly would open for a bit the time you throttle it and close back again. mine doesn't seem to do that
other than cutting a bit more off the butterfly (to allow more air) ... anything else you could think off? as it is currently it would be easier to remove the choke altogether and step on the accellersator for 5 mins to warm the engine, then drive off ...
Kalli
11-12-2010, 09:32 AM
#2
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ya, just checked on the choke manual from demon. there's no choke pulloff
http://www.barrygrant.com/fromBarryG...structions.pdf
The choke plate is shaped in such a way to allow a bit of air in. So either I will re-shape that or I'll see if I can bend the choke rod so that the choke butterfly necver fully closes.
I've even tried to fit a holley choke (fro m my street avenger), but the choke pulloff is in the way at the demon, so they can't be interchanged :-(
http://www.barrygrant.com/fromBarryG...structions.pdf
The choke plate is shaped in such a way to allow a bit of air in. So either I will re-shape that or I'll see if I can bend the choke rod so that the choke butterfly necver fully closes.
I've even tried to fit a holley choke (fro m my street avenger), but the choke pulloff is in the way at the demon, so they can't be interchanged :-(
11-12-2010, 09:47 AM
#3
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Well from looking at the PDF is appears the housing containing the bimetallic strip can simply be rotated thus preventing the choke plate from fully closing.
When cold simply loosen the 3 screw around the housing and rotate the housing until the choke opens a bit.
I dont know sounds too simple to me.
-Gun
When cold simply loosen the 3 screw around the housing and rotate the housing until the choke opens a bit.
I dont know sounds too simple to me.
-Gun
11-12-2010, 10:56 AM
#4
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turning the choke housing only affects how long the choke will stay on.
if you turn it towards lean like it will still fully close, but open already after 30 seconds and fully open after 40. if you go towards rich then it will stay fully closed for a few minutes
Holley has a choke pull off under the pod, so that when you accellerate, the butterfly is opening to prevent the issue I'm having
see the silver cast cylinder sticking out next to black housing? bottom right in picture
even my old autolite 2100 has that.
here's the demon auto choke:
see, no pull of piston and see the square cuts in butterfly where the split pins are in picture? that's the only thing demon seemed to have done to prevent my problem. If the plate is closed my engine simply doesn't get enough air. if i try to accellerate slow or quick it will stall at 800-900 revs
it is torture for the engine and my heart in the first 5 minutes in the morning to try and keep the engine alive. I wouldn't be surprised if birds fall off the trees behind me. it sputters and pops.
if I disabled the choke completely then i have the usual problems (have to leave my foot on accellerator for 3 mins solid before I can drive without stalling). But that's exactly what I got a choke for
if you turn it towards lean like it will still fully close, but open already after 30 seconds and fully open after 40. if you go towards rich then it will stay fully closed for a few minutes
Holley has a choke pull off under the pod, so that when you accellerate, the butterfly is opening to prevent the issue I'm having
see the silver cast cylinder sticking out next to black housing? bottom right in picture
even my old autolite 2100 has that.
here's the demon auto choke:
see, no pull of piston and see the square cuts in butterfly where the split pins are in picture? that's the only thing demon seemed to have done to prevent my problem. If the plate is closed my engine simply doesn't get enough air. if i try to accellerate slow or quick it will stall at 800-900 revs
it is torture for the engine and my heart in the first 5 minutes in the morning to try and keep the engine alive. I wouldn't be surprised if birds fall off the trees behind me. it sputters and pops.
if I disabled the choke completely then i have the usual problems (have to leave my foot on accellerator for 3 mins solid before I can drive without stalling). But that's exactly what I got a choke for
Last edited by kalli; 11-12-2010 at 11:30 AM.
11-12-2010, 11:52 AM
#5
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well it looks like I'm not the only one with that problem. googled around and found:
I have a spare one (demon choke butterfly). So I'll give both ideas a try (bend the linkage to try and make sure the plate never fully closes). and if that fails cut the butterfly
I have a spare one (demon choke butterfly). So I'll give both ideas a try (bend the linkage to try and make sure the plate never fully closes). and if that fails cut the butterfly
Last edited by kalli; 11-12-2010 at 11:56 AM.
11-12-2010, 12:03 PM
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11-12-2010, 03:21 PM
#7
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Okay so work with me on this one. The coil strip simply expands or contracts with temperature making the radius larger or smaller. As this radius changes size it changes distance and in doing so moves the choke plate open or closed.
IF we rotate the housing when the car is cold this should begin to pull the choke open until you find a nice spot. Well the strip cant close the choke any further because it already cold all it can do now is open it and maybe with some luck it will return to the same place when it cold again.
What did I miss?
-Gun
IF we rotate the housing when the car is cold this should begin to pull the choke open until you find a nice spot. Well the strip cant close the choke any further because it already cold all it can do now is open it and maybe with some luck it will return to the same place when it cold again.
What did I miss?
-Gun
11-13-2010, 09:40 AM
#9
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I think I would drill holes way before I attacked my carb with a cut off wheel.
Holes could look pretty good, the way the choke plate in the picture is hacked off I doubt that it is very effective in colder temperatures, and a gaping hole does not lend much to adjustability.
As a kid I remember that black smoke from the tailpipe in a car (auto choke) that was "warming up" was pretty much the rule and not the exception, although with most of the newer carbs my experience has thus far been pretty good with auto chokes.
Surely there is a way to block open or otherwise limit the motion of the choke butterfly.....
Holes could look pretty good, the way the choke plate in the picture is hacked off I doubt that it is very effective in colder temperatures, and a gaping hole does not lend much to adjustability.
As a kid I remember that black smoke from the tailpipe in a car (auto choke) that was "warming up" was pretty much the rule and not the exception, although with most of the newer carbs my experience has thus far been pretty good with auto chokes.
Surely there is a way to block open or otherwise limit the motion of the choke butterfly.....
Last edited by JMD; 11-13-2010 at 09:44 AM.
11-14-2010, 04:36 AM
#10
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Gun: no matter what you set the hosuing to the time the plate would spend half open because of the spring is minimal. don't quote me on numbers, that just the general idea. if you go fully rich the choke will be closed fully for 5 minutes, 20 secs opening and from there on fully open. if on lean it will be fully closed for a minute, opens in a fwe seconds and then stay fully open. I can't use the spring to control the setting where the plate ends up, only the duration of closed.
tcrote5516 and JMD: if there was a stop screw or anything I could use to avoid the plate being fully closed I'd use that before grimding the plate
But ya, fully agreed the other fella cut so much out that there's probably only the fast idle cam working for him
And black when starting is one story. in my case we're talking about dumping fuel like an airplane before an emergency landing ... :-)
I'll doublecheck again for any positive stops, maybe if I lenghten the rod it will avoid this thing to close fully. not sure.
Will be off next week in germany so will try next week.
But ya, good idea with the drilling. Might look better than cutting
tcrote5516 and JMD: if there was a stop screw or anything I could use to avoid the plate being fully closed I'd use that before grimding the plate
But ya, fully agreed the other fella cut so much out that there's probably only the fast idle cam working for him
And black when starting is one story. in my case we're talking about dumping fuel like an airplane before an emergency landing ... :-)
I'll doublecheck again for any positive stops, maybe if I lenghten the rod it will avoid this thing to close fully. not sure.
Will be off next week in germany so will try next week.
But ya, good idea with the drilling. Might look better than cutting