Electric Choke..... How to slow it down... [Archive] - Chevelle Tech

: Electric Choke..... How to slow it down...


sudolg
Jun 23rd, 07, 11:02 PM
The problem is that it opens up way too quick before the engine heats up. How do I slow it down? This is on my Demon Carb. I guess it heats the coils too quick and it opens up. There is no adjustment.

novaderrik
Jun 23rd, 07, 11:28 PM
turn it a bit to the "rich" side. i think to the right a bit.

MikeMalibu
Jun 23rd, 07, 11:35 PM
Loosen the three allen screws on the choke cap. Turn the cap clockwise or counter clockwise to get the response you want. I suggest taking off the air cleaner so that you can see the choke butterfly. Turn the key (no need to start the engine) and time the butterfly. Adjust and compare times until you're satisfied. I could never get an air cleaner to fit tight with the way the Demon choke linkage sticks outside the flange. Switch to Holley for that reason. Otherwise the Demon was excellent for my application.

658Chevy
Jun 24th, 07, 3:32 AM
I have a Road Demon and it does the same thing. I talked to their tech and he said that due to Demons not having any choke pull off, the intermediary between cold start and full warm is lacking. It makes for a rough and low idle for the first 5-10 minutes of driving, depending on outside temp. My right foot has become a replacement for the fast idle until the car warms up.

Other than that, the Road Demon is a great carb, although I know it gets dissed a lot. It starts up well and once the car is warm it performs beautifully with no hesitation and a lot of power.

sudolg
Jun 24th, 07, 8:36 AM
I have a Road Demon and it does the same thing. I talked to their tech and he said that due to Demons not having any choke pull off, the intermediary between cold start and full warm is lacking. It makes for a rough and low idle for the first 5-10 minutes of driving, depending on outside temp. My right foot has become a replacement for the fast idle until the car warms up.

Other than that, the Road Demon is a great carb, although I know it gets dissed a lot. It starts up well and once the car is warm it performs beautifully with no hesitation and a lot of power.

This is the exact problem. I have the choke set exactly where it needs to be in regard to the opening. Then there is no adjustment to slow it down. If I set it more rich, the engine doesn't like it and won't run right. The right foot idea works but when you have a manual trans, makes it a bit more difficult to step on the cluth, hit the brake and give it gas at the same time! I think I'm going to try to convert to a manual choke. This way I could shut it when its ready.

onovakind67
Jun 24th, 07, 9:41 AM
Chrysler used a small thermostatic switch and resistor on their electric chokes that was mounted on the intake manifold. When the engine is cold, the resistor is inserted in series with the choke element, and the reduction in current slows the operation of the choke. If the engine is already warm, the resistor is shunted by the switch and full current operates the choke heater. These were used on the mid-80's cars.

MikeMalibu
Jun 24th, 07, 11:30 AM
Greg,

Have you tried adjusting the fast idle screw that is behind the choke body ? Also, check to make sure the fast idle cam is not bent and works the fast idel screw correctly. I had to pull off the choke body to straighten the fast idle cam and choke linkage before my choke would work correctly. Came from the factory bent and out of position. Check out the BG web site for instructions on installing the choke. That can serve as a guide to remove and replace the choke body, fast idle cam and choke linkage. IMHO, the choke on the Demon is an after thought.

sudolg
Jun 24th, 07, 1:13 PM
Mike,

Yes indeed. I have my fast idle screw all the way. It has a nice fast idle at startup but shortly after when I hit the gas, it returns cause the choke opens up. I may use a resister to try to cut the voltage for the heck of it.

Tom Mobley
Jun 25th, 07, 2:09 AM
you need a 10 Ohm 10 watt resistor, usually referred to a "cement boat", look like white ceramic. just buy one, alligator clip it in, see how it works. if it's still too fast get a 15 watt, if it's too slow get a 5 watt. it's all about that rocket science thing.

somebody here found a really nice resistor that comes in an aluminum case with a tab, bolted it to the rear carb stud. very clean install. I've got a cement boat inside two pieces of shrink wrap.

sudolg
Jun 25th, 07, 7:52 AM
Thanks Tom. I am going to try that.

MikeMalibu
Jun 25th, 07, 11:14 AM
What Tom is referring to is an aluminum housed chassis mount resistor. Search www.Digikey.com, www.alliedelec.com, www.mouser.com.

If you can't rotate the choke body to get the correct timing, then lowering the voltage to the choke "heater" coil by inserting a series resistor makes sense, although I've never done that before.

I would think you need to adjust the resistance rather than the wattage of the resistor to change the timing of the choke heating.

onovakind67
Jun 25th, 07, 12:52 PM
Chrysler used a 10Ω 10W resistor in their setup, which is shunted by a thermo switch that closes at about 150.

sudolg
Jun 25th, 07, 6:13 PM
Actually, what about a switch that simply closes the circuit when it hits 150 degrees? Hmmm. Anything like this exist?

wildman926
Jun 25th, 07, 6:57 PM
I have the choke set exactly where it needs to be in regard to the opening.

There are multiple "steps" on the fast idle. You need to ensure that you are set on the last step, with the correct idle speed, with the correct amount of opening of the butterfly. That way, as your choke opens up, it gradually slows down in idle, so by the time it is warm enough to run without dying, the choke is completely off the fast idle cam. If you put it on the last "step", make sure you bend the choke rod to open the butterfly the correct amount, so that it is not "choked" off too much air for too long.

658Chevy
Jun 25th, 07, 7:03 PM
The tech guys at BG told me to try a resistor to slow down the choke opening. Before doing that, I tightened the choke so that it opened more slowly (the same effect), but apparently the engine didn't like that and bucked and bucked for 30 seconds or so until the choke finally opened. I suspect it would also buck with a resistor.

I was able to adjust the four idle screws so that the car had a nice, strong idle when warming up, negating the use of my right foot. But then ten minutes later, when the engine was fully warm, it ran like crap and I had to readjust the screws.

I think this is just the nature of this beast. I have an automatic, so my right foot-method doesn't bother me. I'm used to it as I also right-foot it when the A/C compressor kicks on. If you try the resistor, please post your results.

Also, the manual choke sounds like a good idea. Post about that if you try it.

Thanks.

onovakind67
Jun 25th, 07, 7:23 PM
Actually, what about a switch that simply closes the circuit when it hits 150 degrees? Hmmm. Anything like this exist?

Closes what circuit?

wildman926
Jun 25th, 07, 9:27 PM
Actually, what about a switch that simply closes the circuit when it hits 150 degrees? Hmmm. Anything like this exist?

What circuit? The current is what heats the spring to open the choke. You remove the current, spring gets cold, choke closes. The resister allows less current to flow, heating the spring slower.

onovakind67
Jun 25th, 07, 9:41 PM
I was just curious at to what circuit you would want to close at 150. The way the Chrysler circuit works is to reduce the current to the choke until the intake manifold is above about 150. At this temperature the switch closes and shunts the current around the resistor and allows the choke to pull off rapidly. If you shut the car off just long enough for the choke to close, it will openly quicker the second time around because the intake is already warm.

69-CHVL
Jun 28th, 07, 3:43 PM
Funny - my choke opens way too fast also, I rotated the housing CCW ALOT but it still open fast. And the thing is, I have like 6 or 7 volts going to it b/c I'm getting power from the back of the alternator. Wonder if 12v would make it even faster?

sudolg
Jun 28th, 07, 4:48 PM
I just meant that the current would not hit the choke until the engine reached 150 degrees. Then it would open up. I'm just afraid that it would still be too fast even if it sent a lower voltage.