Edelbrock Electric Choke Issues?

[savatreatabvr]

Just installed a Edelbrock 1407 on my mid 70's 454 and it runs great! My only issue is when I hooked up a switched 12v wire to the choke it didn't really do anything but if I slowly close the choke flap with the engine fully warmed up it raises the idle and seems to run better and when I flip the choke flap fully open, (vertical), it idles lower and runs rougher! It's like it runs better when the choke is on or partially on! When I manually close the choke flap when fully warmed up shouldn't it automatically open back up with 12v applied to the choke?

[INSIDIOUS '86]

It should be closed when the engine is off and when the engine is running it should heat the spring inside slowly and will open the choke up fully when the engin is warm. If everything is adjusted right
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[wilkin250r]

I'm not sure I understand what you're "asking". You've got a question about the operation of the choke, but you also seem to be confused about why your engine seems to run better with the choke on. My specialty is the operation of the choke, so let's start there.

The electric choke isn't like a manual choke, with no voltage being "closed" and 12V being "open". Applying 12V to the choke causes an internal spring to slowly warm up, but it's not instant. While the spring is cold, the choke is closed. As it warms up, the choke will slowly open.

This means that you start your car, the choke is closed while your engine is first running and hasn't fully warmed up yet. Ideally, the choke warms up along with your engine and slowly opens up as the engine warms up. It definitely doesn't snap open and closed with 12V.

This also works in reverse. If you shut off your car for five minutes to gas it up, your engine isn't cold. It doesn't need the choke to start now, and luckily, that internal coil inside the choke is still warm, too, so the choke is still open.

As far as your other issue, why your truck seems to be running better with the choke closed even when it's warm, I can't really help you. Possibly a vacuum leak.

[piecesparts]

To set that electric choke, loosen the three screws on the bakellite housing and when the engine and the choke is cold, turn the bakelight housing until you see the choke plate move towards the closed position. Now tightnen the screws and then adjust the the idle speed screw to allow for t he choke to set the idle at about 1200 RPM when it is triggered by cold weather.

You may have to actually wait until it is colder outside to get it set right. Make sure that your 12 volt source is only on when the igntion switch is on.

[savatreatabvr]

Excellent info, thanks for spending the time to explain it! I understand the electric choke basics, I know I need a switched 12v ignition source, I know the choke is closed when cold and open when warmed up so let's say (just for reference), Mr. Bill has an engine that runs perfectly, when it's fully warmed up slowly closing the choke plate will kill the engine, not raise the idle and smooth out! You mentioned a vacuum leak, I've checked everything and no leak but I swear I hear one while driving, how do I find that?

Originally Posted by wilkin250r

I'm not sure I understand what you're "asking". You've got a question about the operation of the choke, but you also seem to be confused about why your engine seems to run better with the choke on. My specialty is the operation of the choke, so let's start there.

The electric choke isn't like a manual choke, with no voltage being "closed" and 12V being "open". Applying 12V to the choke causes an internal spring to slowly warm up, but it's not instant. While the spring is cold, the choke is closed. As it warms up, the choke will slowly open.

This means that you start your car, the choke is closed while your engine is first running and hasn't fully warmed up yet. Ideally, the choke warms up along with your engine and slowly opens up as the engine warms up. It definitely doesn't snap open and closed with 12V.

This also works in reverse. If you shut off your car for five minutes to gas it up, your engine isn't cold. It doesn't need the choke to start now, and luckily, that internal coil inside the choke is still warm, too, so the choke is still open.

As far as your other issue, why your truck seems to be running better with the choke closed even when it's warm, I can't really help you. Possibly a vacuum leak.

[INSIDIOUS '86]

Originally Posted by savatreatabvr

Excellent info, thanks for spending the time to explain it! I understand the electric choke basics, I know I need a switched 12v ignition source, I know the choke is closed when cold and open when warmed up so let's say (just for reference), Mr. Bill has an engine that runs perfectly, when it's fully warmed up slowly closing the choke plate will kill the engine, not raise the idle and smooth out! You mentioned a vacuum leak, I've checked everything and no leak but I swear I hear one while driving, how do I find that?

Ask your carb adapter if its behaving.

Carb cleaner sprayed around it will tell if there is a leak
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[gchemist]

Edelbrocks have a problem with electric chokes. It opens up to fast!! I have to adjust mine twice a year. Once for hot weather. Once for cold weather. I've been thinking of adding a resistor in line so it opens slower. If you run a high rise aluminum intake, it takes even longer for the carb to warm up.

[savatreatabvr]

Yeah, I wasn't supposed to use the Mr. Gasket open adapter and use the Edelbrock 2696 but the 2696 was $40 more and was a special order, the Mr. Gasket was readily available! Don't get me wrong, the 454 still runs better with much more response and fuel economy but I think I'll go ahead a order the 2696, might as well do it right, right?

Originally Posted by INSIDIOUS '86

Ask your carb adapter if its behaving.

Carb cleaner sprayed around it will tell if there is a leak
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[wilkin250r]

I say vacuum leak because your carburetor uses a mixture of two signals to deliver fuel to the engine, vacuum and air speed. At idle, air speed is very low, vacuum is very high, so vacuum is the main signal.

Closing the choke will deliver more fuel. If that makes your engine run better, it leads me to believe your carburetor isn't delivering enough fuel normally. Since we've already established that the vacuum level is the main signal the carburetor uses at idle, then it sounds like vacuum level is low.

Have you hooked up a vacuum gauge?

[savatreatabvr]

Yeah, my vacuum gauge reads a steady 17hg so I've got good vacuum!


I do hear what I think is a vacuum leak while driving at steady speeds, not all the time though! The funny thing is I can't find a leak at idle, even after spraying carb cleaner around the intake and carb! Now when I first start it in the morning it acts like it's flooded (running rough) and takes a few minutes to smooth out and idle but after it's warmed up it runs fine! So how can it be flooding over night?

Originally Posted by wilkin250r

I say vacuum leak because your carburetor uses a mixture of two signals to deliver fuel to the engine, vacuum and air speed. At idle, air speed is very low, vacuum is very high, so vacuum is the main signal.

Closing the choke will deliver more fuel. If that makes your engine run better, it leads me to believe your carburetor isn't delivering enough fuel normally. Since we've already established that the vacuum level is the main signal the carburetor uses at idle, then it sounds like vacuum level is low.

Have you hooked up a vacuum gauge?

[wilkin250r]

Hmm. Let's check a few more areas for vacuum leaks before we rule it out. It doesn't always have to be at the carb itself, it could be in a vacuum line somewhere else.

17hg is a decent vacuum signal, but it's not great. Try opening the throttle just a hair, just a little bit above idle. If you're idling at 800rpm, crack the throttle until you're around 1100 rpm. If the vacuum doesn't increase to over 20hg, then you might have a problem in your throttled vacuum port, which most likely is hooked to your vacuum advance on the distributor. That particular vacuum port is just ABOVE the throttle plate, so you won't see anything there at idle.

If the vacuum DOES increase to over 20hg, try revving the engine to over 2000 rpm, and letting the throttle snap closed. When the throttle snaps closed, you should get a really high vacuum reading, let me know roughly what that is.

[GuyO]

Um, generally as an engine warms it needs to be leaned out. By adding choke (decreasing air) thereby enriching your mixture you may find that your choke finds the right balance of air-fuel based on your air density, ambient temperature and moisture content at that particular time period. Also gas is not consistent and contains Ethanol. Its possible your choke is OK, its the outside air or gas and your engine is telling you whats going on in the environment it operates in. My thoughts, G.

[jon75]

I have an Edelbrock 1406 with electric choke. The reason your engine is running well with the choke partially closed is because your engine is starving for fuel when the choke is fully open. The Edelbrock carbs are set up more-or-less for SBC's. You need to adjust your fuel feed screws in the front of the carb and that will take care of your issues.

[GuyO]

Jon75 makes a good point. Sometimes the carb idle is leaned out too much - even when shipped new. It is the easiest thing to do first is adjust idle mixture. Also last year after running on the dyno I had to re-jet a 1406 for a brand new 327 because it was still running too lean during break-in. I'd go after the idle mixture first, choke adjustment second then fuel source then rejet as a last resort providing good fuel delivery from the pump.

[frankyjoet]

jon, have 1406 4 bl with electric choke. also have an rv cam. the engine lopes a little at idle. do i adjust both idle screws, fuel and air. i have no problems with the choke in warm weather, live in Az. But when the weather gets colder in the A.m., the engine stalls. Also have been testing 12v for power to choke with key on and running. the test lite shows no power. the grnd wire is attached to the choke housing. thanks in advance for any help. 73truck