Holley 650 Electric Choke Help

-
Chained_360

Chained_360

Delusional Member
FABO Gold Member
Joined
Nov 11, 2015
Messages
562
Reaction score
332
Location
Indianapolis, IN
Hi everyone,

I'm having some trouble with the electric choke on my Holley 650 vacuum secondary, electric choke. It's installed on my 1978 360 in my '68 Barracuda, and it's a very mild engine. RV cam, headers, dual plane intake, the car idles dead smooth when warm. After having it disconnected for two years due to a hokey wiring job (thanks, past me!) I finally put it back together in a more acceptable way and was reminded why I was okay with disconnecting it in the first place.

When I cold start the car in the morning, with the choke closed and the fast idle cam on, it runs stinky rich and very rough. Like, black smoke out the tailpipe rich. It also tries to idle at about 2,000+ rpm. If I go and manually open the choke just a little bit (it seems like there is too much play, should I be able to do this?) the idle smooths out a little and the RPM picks up. After idling for about a minute it comes down to an acceptable and more smooth fast idle, and once it's warmed up it runs just fine. What's going on here? I thought even with the choke plate fully closed it should run smooth when cold.

I've taken a video of this predicament, here is the link:
I fussed with it yesterday, I backed the fast idle screw WAY off and also advanced the choke a little too much, so I'll fix that. But still, on first startup you can see the black smoke coming out of the exhaust. AND this was filmed on a 29 degree (Fahrenheit) morning in Anchorage, Alaska. What am I doing wrong? The carburetor is tuned just fine for warm/normal operation, it idles nicely and doesn't stumble or stutter anywhere during normal or aggressive driving. Thoughts?
 
Here's what I've learned about how an automatic choke is supposed to work.
You'll have to investigate the carb you've got has all the features.

Initial Choke position: This is where the choke plate sits when the engine off. It is the maximum restriction to the airflow.
Qualified Choke position: Plate position immediately upon starting.
* It's opened by manifold vacuum.
* The amount it opens is usually adjusted by increasing or decreasing the spring force on a vacuum diaphram.
* Usually the linkage is such that the qualified position is based on the initial position, not independent.
* It does not effect the throttle fast idle position.

Fast idle cam has two or three steps. In warmer weather the cam's linkage to the choke should rotate it off the upper step(s) pretty quick.
* Engine cold, cold weather the initial choke position brings the fast idle cam to so the throttle is resting on the upper step.
* Fast idle speed is usually adjusted on the second step.

Some carbs have internal vacuum source connection to the choke. They may not have a means of adjusting the qualified choke position if its internally connected. Some carbs don't have any vacuum source. I think the only solution for them is set the choke for the running position and use pump shot (working the throttle) to get it rich enough to fire off.

Unloader: Some mechanical means to hold the choke open when the throttle is close to wide open. A means to help clear a flooded intake if its held open.
 
Chained_360 said:
Hi everyone,

I'm having some trouble with the electric choke on my Holley 650 vacuum secondary, electric choke. It's installed on my 1978 360 in my '68 Barracuda, and it's a very mild engine. RV cam, headers, dual plane intake, the car idles dead smooth when warm. After having it disconnected for two years due to a hokey wiring job (thanks, past me!) I finally put it back together in a more acceptable way and was reminded why I was okay with disconnecting it in the first place.

When I cold start the car in the morning, with the choke closed and the fast idle cam on, it runs stinky rich and very rough. Like, black smoke out the tailpipe rich. It also tries to idle at about 2,000+ rpm. If I go and manually open the choke just a little bit (it seems like there is too much play, should I be able to do this?) the idle smooths out a little and the RPM picks up. After idling for about a minute it comes down to an acceptable and more smooth fast idle, and once it's warmed up it runs just fine. What's going on here? I thought even with the choke plate fully closed it should run smooth when cold.

I've taken a video of this predicament, here is the link:
I fussed with it yesterday, I backed the fast idle screw WAY off and also advanced the choke a little too much, so I'll fix that. But still, on first startup you can see the black smoke coming out of the exhaust. AND this was filmed on a 29 degree (Fahrenheit) morning in Anchorage, Alaska. What am I doing wrong? The carburetor is tuned just fine for warm/normal operation, it idles nicely and doesn't stumble or stutter anywhere during normal or aggressive driving. Thoughts?
Click to expand...



Where is the positive lead for the choke hooked up??? You need a keyed to the ignition on 12 volt source...

From the video, it looks like you have it hooked up to the coil ---> That's a no-no - the coil positive has only 6 volts....

Hook it up to the ballast resistor input side... To find the input side of the ballast, disconnect the wires from both sides of the ballast resistor, then take a test light with the clamp end hooked to the battery negative, then probe each of the ballast resistor wires that you disconnected for power with the key in the on position... Whichever wire makes the test light go on, is the input positive side of the ballast, that is what you want to hook up to... I use a flat blade piggyback terminal and stack the two, but you can just wire them together if you wish...


After you get the proper connections for the choke, then you will need to reset the fast idle choke screw and put the electric choke to the center of the adjustment and go from there... A good way to get a ball park for the adjustment of the pod, is to get the engine warmed up and rotate the pod until the top plate for the choke is just fully open... Then try a few more cold starts and see where you are at and adjust from there...
 
Here's how I stack the piggyback terminals. This way I can remove/disconnect one easily and not have to do any more modifications to the wiring...



DSC03673 B.JPG


Here I have it circled in red...

DSC03673 B2.jpg



Here's with just my choke piggyback and the others removed...

DSC03675 B.JPG



Here it is circled in red....

DSC03675 B2.jpg



Here it shows how they stack together...

DSC03676 B.JPG



Here they are circled in red...

DSC03676 B2.jpg



Here's to show how they stack...

DSC03679 B.JPG



Circled in red...

DSC03679 B2.jpg



Here's what a piggy back terminal looks like:

Piggy Back Terminal.png
 
krazykuda said:
Where is the positive lead for the choke hooked up??? You need a keyed to the ignition on 12 volt source...

From the video, it looks like you have it hooked up to the coil ---> That's a no-no - the coil positive has only 6 volts....

Hook it up to the ballast resistor input side... To find the input side of the ballast, disconnect the wires from both sides of the ballast resistor, then take a test light with the clamp end hooked to the battery negative, then probe each of the ballast resistor wires that you disconnected for power with the key in the on position... Whichever wire makes the test light go on, is the input positive side of the ballast, that is what you want to hook up to... I use a flat blade piggyback terminal and stack the two, but you can just wire them together if you wish...


After you get the proper connections for the choke, then you will need to reset the fast idle choke screw and put the electric choke to the center of the adjustment and go from there... A good way to get a ball park for the adjustment of the pod, is to get the engine warmed up and rotate the pod until the top plate for the choke is just fully open... Then try a few more cold starts and see where you are at and adjust from there...
Click to expand...
The choke is on battery power through a relay triggered by switched ignition. I just have the wire tucked in with the factory harness on the firewall. I'll have to reset the choke settings and start over. I didn't know that coil output was 6 volts though!
 
Just out of curiosity, has the carb back fired & possibly blown the power valve? That would contribute to the rough & rich idle. Just a thought & my.02.
 
You must log in or register to reply here.
-

Back
Top