Electric Choke vs. Divorced Choke?

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Nov 15, 2009 | 06:06 PM

Two Red Vettes

Thread Starter

Burning Brakes

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Electric Choke vs. Divorced Choke?

I have a stock '71 350/270HP that needs a carb rebuild. It presently has a divorced choke (with bi-metallic spring) that works fine and I have no complaints.

Is there any advantage to converting to an electric choke during the carb rebuild?

Which style do you prefer, and why?

Thanks

Nov 15, 2009 | 10:06 PM

mds3013

Melting Slicks

Joined: Mar 2009

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No real benefit either way if working properly.I say stick with what came on car. mds...

Nov 15, 2009 | 11:04 PM

7T1vette

Team Owner

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From: Crossville TN

No advantage to an electric choke...IF your heat riser valve is working properly and the heat passage under the carb [intake manifold] is not clogged up. Set the choke up per instructions in the "Fuel" section of the Chevrolet Chassis Service Manual.

Nov 15, 2009 | 11:10 PM

Two Red Vettes

Thread Starter

Burning Brakes

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Quote:

Originally Posted by 7T1vette

Suppose I chose to block off the heat passage (as some Folks do), would the divorced choke no longer work properly?

Thanks

Nov 16, 2009 | 09:13 AM

jnb5101

Le Mans Master

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From: charlotte north carolina

not all q jets have the mounting areas for an electric choke.

Nov 16, 2009 | 09:19 AM

Mike Ward

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Quote:

Originally Posted by drspencer

Suppose I chose to block off the heat passage (as some Folks do), would the divorced choke no longer work properly?

Thanks

It would still work, but take quite a while to open fully.

Nov 16, 2009 | 09:38 AM

7T1vette

Team Owner

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From: Crossville TN

Right. It would take longer to open. If you don't drive the car in cold weather very much, it won't make a lot of difference. Out of curiosity, why would you block off the intake heat channel?

Nov 16, 2009 | 03:53 PM

Two Red Vettes

Thread Starter

Burning Brakes

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Quote:

Originally Posted by 7T1vette

Right. It would take longer to open. If you don't drive the car in cold weather very much, it won't make a lot of difference. Out of curiosity, why would you block off the intake heat channel?

Some people claim to get better performance. I'm new, so I'm just gathering information.

Thanks

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Nov 16, 2009 | 04:02 PM

MelWff

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You cannt to the best of my knowledge easily convert a divored choke quadrajet to an electric choke. If the only change you are making is blocking off the crossover, it's probably not worth it.

Nov 16, 2009 | 06:53 PM

#10

7T1vette

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From: Crossville TN

The carb needs to be heated to function efficiently. I just don't know whether normal engine heat is adequate to accomplish that...or not. I've left mine open, even though the valve is out of the heat riser, and kept the insulator under the carb. If someone can tell me that it's better to block the crossover, then remove the insulator, I'm interested in hearing the logic.

Nov 16, 2009 | 11:08 PM

#11

Two Red Vettes

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Burning Brakes

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Quote:

Originally Posted by MelWff

You cannt to the best of my knowledge easily convert a divored choke quadrajet to an electric choke. If the only change you are making is blocking off the crossover, it's probably not worth it.

If I bought a rebuilt Q-Jet with an electric choke, are there any issues mating it to a manifold that originally had a divorced choke?

Where would I get the 12V to operate the new electric choke?

Thanks

Nov 17, 2009 | 01:07 AM

#12

nitronick

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Quote:

Originally Posted by drspencer

You shouldn't have any clearance issues provided you pull the old spring off the manifold.
You will need to find a 12 volt source that is hot when the key is turned on. A usual suspect has always been the white wire in the windshield wiper loom.

I sent you a PM....

Nov 17, 2009 | 01:29 AM

#13

Peterbuilt

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From: mount holly NC

2025 c3 ('74-'82) of the Year Finalist - Unmodified

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Quote:

Originally Posted by drspencer

If your 71 has the original carb with a divorced choke there is no way to convert it to an electric choke.
Lars Grimsrud published a paper on how to properly adjust a divorced choke, I can't find the link but I have a copy, if you need it PM me your email. PG.

Nov 17, 2009 | 08:03 AM

#14

Two Red Vettes

Thread Starter

Burning Brakes

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Quote:

Originally Posted by petes74ttop

Can I replace it with a Q-Jet that has an electric choke?

Thanks

Nov 17, 2009 | 08:12 AM

#15

7T1vette

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From: Crossville TN

pete....
The choke set-up procedure is laid out in the Chevy Chassis Service Manual in the "Fuel System" section.

drspencer...
Yes you can, but will the carb be set up properly for your engine?

Nov 17, 2009 | 10:29 AM

#16

highschool67

Drifting

Joined: Oct 2004

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From: Coralville Iowa

I swapped out a divorce choke qjet for a holley spreadbore electric choke unit in my 66. It starts on the first or second crank every time without my foot on the gas. I like the electric choke myself. No need for adjustment. It is closed at start-up and timed with the bimetal spring for full open. I bought an electric choke conversion for the qjet on my 72. You have to pump the pedal a couple of times to get it to start with a warmed up engine. I'm hoping the conversion will help it start like my 66.
The down side......
It doesn't look stock.

BTW The conversion kit is only available for qjets with exhaust manifold heat choke. ( round , enclosed, choke housing with 3 retaining screws for adjustment)

Last edited by highschool67; Nov 17, 2009 at 10:33 AM.

Nov 17, 2009 | 10:50 AM

#17

weimer20

Burning Brakes

Joined: May 2007

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From: Ventura California

Quote:

Originally Posted by 7T1vette

Why does a carb need to be heated to function efficiently? My understanding is that a colder / therefore denser intake charge is better for power. Cold cans have been around forever to help accomplish this. "Air gap" manifolds have been designed to keep the carb and runners as far removed from lifter valley heat as long as possible before entering the head and cylinders. Am I missing something?

Nov 17, 2009 | 10:50 AM

#18

Mike Ward

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Engines that need excessive cranking to start after a few days rest have issues unrelated to the choke mechanism.

Nov 17, 2009 | 10:07 PM

#19

Peterbuilt

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From: mount holly NC

2025 c3 ('74-'82) of the Year Finalist - Unmodified

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Quote:

Originally Posted by drspencer

Can I replace it with a Q-Jet that has an electric choke?

Thanks

You'll need the type of carb on the right, I think they are from 75 and up.

Nov 17, 2009 | 10:15 PM

#20

71406

Burning Brakes

Joined: Mar 1999

Posts: 1,047

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From: CA

You can buy an electric choke conversion for you car at Carburator's Unlimited. http://www.carburetion.com/quadrajet.asp

Scroll down on this page and look at conversion kit CU445

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