For those of you that have already converted over to an electric choke, where did you pick up 12 volts from an ignition keyed source? The distributor does not provide 12volts because of the resistance wire. I thought I read that electric chokes pull about 3.5 amps and perhaps I could run a wire to the alternator with a 5 or 10 amp fuse. Suggestions?

What kind of ignition do you have? Points or HEI?

If you have HEI then power it off of the same +12 connection as distributor.

If you have a points distributor, there is a dropping resistance wire in series with the coil and you need to power the choke just before the resistance wire.

There is a connection between the 20 ga. resistance wire (pink / black) and the regular wire (18 ga. black) on top the engine. Follow the resistance wire from the coil wire back toward the front of the engine and find where it connects to a black wire that continues on to the terminal BK under the passenger hood. Attach your new choke wire to that junction of the resistance wire and the regular wire. It sounds more difficult than it really is.


Here is a thread from last January where we were discussing this connection for a different reason.

http://www.gmc.mybirdfeeder.net/GMCforum/index.php?t=tree&goto=351835&rid=12&srch=resistance+wire#page_top

I do not like the isolator connection solution because if the alternator ever quits you can not drive on the battery, or boost switch using the Onan. I doubt you will even make it to the next interstate exit before the choke closes and kills the engine.

The choke on mine draws about 1.5 amps

Thank you for your response. I have points but will be converting to Dick Paterson Pertronix distributor within the month. I was having a quadrajet issue of flooding after a local carb rebuild but couldn't seem to get it corrected by the carb rebuilder. Dick says it's a float/needle/seat problem but after replacing quadrajet, I put a straight edge across bottom of the original carb and the base is warped - high in center. Tearing it down today to check the rest of the carb. Meanwhile, replacement carb (reman by Dick) has an electric choke that needs 12 volts.

Matt, when they install that Pertronix mod, do they eliminate the ignition resistor (nichrome wire)?? I do not think so. If the nichrome wire is still in use, then then what I said about finding that connection still should apply Petronix or not.

There is a third not mentioned above, that is if you buy the kit that has a thermal switch that you can mount on the thermostat housing. Then it powers the choke heater when the engine gets hot. I have never put one on a GMC, but used these other places and they can be set up to work right.

Ed,

There is a third not mentioned above, that is if you buy the kit that has a thermal switch that you can mount on the thermostat housing. Then it powers the choke heater when the engine gets hot. I have never put one on a GMC, but used these other places and they can be set up to work right.

Matt

I used one of those for awhile after my choke stove tube broke off and before I went to EFI.

Ed,
Side note....
If you replace the points with A Pertronix 1181LS, that is a very reliable mod. (You can put the removed points and condenser in a jar and carry then as spares if you are paranoid.)

Matt

Quote:

I used one of those for awhile after my choke stove tube broke off and before I went to EFI.

Which EFI unit did you install? Holley has a Quadrajet EFI that just bolts on in place of the carb. However, it will require dropping the tanks and installing a return line plus plumbing the electric pump, filters and lines. It also requires blocking the exhaust crossover on the intake but I plan on replacing the cast iron intake with the "cast for GMC" aluminum intake without the heat crossover exhaust ports.

Can you throw a part number for that heat driven choke?
Thanks

Tilerpep wrote on Mon, 30 March 2020 06:32

Can you throw a part number for that heat driven choke?
Thanks

Mike's Carburetors - CU1121 Electric Choke Conversion Kit