Rochester electric choke conversion

[Buzzman]

Wiring question - I'm looking to convert the choke on my '79 from climatic/hot-air to electric.

Seems straightforward on the carb end, but I'm a novice when it comes to wiring. I'd like to wire it directly to the fuse box - has anyone done this and if so, could you point out where exactly on the box I want to be looking?

Finally - and here's where the novice really comes out - how does one insert a wire into the fuse box, exactly? Is there a male plug I can get? Thanks!

[gmachinz]

I build replacement engine harnesses for these trucks so I can help you out here.

If you are viewing the engine part of the bulkhead straight-on, the electric choke wire is the lower right cavity and GM used a light blue 14ga wire. This serves as an IGN source for the electric choke. Here is a pic showing the correct GM choke connector, the correct terminal for it and the 56-series Packard male terminal you need for the bulkhead connector.....

[Buzzman]

Thanks for the reply! Will my '79 have this cavity even though it was not equipped with elec. choke from the factory? Thanks.

[gmachinz]

Yes....its an IGN hot source-GM used this for the electric choke where equipped.

[c3006]

I believe the light blue wire is hooked in conjunction with the oil pressure sending unit and is only hot when oil pressure is present.

[gmachinz]

If the truck had a dual wire oil switch, the IGN runs through it and then to the choke. However, if not equipped or if only the electric choke is desired, you can run it direct from that cavity. The reason GM had it running through the oil circuit is so that with key on and engine off it wouldn't energize the choke coil when it wasn't needed, saving battery juice. But again, whichever way works for you.

[Just call me Sean]

The pressure switch keeps the choke from opening when the truck isn't running. If you sit there with the key on the choke will open without the pressure switch, then when you go to start it the choke won't work because it already opened.

[gmachinz]

Yes, that's what I said. But, there really shouldn't be any circumstances where a person would need the key on for that length of time-thats what the ACC is for. On older trucks without an ACC on the column, you'd see a dual wire oil pressure switch unless you had the hot air choke-in that case, the bulkhead cavity is empty.

[Just call me Sean]

Originally Posted by gmachinz

Yes, that's what I said. But, there really shouldn't be any circumstances where a person would need the key on for that length of time-thats what the ACC is for. On older trucks without an ACC on the column, you'd see a dual wire oil pressure switch unless you had the hot air choke-in that case, the bulkhead cavity is empty.

No, you said it was to save battery juice which is incorrect. It's to allow the choke to work when needed.

[gmachinz]

The reason GM had it running through the oil circuit is so that with key on and engine off it wouldn't energize the choke coil when it wasn't needed, saving battery juice.

Dude, we are saying the same thing here-I simply added that obviously if for some odd reason one were to leave the key "on" among other things to cause a parasitic drain, the choke coil is one of them.

Regardless, to put it simply you can use the cavity as your electric choke circuit since its an IGN source-just don't leave the key on needlessly. Besides, even with the key left on for a few minutes with a hot engine off, the choke will remain open-and if the engine is cold, it still takes a few minutes for the choke to open. So, I would say if you run the choke off an IGN source, be aware of having the key on with engine off.

[Just call me Sean]

Just trying to be clear for all to understand. As a person that builds wiring harnesses I find it unusual that somebody else mentioned the switch first instead of you. The factory doesn't usually put unnecessary things on vehicles, so I would have to say it's important.

[gmachinz]

Originally Posted by Buzzman

Wiring question - I'm looking to convert the choke on my '79 from climatic/hot-air to electric.

Seems straightforward on the carb end, but I'm a novice when it comes to wiring. I'd like to wire it directly to the fuse box - has anyone done this and if so, could you point out where exactly on the box I want to be looking?

Finally - and here's where the novice really comes out - how does one insert a wire into the fuse box, exactly? Is there a male plug I can get? Thanks!

Ok...I understand your concern BUT-refer to the original post-hot air to electric choke, he doesn't have the choke circuit running through his oil switch, so he asked where in the fusebox to run it.

[Just call me Sean]

Then if he wants it correct he can get the feed where you said and get the connector, switch and tee and do it right. I just like to offer the right way to do it in case one doesn't know, but your way will work almost correctly.

[MountainGoat1966]

Okay, since I live in a cold climate (in the winter only) I need to get in on this thread.
The 83 C20 I recently bought has a Q-jet with no wire hooked up to the choke. I see the connector on the carb where power is applied.
The engine has the single wire oil pressure sender, so I would need to use the blue wire thingy.
The wire might be the one I see hanging loose on the engine. (see pic 1).
I haven't tested it yet to see if it has power when the key is on.
Also I discovered a strange connector laying loose next to it, (see pic 2).
Anybody know what it does and if it's related to anything important I need ?
Also, the two green wires the PO had just wrapped out of the way, what do they do?

[Just call me Sean]

Not sure what that connector is, the oil pressure switch is round with two wires. Can't tell what the other wires are for but the a/c compressor does have a green wire to it, but so does the temperature gauge sender.

[gmachinz]

You should have (2) oil switches-one for the gauge (typically in the engine block above the oil filter pad, tan in color) and a dual spade switch on the back of the intake. The switch on the intake (for factory V8's) should have a pink w/white stripe coming from the bulkhead connector on one side of the connector-this is your choke/fuse lead, and the other side of the connector should have 2 dk blue leads-one goes to your factory choke, the other goes to your bulkhead connector. I stock the connectors/terminals so PM me if you can't find them.

[Buzzman]

Update - got the choke on fine yesterday, wired it to the fuse box, 12V key-on power. Everything looks good...
This morning (45 F), fired up fine, but after about 3 min. warm-up in the driveway and a 5 min. drive to work, it never dropped out of fast idle. I didn't touch the fast idle cam yesterday when I installed the choke - should I have payed closer attention to that? I backed the fast idle screw back a quarter turn so we'll se how it goes tomorrow.
Any tips? Thanks!

[johnwaynejeep]

no real help here, just opinion

Go mechanical choke. It's easier to adjust and always where it needs to be...right where you put it.

[Buzzman]

Haha - thanks for the advice, but I'm not that fed up yet. Damned electric one hasn't been even on there 24 hours... gotta give it a try.

[geezer#99]

Lean it down.
Rotate the cap cw for leaner (kicks off sooner).
I adjust mine lean in the summer and richer ccw in the winter.

[Buzzman]

Thanks, geezer#99, I'll try that tonight and see how it behaves in the morning.

[SkinnyG]

Make sure you didn't put in the gasket between the old hot air choke thingie and the housing - you need a ground for it to work, and the gasket insulates from ground.

[Dead Parrot]

Green wires in that area are usually either AC related or a temp sender wire. If AC could either be for the compressor or the idle solenoid. The temp sender usually goes down on the drivers side head. Even if it doesn't now have AC, it is possible the PO removed it when they replaced the engine.