Author Topic: Ignition switched feed for choke?  (Read 845 times)

Offline Chevygold

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Ignition switched feed for choke?
« on: October 09, 2019, 07:28:37 AM »
Im fitting an auto choke to my Edelbrock carb in my 76 Cheyenne with 350 any suggestions where I can get an ignition switched supply under the hood?
Graham


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Offline Irish_Alley

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Re: Ignition switched feed for choke?
« Reply #1 on: October 09, 2019, 11:52:33 AM »
Oem setup would be from the oil pressure switch.
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Offline Chevygold

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Re: Ignition switched feed for choke?
« Reply #2 on: October 09, 2019, 03:01:11 PM »
Thanks Irish sounds logical although I haven't found one yet, still looking for the oil gauge pipe as well, there's a pressure sender for an electrical gauge but dash gauge is still original.
Still quite a long list of things to do yet, at least all the lights seem to work.
Graham

Offline bd

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Re: Ignition switched feed for choke?
« Reply #3 on: October 09, 2019, 03:32:26 PM »
The typical oil pressure switch for electric choke power is SPST-NO, non-grounding and has two prongs.



It is available in 1/8" NPT and 1/4" NPT thread.  Which switch configuration you choose depends on whether you want to mount it in the rear China wall of the engine adjacent to the distributor (1/8" pipe) or down by the oil filter (1/4" pipe).  You can piggyback power from the pink B+ wire that feeds the HEI distributor.

For information on the function of the factory electric choke, see GM electric choke operation for Q-jet carbs.
Rich
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Offline blazer74

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Ignition switched feed for choke?
« Reply #4 on: October 10, 2019, 02:14:41 AM »
I put the switch up behind the Alternator in the 1/8 port there on the block in my 74 K5
Ran a wire from an aux fuse panel I installed in the cab next to the factory fuse panel and is dedicated for the choke..
Wiper motor has an ignition hot wire that is accessible also.
« Last Edit: October 10, 2019, 11:21:20 AM by blazer74 »

Offline 75gmck25

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Re: Ignition switched feed for choke?
« Reply #5 on: October 10, 2019, 05:08:12 AM »
The wiring harness on my '75 had an ignition-switched brown wire exiting the loom near the brake booster, and it was used for a factory installed dual battery relay mounted on the driver's side fenderwell.  The relay and battery are long gone, so I extended the wire and used it for an electric choke.  I don't know if that extra wire is always installed, or if it was only there if you had dual batteries.

Bruce

Offline VileZambonie

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Re: Ignition switched feed for choke?
« Reply #6 on: October 10, 2019, 06:04:08 AM »
You do not want the choke to come on in the accessory position, only when the engine is running, which is why we use the oil pressure switch as an easy way to get that engine running signal. The port is on the driver's side of the distributor. Look over in that area for an existing switch and brass fitting. 1/8 NPT tee can be purchased at any hardware store or you can find tons of them on eBay if you don't want the hardware store look. I keep a bin or assorted 1/8"-NPT fittings, adapters and tee blocks for when I do swaps.
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Offline Chevygold

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Re: Ignition switched feed for choke?
« Reply #7 on: October 17, 2019, 01:22:26 PM »
Took my carb off to install the choke kit then refitted it today, all went well until I went in search of an ignition switched supply, when I looked for the oil pressure switch where the oil pressure take off point is at the rear side of the block on the drivers side of the block all I found was what looked like a VDO pressure sender with nothing connected.
I think my truck should have a conventional oil pressure gauge(not electrical) but so far I haven't located the pipe that feeds it, I'll need to pop the gauges out to see if it's tucked up behind, can't see an oil pipe poking out of the bulkhead anywhere, where would it be?
When I see all the wires dangling all around this truck it amazes me how many things actually work!
So far all that seems to be MIA are the wipers and the heater fans, not too bothered about the fans but with  the amount of rain we've been getting lately I'll have to get the wipers working!
Thanks

Offline Chevygold

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Re: Ignition switched feed for choke?
« Reply #8 on: October 18, 2019, 04:07:22 PM »
Found the wire to the original auto choke and have ordered a 2 pin oil pressure switch so hopefully I can find the original wire to the switch amongst the loose wires I think it should be dark blue?
Graham

Offline Chevygold

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Re: Ignition switched feed for choke?
« Reply #9 on: October 21, 2019, 03:45:36 PM »
Did a bit more checking tonight and found the choke wire was connected to the accessory terminal in the fuse block so will either move it to the ign terminal or try to find the original choke feed and go through the oil pressure switch which I should get tomorrow.
Found why the wipers don't work, fuse missing! also found Bubba had been in the fuse block and fitted a home made "fuse" in place of the 20A fuse on the right of the 3 which I think only feeds the cig lighter?
I'll get some fuses and see if I can get the wipers working, hope the motor's good.
Small steps but making progress.
Graham

Offline bd

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Re: Ignition switched feed for choke?
« Reply #10 on: October 21, 2019, 03:55:14 PM »
The original wire color feeding power to the electric choke via the OPS is pink with a white stripe, protected by the Choke fuse.  Are you going to restore function of the choke warning lamp?
Rich
It's difficult to know just how much you don't know until you know it.
In other words... if people learn by making mistakes, by now I should know just about everything!!!
87 R10 Silverado Fleetside 355 MPFI 700R4 3.42 Locker (aka Rusty, aka Mater)

Offline Chevygold

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Re: Ignition switched feed for choke?
« Reply #11 on: October 22, 2019, 02:17:54 PM »
As far as I can tell I don't have the choke warning light on my '76, nor do I have a choke fuse in the fuse block, anyway plan is to do what I did with my Corvette, I took supply from the ignition controlled terminal in the fuse block to a relay to switch the relay then a live feed to the relay then from the N.O. contacts to the choke but in this case I'll take the relay coil supply through the OPS, I'll fit an in line fuse in the supply to the choke heater to be sure.
I took the Bubba "fuse" out tonight and put a proper 20A fuse in it's place, also fitted a fuse for the wipers which was missing didn't have time to try them though, then noticed the radio fuse was blown but not concerned with that for now unless it controls anything else important?
Graham