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73-87 Chevy _ GMC Trucks => Engine/Drivetrain => Topic started by: harcorshe on July 19, 2015, 08:50:50 pm

Title: Building Wiring Harness for Electric Choke
Post by: harcorshe on July 19, 2015, 08:50:50 pm

I have a '78 K20 with a swapped in 454 and a Edelbrock carb with a manual choke.

The manual choke wire snapped, and I would like to install an electric choke conversion kit. I have read a bunch of posts about wiring the choke through the oil pressure switch. 

Here is my situation. I have a working oil pressure gauge with a single terminal plug on a 14g Dark Blue wire going to the pressure sender.

Based on the GM Wiring Diagram, I think I should also have a three wire plug with one Brown/White wire (ACC); one Dark Blue wire (Oil Pressure Switch); and one Light Blue wire (Electric Choke).

I can't find any sign of this wiring. I also can't find an oil pressure switch. Checked behind the distributor. Not surprisingly, the tell-tale oil light in the instrument cluster doesn't work.

If I am correct that I should have an oil light (triggered by the switch), and an oil gauge (operated by the sender), then I would like to rewire for a switch, and run this to the new choke.

To do this, I think I can get a "t" fitting, for the sender and add the new switch.
Get a normally open three prong switch
Run an ACC wire to the switch
A wire from the switch to the choke
A wire from the switch to cluster light.

See any issues?

Thanks

Title: Re: Building Wiring Harness for Electric Choke
Post by: bd on July 19, 2015, 10:06:09 pm

Is there a Choke light in the dash that you want to use?  The oil pressure switch you need has only two prongs...

(http://forum.73-87chevytrucks.com/smforum/index.php?action=dlattach;topic=28784.0;attach=26340)

It can be installed in the oil galley tap located above the oil filter.  One prong connects to ignition power.  The remaining prong connects to the carburetor electric choke thermostat (and the "ground side" of the choke light if you elect to use it).  Use ignition to power the circuit rather than accessory so the circuit and choke light aren't energized if you are just listening to the radio in the accessory position.

Title: Re: Building Wiring Harness for Electric Choke
Post by: harcorshe on July 19, 2015, 10:52:42 pm

Thanks!

Title: Re: Building Wiring Harness for Electric Choke
Post by: Stewart G Griffin on August 07, 2015, 07:17:24 am

Sorry to hijack but do these need sealant?

Title: Re: Building Wiring Harness for Electric Choke
Post by: bd on August 07, 2015, 09:23:02 am

The switch and sender thread into a pressurized oil galley.  Since the two-prong switch is isolated from ground, use Teflon tape, PTFE paste sealant or blue Loctite on the threads to prevent leaks.  However, the single-prong switch MUST ground to operate the oil gauge or low oil pressure light, so only use Teflon paste to seal the threads.