wire electric choke

[scarborough]

in the process of wiring the electric choke on my edelbrock 750 carb. i've read some past post where guys have tied into the IGN on the fuse box, that's the route i would like to go using 18ga wire. should i run a inline fuse also for extra precaution, if so what size do you suggest i go with. i appreciate your feedback

Apprentice

 

[fleming442]

10-15a should be sufficient, but I would step up the gauge to 14 or 16 if you're going all the way to the fuse box.

 

[pontiacgp]

make sure you wire it so the wire is only live when engine is running

 

[WanaBa442]

Stolen off another site:
EDIT: Note updated information

This question must come up monthly, so I figured it was finally time to write a little tech article. Many folks use the wiper power feed, but this has problems. Simply using a switched power source, especially one that is hot in the ACC position, will cause the choke to open prematurely if the key is on but the engine is not running. Also, the combination of the always-on choke heater and the wiper load may blow the fuse.

GM used two different methods to power the choke, depending on the vehicle. Most used an oil pressure switch in the power line to the choke. This way, the choke doesn't start to heat up until the engine is running and there is oil pressure. On my 62 F-85, I ran a fused wire (20 A fuse) from the BATT terminal on the alternator to the switch, and from the switch to the choke. Very simple to wire and very clean. I like to use the Standard P/N PS127 (note updated part number) switch. The middle terminal works the OIL light, the other two are a normally open switch that closes with oil pressure. Use these to control the choke. If you have an oil pressure gauge instead of a light, simply use a brass tee fitting to connect both this switch and your oil pressure sender. The interchange part numbers are as follows:

Standard Motor Products PS127
NAPA ECHLIN OP6618
Airtex 1S6552
BWD S369
AC Delco D1825A

Here's the sender:

Here's the wiring diagram:

 

[fleming442]

Pink is ignition, B.T.Dubs....

 

[Texas82GP]

Just use a scotch-lock on the hot to the coil. That's how my car was done. 😂 Seriously, don't do that.

 

[Texas82GP]

Stolen off another site:
EDIT: Note updated information

This question must come up monthly, so I figured it was finally time to write a little tech article. Many folks use the wiper power feed, but this has problems. Simply using a switched power source, especially one that is hot in the ACC position, will cause the choke to open prematurely if the key is on but the engine is not running. Also, the combination of the always-on choke heater and the wiper load may blow the fuse.

GM used two different methods to power the choke, depending on the vehicle. Most used an oil pressure switch in the power line to the choke. This way, the choke doesn't start to heat up until the engine is running and there is oil pressure. On my 62 F-85, I ran a fused wire (20 A fuse) from the BATT terminal on the alternator to the switch, and from the switch to the choke. Very simple to wire and very clean. I like to use the Standard P/N PS127 (note updated part number) switch. The middle terminal works the OIL light, the other two are a normally open switch that closes with oil pressure. Use these to control the choke. If you have an oil pressure gauge instead of a light, simply use a brass tee fitting to connect both this switch and your oil pressure sender. The interchange part numbers are as follows:

Standard Motor Products PS127
NAPA ECHLIN OP6618
Airtex 1S6552
BWD S369
AC Delco D1825A

Here's the sender:

Here's the wiring diagram:

Great post. FYI...the wiring diagram isn't loading, at least it isn't for me.

 

[WanaBa442]

The other way is to use a relay that is triggered by the field wire on the alternator (brown #1 wire on SI-family alternators, for example). The field wire is only hot when the alternator is turning. This is how GM wired the stock G-body cars with electric choke when the gauge package was installed. Of course the down side with that is that the choke will close if you break the alternator belt. A typical wiring diagram for the second method is here:

 

[gnvair]

I recently wired mine using the oil pressure switch method and it works like a champ. 78-79 V6 cars and all the 80-88 Chevy V8 powered cars are wired this way from the factory.

 

[pontiacgp]

Great post. FYI...the wiring diagram isn't loading, at least it isn't for me.

your clearance level was lowered by GP403 due to your admission to using scotch-locks.......