The Stovebolt Site Forums The Shop Area The Electrical Bay Electric Choke?

How exactly does the electric choke work?I understand it opens the carb as it warms up.Where would I "tap"into a hot wire?Could I use the hot wire that goes to the coil?

I believe there is a ceramic heater inside the choke control which heats the bi-metal spring.Connect the hot wire to a switch [key]controlled curcuit

That was why I suggested the coil "hot"wire?.Only hot while key is on-

It's best to use an oil pressure sensitive switch, so if the engine happens to stall when it's cold it won't continue to heat the choke until it's restarted. That's how GM did it when they started using electric-heated chokes in the early 1980's. Ford used a wire from the alternator stator, and actually used AC voltage for the choke heater. Same sort of operation - - - -engine stalls, choke stops heating.
Jerry

Does the generator count?I know that there is a hot wire running to an alterator.But is there one going to the generator?It hasnt gone out yet so I havent switched to an alternator.

I think what these guys are saying is...you need what is refered to as a 'switched' hot wire to your choke. In other words, the wire is hot only when is ignition switch is on. The oil pressure switch is a great idea but if you have the non-electric type you will have to look elsewhere. Not sure about the generator but the 3-wire alternator has a way. The hot wire to the coil is a very commom way to get 'er done. Good luck.

It's not a good idea to hook mit right to the coil. Find a place on the fuse block or ign. switch that is hot with the key on. Put an inline fuse in the circuit with a 5-10 amp fuse. The oil pressure switch is a good idea but not nessesary. You can put a tee fitting in the outlet for the gauge/light sender. Get a 2 prong switch from the late 70's early 80's. & wire it in the circuit.

so if not the coil;then where else in the engine compartment?

Now this is on a mustang.. but i hooked my electric choke up to my voltage regulator. The key on side.

If you have a ceramic resister on the fire wall You can hook it to the side that goes to the switch. If not run it through the fire wall along with some of the other wires. Again, put a fuse in the circuit.

Not good. Hook it to the neutral tap on the back of the alt. like Hot rod was refering to.

Danny,

After getting similar advice (here) about using an oil pressure switch, but no information about which switch, I checked out a wide variety of switches.

"Any of the fuel injected Chevy V-8's will have a 3-pole pressure switch that mounts in a threaded port just above the oil filter. Two of the terminals are the normally-open fuel pump switch leads, and the third one is a ground for the oil pressure idiot light."

I had to try several two-pole and three-pole switches before I got one that switched appropriately for this application. It switches on at about 4 psi (rated to switch on at 2-8 psi).

NAPA: MPE OP6626SB

I have this now working to control two Carter-Weber Motorcraft 740 2-barrel carbs on a 6v 261 engine. You'll need a T-fitting in the oil-pressure line location. I get the hot lead from the voltage regulator (I wanted a source inside the engine compartment).

have a 6cyl engine with generator.original non-electric oil pressure gauge.might use the voltage regulator-

The reason for using the oil pressure switch is to keep the choke heater from operating if the engine isn't running. It's not uncommon for a cold engine to stall during warm-up, and if it's not restarted immediately, the choke continues to heat as long as there's voltage coming from the ignition switch. That releases the choke coil and the engine is hard to restart. By switching the voltage off with the loss of oil pressure, the choke stays applied. It doesn't matter if you've got a non-electric oil pressure gauge- - - - -all it takes is a tee fitting to expose the switch to oil pressure. Wire one terminal of the switch to ignition voltage, and the other one to the choke coil. You're good to go!
Jerry

Where do I find that "oil pressure switch"?Is this a universal part?

A part number and source (for one type that is now working for me) is given above.

well I dont have a V8 engine.Nor do I have an oil filter.

You do not need a V8 engine?

You do not need an oil filter?

As posted above, "You'll need a T-fitting in the oil-pressure line location."

You put a brass T-joint into the block where the original oil-pressure line goes into the block. You screw the male end of the T into the block; and, you screw the oil-sender line into one female side of the T (an adapter might be needed), and you screw the pressure switch into the other female side of the T (an adapter might be needed).

NAPA can provide any brass fitting made by Weatherhead-Eaton. You'll have to check their catalog for a T-fitting that will work in your situation (trial and error will most likely be needed, perhaps for the end on your existing oil-pressure sender/line). The diameter of the hole in your block is measurable, and the diameter of the pressure switch should be given on the NAPA site.

Here is the switch you need.

http://www.napaonline.com/Search/Detail.aspx?R=MPEOP6626SB_0213430147

The oil gallery you need to access runs down the driver's side of the engine with a 1/8" pipe thread adapter for the oil pressure gauge installed in it just to the rear of the exhaust pipe area about 4" above the oil pan rail. Remove the adapter and install a short 1/8" pipe thread nipple into the block and a 1/8" pipe "T" fitting. Connect the oil pressure line fitting into one side of the T, and screw the switch into the other port. Run a wire from the ignition switch terminal that supplies voltage to the coil to one of the connectors on the switch that is parallel to the other one. Run a second wire from the switch to the choke coil, leaving the center connector of the switch with nothing connected to it. This connector can be used to ground an idiot light, but that's a subject for another "basic wiring 101" course.
Jerry

Yes, that is the part number that I posted. Usually you cannot post a link to a NAPA product (Hotrod Lincoln's link does not work for me - it has a "personal session" code that will only work on Jerry's computer).

Here is the information from the NAPA site:

Oil Pressure Light Switch
Product Line: Mileage Plus Electrical
Part Number: MPE OP6626SB
Price: $5.89

Warranty Limited 12 Months
Attributes # Switch Terminals : 3 Terminals
Oil Pressure Switch Pressure Rating : 2-8 PSI
Oil Pressure Switch Thread Size : 1/8 x 27 NPT
Terminal Type : Blade

------------

3750x2 is mostly likely the T-fitting that will work.

NAPA: WH 3750X2 (search on NAPA site: 3750X2)

Ty for breaking it down for me.Off to NAPA to see ifn they have the parts.Now I understand about how/why to use the oil pressure type of switch.

just took my oil line off.REAL close to the exhaust&the carburetor linkage.

Danny,

What year and size engine are you working on?

270 GMC?

60chevy 235 6cyl

Attatches just below pivot linkage going to the carbthe switch will be here Tuesday.Napa guy said it should screw into the "T"that I bought today.plastic oil line going to dash.replaced oil gauge with aftermarket that shows #'s-25lbs of pressure;stock gauge only showed gauge with "marks"on it.On my 60chevy 235 engine.

Danny,

After checking a few of your old posts, I thought that maybe you were referring to the 270 in your GMC.

Let us know how this works out.

By the way, it sounds like your oil pressure line is attached to the less convenient of the two points to which you could attach the oil-pressure sender. You might be able to more easily attach to the location nearer the rear of the block.

i think it is going to work okay;thanks to explaining how to hook it up.Thanks for being patient.
This site is by far the BEST that I have encountered for assistance.The knowledge carries over to all vehicles-not just trucks!

Hooked up the oil pressure switch.Worked like a charm.

Decided today to add one on my 58 truck.
Once again:THANKS 4 the help!!

BTW:I have a 58 GMC truck&a 60 Bel Air car..Figured same advice would help me on that there 60 BA.
Don't hold it against me.