Hello all,
With the engine running, and putting out 13.7 volts........I only get 7 volts at the red lead to the electric choke - which may be why the choke plate is a little unresponsive. A search here said that 12 volts is the minimum needed. My diagram wasn't much help to learn what that circuit is shared with. Any suggestions on what to do next? I don't have any other electrical problems.
(knocking hard on wood)
Thanks, Tom

Tom,
What year car and what type of carb ? Do you have a good ground for your meter that you are testing with ?

71 402??? If the choke is wired on the resister wire for the points ignition, then thats the reason why the voltage is low. What color is the wire going to choke, does it have a cloth covering? For another 12 ign on source, you can use the IGN terminal at fuse box, tap off hot lead on on wiper motor, or use the horn relay and add a relay... many options.

Hi, yes it is a '68 model with a '71 402 engine. Also has HEI.
The wire lead is red with sort of a fabric covering, disappears into a wrapped main harness and appears original. The meter I used was grounded to the engine. I've replaced all the ground cables and wires everywhere, which has given me fully working electronics for everything else. Should I run a new lead direct and not use this red wire?

Tom, Greg has it right. Going to the fuse box will be the best way to find a switched 12V source.

If I remember right ,you want to use power that come on when you turn the key You do not want it live all the time Just something to watch out for.

A fabric covering is not a good sign.

On my '68 this wire seemed to be yellow and is in fact a resistance wire to drop the voltage through the coil/points. You should check the voltage to your HEI to make sure it too is not being starved.

I removed the resistance wire and replaced it with a regular wire by removing the terminal from the bulkhead connector and inserting a new one. My electric choke hangs off of the same wire as I use to power the HEI.

Thanks to you all for the help.
I'll investigate the wire source and switch over to an accessory source if that is what it takes to regain 12 volts.
And I'll check the volts going to coil....never needed to but I may learn something....
Tom

And I'll check the volts going to coil....never needed to but I may learn something....
Tom
Check with the engine running. The resistor wire will show close to system voltage with no load, but with the engine running and current flowing to ignition, voltage will be much lower.

Check with the engine running. The resistor wire will show close to system voltage with no load, but with the engine running and current flowing to ignition, voltage will be much lower.
No, not quite true.

Typically you *do* want to measure voltages under load. A battery for example will read a higher voltage until you put a load on it.

For the ignition circuit the current (and hence load) is primarily a function of resistance in the wire and in the coil windings. If the ignition circuit is activated you will have a different lower voltage than if the ignition circuit is not activated. Note use of the word "activated" rather than the more common "turned on". To be activated the ignition must be both turned on and have the points closed. So if the engine is not running, this will depend on exactly where the engine stopped.

However if the engine *is* running then you have a continuous/regular change in load and voltage can bounce around. After the voltmeter averages this out you will likely not see an accurrate voltage either.

If you really want to measure this circuit I would ground the points wire and turn on the ignition with the engine stopped.

However if the engine *is* running then you have a continuous/regular change in load and voltage can bounce around. After the voltmeter averages this out you will likely not see an accurate voltage either.

If you really want to measure this circuit I would ground the points wire and turn on the ignition with the engine stopped.
He has a HEI, not points. Not accurate but it will be lower. Voltage will bounce around more at idle than at faster speeds. In any case, if the HEI, (or just about anything else) is wired to the resister wire, it needs to be removed or rewired, which is what we are both trying to tell the original thread starter.

Yep Greg, we definitely agree on replacing the resistance wire.

I had lost track of the fact he has HEI, I think we have a couple of these resistance wire / voltage measuring threads floating around at the moment.

I remember finding that mystery wire when I overhauled my engine harness a couple summers back. Now that I think about it I don't really remember just how they had the HEI powered. There was some weird stuff there though...

Yep Greg, we definitely agree on replacing the resistance wire.

.

I appreciate the replies. I'll re-wire the choke first, and likely the HEI afterward. But I'll leave the original wires carefully smoothed out and wrapped neatly out of the way. For two reasons: in case someone in the future wants to re-use them to go back to original since they are uncut and in good shape, or to befuddle the bezeejus out of someone in the future who'll look at them and say 'dang -what do all these wires go to?' like we have all had to do in the past. Life is boring without a mystery every now and then!
Again, thanks
Tom
p.s. I wish I had points - attached to an original numbers matching 396 engine ;)

But I'll leave the original wires carefully smoothed out and wrapped neatly out of the way.
Just be sure they can never get shorted out as they are not fused and only protected by the fusible links. (assuming they are still there) If they are still there and they shorted out, you would lose power to the entire car and if they are not there you would end up with a melted harness or worse.

Just be sure they can never get shorted out as they are not fused and only protected by the fusible links. .

Thanks Greg, will do. I can never get enough tips like these. Tom

Personally I think you have it backwards... I would rewire the HEI and then the choke. That way you can run two wires into the HEI power connector: one feeding power in and another going forward to the choke. Simpler wiring run, less wire required.

Simpler wiring run, less wire required.

Hmmm, sounds good. Would make a cleaner appearance too........