Auto electric choke hook-up

[Bob McMulkin]

On a 1956 Model 62 where is a electric choke hooked up that is close to the carb??
any help would be of great help...thanks

[Jon S]

There is no electric choke on a 1956 Cadillac.

[Scot Minesinger]

I think electric choke was 1976 (maybe 1975)

[TJ Hopland]

I assume this was an air heated choke that has not been working reliably so you have an electric heater for it?   Is yours a Carter or Rochester?

I may be looking at the same thing on the 57 I am working on.  First thing I am going to make sure the air passage in the carb is not blocked.  If its not then I suspect that the car originally had a 'heat riser' flap in the exhaust that forced more heat into the intake and that extra heat helped the choke warm up.

Where to hook up is a good question.  The generators don't have a key on line to them like the alternators do.   Factory electric chokes took a key on voltage and ran it through a second set of contacts in the (3 terminal) oil pressure switch so it would not start heating till the engine was running.  On my project I am thinking of adding a new power distribution block connected to the battery or at least battery cable and part of this block will be a modern heavy duty relay tied to a key on source.   That way the modern items I am adding won't be stressing the original wiring or components like the ignition switch which does not appear to be an easy to find part.   I hate to start adding stuff under the hood but for a driver you need some modern stuff.   When I do it I will try and use existing holes for mounting and running wires so things could be returned to stock if anyone ever wanted to. 

The original air heated chokes that were mounted on the carbs had a small vacuum port from the choke housing to the carb that would draw the hot air from the exhaust manifold on the inlines or the exhaust crossover in the intake on the V's.  There usually is not any sort of filter on the inlet for this circuit so it can easily get plugged up.  No airflow no heat no choke unwind.  Guessing that is one reason for the 'divorced' choke design where they put the coil down in the intake and had a rod up to the carb.  No ports to plug up. 

Another note since I'm assuming the electric choke you got is a semi universal aftermarket part, make sure you got a 12 volt model.   Fords with alternators had a special terminal on the alternator to run the choke (was only live when alternator was spinning) and this terminal was not on the regular DC side of the system so you got a sort of half wave voltage out of it that was more like 7 volts.   Put one of those coils direct to 12v or more like 14 with the engine running and they don't last long.   Ask me how many I went through before I learned that.   Actually I never did learn till I got my first Ford.     

[Jon S]

The heat tubes were pretty fool proof and mine works perfectly 57 years later.

[TJ Hopland]

I suspect how well the heat tubes worked depended on the ambient conditions they were exposed to.   Some areas have more things floating in the air or getting kicked up off the roads that got sucked into the system and plugged em up all the time.

[Jon S]

I suspect how well the heat tubes worked depended on the ambient conditions they were exposed to.   Some areas have more things floating in the air or getting kicked up off the roads that got sucked into the system and plugged em up all the time.

Not really - the heat tube is a relatively closed system utilizing exhaust gas to warm the Climatic Control.  If the engine was poorly tuned, I guess excessive carbon could clog the tube.  Mine has been trouble-free for 57 years although I did clean a pin sized bubble of carbon from the heat shield/diverter in the Climatic Control once.

[Dan LeBlanc]

There should never, ever be carbon in the choke tube.  Just the design of the intake manifold.  The presence of carbon indicates a cracked choke tube.  When the heat riser valve is closed, exhaust is diverted through the intake centre runner which warms the tube.  It is open on the underside of the intake manifold with a spiral affair inside to slow the air passing through it to allow it to heat more.  Yes, there is partial vacuum, but since the tube is open to atmosphere, it should only pull in clean air.

If you check a FSM for a cross section of the intake, you'll see that you should never have carbon there - by design.

The only thing a poorly tuned engine could clog is the crossover under the carburetor, just forward of the primary bore in the intake where hot gases pass through to warm the carburetor.

[Jon S]

There should never, ever be carbon in the choke tube.  Just the design of the intake manifold.  The presence of carbon indicates a cracked choke tube.  When the heat riser valve is closed, exhaust is diverted through the intake centre runner which warms the tube.  It is open on the underside of the intake manifold with a spiral affair inside to slow the air passing through it to allow it to heat more.  Yes, there is partial vacuum, but since the tube is open to atmosphere, it should only pull in clean air.

If you check a FSM for a cross section of the intake, you'll see that you should never have carbon there - by design.

The only thing a poorly tuned engine could clog is the crossover under the carburetor, just forward of the primary bore in the intake where hot gases pass through to warm the carburetor.

Dan -

The 1957 (and 1958) choke tubes connected directly to the passenger side exhaust manifold and ran up to the Climatic Control.

[dplotkin]

Where to hook up is a good question. 

And here's the answer, to the input (switched) side of the ballast resistor.

Dan

[TJ Hopland]

Hooking to the ballast resistor is reasonable and sort of in the right area.   I just worry about adding loads to wires that were not likely over-sized when they were new which was a couple years ago.   That would be a good under hood source for me to run the relay that I was talking about.  A new feed wire (fusible link) from the battery to the relay then relay coil runs off the resistor wire so it get energized with the key and you now have 30 amp of switched power to run stuff like an electric choke, electric wipers, cruise control, radio, AC, whatever.     

Carbon in the choke?  I was going to say there is a problem if you have that going on.   Here are some photos of an experience I had like that.  This was not a Cadillac or even a V engine but you can see how odd the problem was. 

This was on car that was not running when I bought it and had been sitting for several years.  I cleaned up the carb and got it running and could hear a slight exhaust leak and see a couple tiny cracks but didn't think it was a big deal.  Within a few days the choke quit working again, vac passage got plugged.  I was puzzled.   The yellow circle lower left is where the choke tube connected.  There was a tiny crack there so I suspected that was maybe causing the leak letting carbon or cold air in so I ordered a new manifold.

 

Got the old manifold off and saw all this.  That crusty thing in the middle of that one port is the choke passage.  Its supposed to be a tube cast in place with a hole drilled through it.   You can see the hole in the top that is the air inlet.   The 'fresh' air in this case gets sucked through that hole in the bottom of the manifold behind the down pipe then through that tube that is cast into the manifold which is in a Siamese exhaust port so it gets plenty of heat going past it that then heats the air in the tube that then heats the coil and unwinds the choke.   Any system with the choke coil on the carb that has a tube has some thing kinda like this somewhere in the system.   If its not something cast into the exhaust manifold its cast into the exhaust passage in the intake.  Some of the more simple or aftermarket systems were a 'tin' box or 'stove' that was strapped to an exhaust pipe or manifold.  It did the same thing, the manifold heated the box which then had the connection for the tube up to the carb.    Its weird what heat can do to cast iron, I could pick the cast iron out of there with bare fingers. 

[TJ Hopland]

Just went out and started to tinker with my non working choke project and pulled the choke tube off.   I got hot exhaust coming out that port on the intake so if I am lucky I got a bad intake gasket leaking exhaust right where that port is.  If I'm not lucky the inside of my intake looks like that exhaust manifold in my photo.  I have a blown out exhaust manifold gasket on that side too so its hard to narrow things down by sound. 

It looks like I have a deeper issue(s) that needs to be addressed and I'm gonna have to take the carb apart to get the carbon out of the vacuum port but I did find this info on the web if you have a Carter AFB and want to go electric.  It does not address the where to connect issue but it does give you an idea what has to be done.   I checked and my local Napa stocks that Edelbrock kit.
http://www.hotrodhotline.com/md/html/electric_choke_conversion.php

[TJ Hopland]

I also read that the choke coil can draw as much as 5 amps when it first starts heating which makes me think a relay would be best rather than running it off the ignition wire.    From what I have seen of the 50's era cars the ignition circuit does not appear to have any sort of protection in it (fuses or fusible link wires) so if you overload it you are going to start melting wires and or your ignition switch. 

[dplotkin]

TJ-
I have two cars each with electric choke carbs. Edelbrock and Holly specifically direct that it be wired to a switched source of battery current, whether that be off a spare lug in a fuse block, the ignition switch, or if a ballast block is used, on its line side (from ignition switch and not to coil). This is how the majority of folks with aftermarket carburetors have them hooked up. As you can imagine, hundreds of thousands of these have been sold and are used with all manner of 50's wiring. A fuse certainly can't hurt, but a relay is overkill. Certainly if a relay was a good idea Edelbrock & Holly would be pedaling those alongside the carb, which comes complete with the hookup wire and lug.

Dan

[55 cadi]

I have a 55 with climate control non electric that has a tube from the exhaust manifold to the choke.

When I rebuilt the carb there was black soot inside the choke just below the tube to the manifold.

Just posted this to show non electric have the same set up. And to maybe find out why there was black soot in the choke housing as well.