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Old 08-10-2018, 11:07 AM   #1
WB72
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Help identifying these parts on Mono-Jet

I am looking for help identifying these two parts that have wire connections.

Which one is the choke?

Which one is for the TCS?

There are two connectors with 3 wires going to it, two are detached (Green with White stripe and the Blue), and the Brown with White stripe is still connected.
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Old 08-10-2018, 11:51 AM   #2
LH Lead-Foot
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Re: Help identifying these parts on Mono-Jet

WB72 Hello. Can you provide some info that I may be able to help. Year, engine and carb number? I have a OEM GM book and list carbs by number, application, parts, jets sizes, etc. plus complete rebuilding sheets. It spans from 1947 - 1989 and is 6" thick. Guys call it the "Carb Bible Book #2", I don't remember the number but it's in the garage.
As for the wires, one looks like the throttle kick, the other almost looks like 10SI alternator. Not sure on the choke. Is it electric? Get back with info when you are able, I am not sure if you have the application list in your profile as I looked. Not sure how everything on these forums work, so let me know.
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Old 08-10-2018, 12:06 PM   #3
68 P.O.S.
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Re: Help identifying these parts on Mono-Jet

The blue, green, and brown wires go to the TCS. There's also a black wire that goes down to the tranny for the TCS. As for the choke, idk, I'm not familiar with monojets. Does it even have an electric choke?
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Old 08-10-2018, 03:04 PM   #4
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Re: Help identifying these parts on Mono-Jet

Quote:
Originally Posted by LH Lead-Foot View Post
WB72 Hello. Can you provide some info that I may be able to help. Year, engine and carb number? I have a OEM GM book and list carbs by number, application, parts, jets sizes, etc. plus complete rebuilding sheets. It spans from 1947 - 1989 and is 6" thick. Guys call it the "Carb Bible Book #2", I don't remember the number but it's in the garage.
As for the wires, one looks like the throttle kick, the other almost looks like 10SI alternator. Not sure on the choke. Is it electric? Get back with info when you are able, I am not sure if you have the application list in your profile as I looked. Not sure how everything on these forums work, so let me know.
LHLeadfoot,
The carb is off a 72 C10 L6 250cid the only numbers I pulled off is:7042027 138 2 10, maybe this helps to find more info.

My profile is not updated, i am working on a frankens-10 right now, 67 Shorty built with a 72 drive train.
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Old 08-10-2018, 03:06 PM   #5
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Re: Help identifying these parts on Mono-Jet

Quote:
Originally Posted by 68 P.O.S. View Post
The blue, green, and brown wires go to the TCS. There's also a black wire that goes down to the tranny for the TCS. As for the choke, idk, I'm not familiar with monojets. Does it even have an electric choke?
68 POS
I know that the choke is not mechanical, so i am guessing it is electric, unless there was some other method back in the day.

This is my first Mono-jet as well, this is a learning curve, that is for sure....
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Old 08-10-2018, 03:47 PM   #6
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Re: Help identifying these parts on Mono-Jet

You have a thermostatic coil spring choke. If you look at the choke plate and the bell crank connected to it, you can follow the rod down onto the top of the exhaust manifold. I can't see it for the rest of the stuff in the way, but that is where it is supposed to be. It isn't a manual choke carburetor, because there is a choke pull off assembly on it. That's the vacuum can opposite the bell crank.

Look at your connectors. Does the one with two wires plug into the idle stop solenoid? I thought those had one wire and were chassis grounded, but I'm a little hazy on that memory.

The TCS system was used to limit vacuum advance until the vehicle was warmed up and in high gear. This served to cause faster warm up and to limit hydrocarbon emissions. It is pretty much only a California emissions system, and can be bypassed if you want. Simply take the vacuum to the thermostatic switch (if still so equipped) and connect it directly to the vacuum advance chamber. You can also remove all the wires, if you want, as they won't serve any more purpose once the vacuum side is dealt with. You might want to keep the parts in case someone wants to put their system back to stock.
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Last edited by Steeveedee; 08-10-2018 at 08:56 PM. Reason: typo
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Old 08-10-2018, 07:44 PM   #7
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Re: Help identifying these parts on Mono-Jet

For that carb you should have a bi-metal choke coil inside a Choke Stove on the side of the exhaust manifold. A rod from the choke arm goes down to the choke stove. It looks like you may still have that rod.

If I were keeping a 1bbl carb, I'd get ride of that smog monojet garbage and replace it with a Rochester B which was original to '67 inline 6.

The Rochester B was for a manual choke and if your '67 still has the manual choke cable, I would go that route.

If your '72 exhaust manifold has the Choke Stove and the choke cable is missing you could try to find a Rochester BV.
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Old 08-17-2018, 12:53 PM   #8
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Re: Help identifying these parts on Mono-Jet

Well, even with all of the original information provided by the Delco Carb Book #9 which I spent 3+ hours looking thru, here is what I can tell you.
The carb number does not appear in print, but is not uncommon, it does indicate it is a 1972 monojet for the 250 cu. in. engine. (Photos below)

While the choke is controlled by a choke stove and linkage and did not use a cable. (Photo below)

The "Green" wire is generally hot with the key. It controls the throttle stop solenoid that is used to adjust idle speed when warm. It drops the throttle closed when shut off to prevent "Dieseling or Run-on". It is adjusted for correct idle speed after correct timing and air/fuel is adjusted and the engine is at temp.

The "Yellow" solenoid was a mystery until my Detroit GM buddy came back from vacation. He indicate that the Muncie 426 manual trans came with variations that included up to 2 "PTO" plates to add pumps, drives and other things that could be added at the dealer or an outfitter for a dump flat bed application. It would be adjusted to hold the engines RPM speed desired for PTO operation for what they installed.
Many kits where sold with Delco parts, wires, switch and etc. at the dealer, but installed elsewhere. The PTO would be operated or engaged with a large knob choke type cable to the gear box on the tranny. A switch would be added under the dash that raised the engines speed for hands free operation of the power-take-off device. It could be removed without effecting the carburetors operation. Bobby G. has been with GM since 1972 in various capacities.

Yes, while it true that many manufactures used a 4th gear switch to retard ignition timing to prevent ping or knock (Even Imports) when using small 4 or 6 cylinder engines. Bobby G is positive the solenoid was for PTO operation.

Check it first to see what it touches. If it pushes on the throttle in such a way as to open it when energized to raise the engine speed, that is what it was for. It is hard to tell from the photo's you posted. Due to it's size, it will push hard and is designed for long continuous operation. If one wire, it's ground thru the body. If two wires, well the ground and positive both are required...but it is optional GM equipment and somewhat a rare find.

If it works this way, as I said it could be removed. Someone out there may want to buy it to keep their truck original when equipped with a PTO device.

My 67 C10 came with this tranny, while in first gear, you could get out and walk faster than it moved. These where built like tractors with a cab on them.

Best of luck. Hope this helps.
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