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I recently picked up an ‘83 that really doesn’t want to cold start. I found the choke butterfly valve doesn’t close when the **** is pulled. The rest of the choke linkage works normally. The previous owner did a rats nest delete and stripped the carb so I am not sure what I am missing. If there a point in the choke linkage that closes the butterfly valve or is it vacuum operated? Appreciate any help.
The choke **** is directly connected by cable to the carburetor.
It's been a long time since my car was stock, but there should be 3 cables going to a stock carb: throttle, choke, and hot-start. The hot-start connects from an actuator on the driver side strut tower.
If you mean the choke doesn't remain closed when cold, the electromagnet behind the dash is broken or malfunctioning. I used to put a dime on the rod to hold the **** out.
Depending on the year the choke is affected by a couple things, mainly the choke cable. There is also one (or sometimes two) vacuum pods that connect to it as well as the bimetal spring. Unfortunately I'm in the same boat as the above two folks where I haven't looked at a stock carb in a while, but given that you've said it's been stripped, well, that affects things. Looking at the diagrams found in the fsm will probably be the most helpful, although if you feel like throwing some photos up I bet some of us would be glad to offer some input on the situation.
If I recall correctly (not certain here), the choke **** allows the choke to close, but the actual closing action comes from the bi-metal spring...? Don't quote me there, I'd have to look at one again to be sure. The vacuum pod on the front side of the carb can then pull the choke open a hair under certain situations. Photos would really be the most helpful since one person's "stripped Nikki" can vary greatly from another's.
The choke cable to controlled by the water temp sensor on the back of the water pump. If that sensor isn't functioning correctly, the choke will not stay out or retract. The temp sensor controls an electro-magnet in the choke mechanism in the dash.
OK, let's try to use some clear info here.
1st up, does the **** stay out with the ignition on?
If it doesn't then you need to reinstate the water temp sensor wiring to the sensor on the rear of the water pump. For that you will need to use the wiring diags from the FSM
2nd, is there still a brown wire going to the outside (ie Passenger side) of the carb and there connecting to a wire to the carb bi-metallic strip canister ?
Again, if not then you will need to reinstate that wiring.
3rd, is there a vacuum hose from the spacer under the carb (again outside) to the vac canister at the inner end of the bi-metallic canister ?
If the vac can has been removed or disconnected from the bi-met linkage then you likely need to look for a replacement carb.
Simplifying a bit, essentially the choke system works like this:
Ignition power goes through the temp sensor to an electro magnet in the choke **** assembly, and this is what holds the choke **** out until a pre-determined temp is reached.
The choke **** and cable pulls the carb linkage into a position that frees the vac canister to pull the butterfly into the closed position.
Engine vac then does the actual moving of the butterfly into the closed position..
The bi-metallic strip acts against that closing so that as it heats up the butterfly is opened.
Eventually in a cold climate like yours, the water temp sensor will go open circuit and the choke **** will return to the at rest position.
So your choke **** really doesn't control the choke, it just allows the auto choke system to work!!
If I read the original post correctly, the PO is simply wondering why the choke **** being pulled doesn't translate to the choke being closed. Not whether the whole system is working, as evidently the carb is stripped and rats nest is no longer present.
That said, I went ahead and took a gander at one of my stock carbs and indeed my memory was right - the bi-metallic spring is required* for the choke to close itself. Essentially the bi-metallic spring is trying to close the choke butterfly 24/7, although the cam that the fast idle and choke cable are joined by prevents the choke butterfly from closing when the choke **** is in the "off" position. Without the bi-metallic spring, as the choke **** is pulled out, there is nothing to open the choke flap/butterfly and so it just sits there, doing whatever it pleases within the range allowed by the now "open" fast idle cam. As a side note, the additional vacuum pots and the like are extra's for more precise control; without them the choke would still function so long as there is some sort of spring (ie, the bi-metallic spring).
Fortunately there is an easy work around, as this system functions almost identically to the vacuum secondary "permissive" cam. Either you can finagle a wire tie on the linkage to hold the two linkages together, or you can add a small tack weld. I would suggest trying a wire tie first since a tack weld may make future disassembly more difficult. In the below photo I have circled in red where the two linkages meet/the location a weld would be placed.
In the photo the lower linkage is the "fast idle cam" and the upper linkage is directly attached to the choke rod. You can also see how the choke rod linkage arm extends into the bi-metallic spring assy. This is where the tension force would normally derive from, allowing the choke to close.
So yeah, essentially if the bi-metallic spring assy has been removed (which it probably was based on most carb stripping tutorials) then the choke will not work without either a tie or a weld.
Benjamin4456 is correct of course, the bu-metallic spring does the closing, not the vac canister (dunno what I was thinking the other day!)
Had a '82 s2 brought in yesterday on a trailer, similar story.
We tried the manual choke trick with a wire link, seemed all good then in cold evening air but not very satisfactory today in warmer air.
New owner has decided he wants it all back to original so I'm very happy our cars don't have as many temp switches etc as yours do.
01-03-21, 07:25 PM
