1960 Choke Trouble

[60eldo]

  So when my car is cold, I step on the gas pedal and butterfly shuts.  Its starts right away and sounds good reving about 1100rpm, After about 20 seconds it starts to stumble and blue smoke comes out of the tail pipes like shes starving for air. I look at the butterfly and it is open slightly,,what going on here?

[2danreed]

Next time you cold start the car remove the air cleaner lid and manually open the butterfly with your finger and I bet your RPMs will rise and the engine will smooth out. Sounds like the butterfly isn't opening enough once the engine is running and your running rich.

Now, how to fix this issue? I'm not sure. If you adjust the choke spring to solve the issue you are having you'll likely have the opposite problem of the butterfly not closing enough to allow the car to start. Hopefully someone here can shed better light.

[Daryl Chesterman]

Jon, has the car just started doing this?  If so, you should remove the choke cover that has the bimetal spring attached and see if the housing has a lot of carbon in it.  If it does, then the heat tube that runs through the intake manifold has burned through, allowing exhaust gas to enter the choke housing.  The carbon is keeping the choke pull-off from doing its job.  If the carburetor has had recent work done on it, it is possible that the choke was not indexed properly.  If that is the case, it is easy to get it set correctly.  On a cold engine, somehow wire the throttle so that it is open a little bit (this will make it so that the linkage doesn't bind on the fast idle cam), then loosen the three screws on the choke cover just enough to be able to turn the cover and set it so that the choke butterfly is just closed, no more.  Tighten the three cover screws and remove the wire holding the throttle open, start the engine and see if that did the job.

Daryl Chesterman

[60eldo]

  Daryl, yes it just started doing that. I agree could be the exhaust tube. Lots of carbon in the spring, But I dont get what you mean burned through. Its an empty pipe, please explain. OK, I took another look. You arent talking about the tube that goes from the choke cap to the manifold. Are you talking about the one inside the manifold, if so how to get that out?

[gkhashem]

you need to remove the intake to replace the crossover tube inside the intake.

here is one

https://www.ebay.com/itm/1959-Cadillac-Engine-Intake-Choke-Tube/192181494437

the external tube you can see gets connected to the intake where this tube is in the intake.

If it is rotted you get all that carbon.  so you need to clean external tube, spring housing and i bet replace internal tube as on ebay.

If you do not it will only clog up again.

[Daryl Chesterman]

George's advice is all good.  I have never had to replace the tube in the intake manifold.  Hopefully someone will weigh in on this and give you some good pointers.  Another thing you will want to check is your exhaust heat riser valve, if you still have one.  Be sure it is free to rotate, and not rusted in the closed position.  If it is constantly closed, it forces hot exhaust gases to pass through the crossover passage in the intake manifold and will cause premature erosion of the choke tube and possibly cause the intake manifold to crack.  While you have the intake manifold out you should have it magnafluxed to see if there are any cracks.  Some people who are not purists, will wire the heat riser valve in the open position to prevent these problems.  The only downside to doing this is that if you live in a cold climate, and drive your car in the winter, it will take a little bit longer to get the engine warmed up, so it might affect cold driveability until the engine is warmed up.

Daryl Chesterman

[gkhashem]

Darryl

Lucky man, mine was rotted in a 1966 with 62K miles and a 1959 Olds with 48K miles.

The signs were a clogged thermostat housing and the outer tube feeding it.

Olds was so bad I had to get outer tube boiled out. It prevented the spring from opening fully when warm.

Also can tell from grabbing the external tube when warm but BE CAREFUL it should be so hot you cannot grab it since it should burn you!!!

If not it is clogged. But rereading the original poster should it not be slightly open when cold until warmed up and then fully open when warm.

So we might have a different issue like an idle  screw not set right. I say do a tune up first.

[Daryl Chesterman]

George and Jon

This thread about how the choke heat tube works in conjunction with the choke housing will explain what Jon needs to do to clean out the carbon in his choke housing.  It is imperative that the carbon is cleaned out of the vacuum passage between the choke housing and the carburetor body, or the choke butterfly will not open up the way it should as the engine warms up.  Jim Eccleston (quadfins) does an excellent job of explaining the operation of this system, along with pictures showing what he is explaining.

http://forums.cadillaclasalleclub.org/index.php?topic=160306.msg464828#msg464828

Daryl Chesterman

[gkhashem]

George and Jon

This thread about how the choke heat tube works in conjunction with the choke housing will explain what Jon needs to do to clean out the carbon in his choke housing.  It is imperative that the carbon is cleaned out of the vacuum passage between the choke housing and the carburetor body, or the choke butterfly will not open up the way it should as the engine warms up.  Jim Eccleston (quadfins) does an excellent job of explaining the operation of this system, along with pictures showing what he is explaining.

http://forums.cadillaclasalleclub.org/index.php?topic=160306.msg464828#msg464828

Daryl Chesterman

No need to direct it to me I have done this a few times, but again the choke butterfly should be slightly closed or closed still at 20 seconds from start. No doubt you need to clean it out so it will fully open when warm.

Whether the tube is clogged or not?

Blue exhaust smoke only at start-up can indicate worn piston seals or damaged or worn valve guides

  So when my car is cold, I step on the gas pedal and butterfly shuts.  Its starts right away and sounds good reving about 1100rpm, After about 20 seconds it starts to stumble and blue smoke comes out of the tail pipes like shes starving for air. I look at the butterfly and it is open slightly,,what going on here?

[60eldo]

    So if I install a manual choke and remove the   S  tube that goes from the manifold to the choke housing,,,,will it stop smoking?

[fishnjim]

This is not fuel injection,1960 technology...   Assuming it's a original 4 BBL:
When you step on the gas before the choke opens you're kicking the throttle off the fast idle cam, which disengages the choke linkage.   So it's trying to run with the choke shut and eventually floods out.
Wait til the choke opens before stepping on the gas.    Unless you live in the arctic at this time of year, it should be warm enough to not even choke.   Could be it needs adjusted/cleaned, and if the choke cover has been opened make sure the spring is on in the proper direction, otherwise, it'll close the choke not open it.
The proper procedure is to depress the throttle fully, let off, then start.   That sets the fast idle cam.  Do not pump it or rev it.   Let it warm up.   If it's properly adjusted, it'll idle up until the choke opens.   

[60eldo]

   Thanks but, in the morning car is cold.  I step on the gas twice, which closes butterfly and car starts right up at fast idle. Now I dont touch the gas and after about 45 sec, the engine starts to spuder and smoke starts piling out the tail pipes til I hit the gas down. Then it stops smoking and is on slow idle

[quadfins]

You can adjust the tension on the choke coil. If you ease off the tension, it will open the choke butterfly earlier and with less warm up.

Loosen (don't remove) the three small screws on the round black spring housing. You can now rotate the housing. As you do so, you will see the butterfly opening or closing. Adjust it so it is more open/less tension, and see what that does. Repeat as necessary until you are satisfied with the results.

Jim

[Daryl Chesterman]

Jon, the choke system will never work properly until you clean out all of the carbon in the choke housing-- unless you put in an electric choke, or a manual choke.  If you want to use the OEM choke system, you must clean out all of the carbon and replace the burned out tube in the intake manifold.  Not to beat a dead horse, but as I posted above, the explanation by Jim Eccleston (quadfins) explains the operation of the OEM choke system.  If the system is working properly, the choke butterfly will open up as the engine warms up, without you having to do anything to the accelerator pedal.  Granted, the engine will stay on fast idle during the warm up, which it is supposed to do, but the choke butterfly will open up without having to tap the accelerator pedal.

Daryl Chesterman