William Buckley

Had the '66 coupe almost a year. Nothing but carburetor problems since I had it, so had the holly four barrel rebuilt by an expert. Runs great except the damn auto choke does not open all the time, giving me hell in cold weather. After long warm up in the morning, the choke still does not open, causing rough driving problems. Is there a replacement auto choke kit available to solve the problem. New carb rebuild works great except for the old nemesis ..... the damn auto choke. Car is NCRS, so I need to keep a manual auto choke.

tbarb

The choke rod adjustment should be checked first, this procedure is in the service manual. The other part in question is the manifold stove spring that controls the rod mentioned above.

These are very simple adjustments and that choke system is very reliable so you should be able to repair the problem.

Powershift

But you should also temporarily disconnect the rod to the choke plate (top of carb) and make certain that the choke plate moves freely and does not bind or stick. If plate is free (as it should be) then the adjustments mentioned or replacement of the thermostatic coil in the intake manifold SHOULD solve your problem.

Once correctly set, the choke doesn't often go bad on its own.......especially if the car is routinely driven.

Larry

William Buckley

Thanks for the info .... will pass this on to my "supposedly expert cab mechanic".

Nowhere Man

Dumb question is the heat riser exhaust valve on the passenger side exhaust working? If a cast iron intake is the hot slot open under the carb. And do you have the correct S/S baffle and carb gasket?

William Buckley

Answers to questions. The heat exhaust value is working. Supposedly when they checked, the choke flap was working freely without sticking. That leaves the actuation rod and the heat sensitive spring to check. My feeling is that the heat activating spring is not working because on idle when the engine reaches operating temperature gets to normal, the choke remains closed. Thanks to all. This site is so full of useful information.

Powershift

The heat/thermostatic spring can break (not likely) or get sticky (mildly corroded) by time and humidity. You could try WD40 on the spring and see if it immediately is better. However the WD40 treatment will probably not last very long. Maybe remove the spring and check its overall condition.

Larry

Gary's '66

I'm betting on a bad spring.

Gary

William Buckley

I'm thinking that you are certainly correct. Went out on cool morning today, and it started fine using the auto choke. Let it get to normal operating temp, and then depressed the accelerator to lower rpm's. Then the thing goes wild .... running rough and tach acting like tumblers on a slot machine. Makes me think that the auto choke is working, but will not release when the motor gets to operating temperature. Closed garage door, and came back later when the motor had really gotten hot after shut down. It started and ran perfectly. Must be that the temperature operated spring is not working properly. Do you mechanical experts agree?

Nowhere Man

take a min and pull the cover off the spring and have a quick inspection of the spring. the cover is only pressed unto the spring base.

Bluffman

I am also having an issue with the choke, I purchased a new spring, are there any pictures showing the correct position the rod should be in when attached to the spring and carb, mine when attached does not allow the choke to fully go off, I removed the rod and the choke is now off and my car is idling better. Thanks in advance for pictures. Ian

Nowhere Man

Ian you must bend the rod to get the choke to close

MikeM

Sounds to me like the spring is working. Adjust the rod by bending as has been suggested and check for binding. Sometimes, the cover over the spring will bind on the rod.

If you've been driving it with the choke on, pull the dip stick and see if it smells like gasoline. If it does, change the oil.

Bluffman

Thanks for the tip on bending the rod, are there any photos of the set up without the cover on. Ian

MikeM

FWIW to whoever cars. there was more than one choke spring released for the choke on Holley carbs. Depended on the engine, manifold and I think the carburetor. Don't remember but make sure you have the right one.

Bluffman

Thanks Mike, that's why I would like to see a picture of a 327L79 with a Holley carb.

Nowhere Man

Funny you say that Mike the resto houses sell only one. Where can you find different ones.

MikeM

There appears to be only one for 1966. If you look across other years of GM car lines you'll see other options for the thermostatic spring and they will mount to the '66 manifold but will not work.

You'll also find there are quite a number of different rod configurations between the coil and the carb, depending on the application.

There is a much bigger world out there than just the Corvette world.

Nowhere Man

I know they sell many diffreant rods but never heard about diffreant springs.

Bluffman

Figured out one thing you have to pre load the spring before you attach, waiting for engine to cool to see if that worked. Ian