[Fullback66]

I have a 66 GTO Tripower. Last fall and just recently this spring when I start the car it wants to idle at 3,000+ Rpm.

I open the hood and manually move the Thermostatic Coil part to slow the Idle.

When the engine warms up everything is fine.

Does any know what I need to do to solve this problem?

Is the Thermostatic Coil bad?
It there something I need to adjust?

Please help
Thanks
FB66

[carbking]

Check the choke pull-off for correct function.

Jon

[Fullback66]

How would I know if it is bad?
FB

[Kenth]

At cold start the choke pull-off will open the choke blade approximately .160"-.190" at rear edge.

[hobbygto65]

There's a fast idle screw on the driver side of the center carb, just adjust it.

[Kenth]

The fast idle screw also controls curb idle, wont help if curb idle is fine.

[Dick Boneske]

This first part is obvious--For initial cold startup, you set the choke by depressing the gas pedal and release. The initial fast idle, before you touch the gas pedal again, will be fairly high. This is controlled by the fast idle cam on the driver's side. The choke pull-off cannot overcome the fast idle cam until you tap the gas pedal again. The fast idle cam will then fall to a lower fast idle speed., progressively slower as the choke opens as the engine heats.

I've heard this complaint before. Some have actually ground material off the fast idle cam (at the highest step) to reduce the initial fast idle speed.

[Fullback66]

Mr.Boneske,

That is making sense to me.

The big question.

How do I fix this?

Do I need to take the carb off and do something internally?
What do i need to grind down?
What's it hanging up on until it gets warm?

Sorry for the questions.

We are getting somewhere.
Thanks
FB66

[Dick Boneske]

If this problem showed up without changing anything on your center carb, it's a mystery. When the engine is cold and gas pedal depressed, the choke closes completely. The idle adj. screw on the driver's side is in contact with the highest ramp on the fast idle cam. As I said, when the engine starts, the choke pull-off will not move the fast idle cam to a lower ramp until you tap the gas pedal.

This could not, in my opinion, changed unless parts were changed on the center carb. The only way I know of to change it would be to remove the fast idle cam and grind it so the highest ramp is lower. It is not difficult to remove without taking off the carb.

If you need pictures, I can post them. Let me know.

[carbking]

Easy to check the choke pull-off before thinking about grinding on anything.

(1) disconnect the vacuum neopreme tube from the choke pull-off.
(2) disconnect the link from the arm on the choke pull-off.
(3) gently push the arm inward, hold, and place a finger over the tube of the choke pull-off where you removed the vacuum tube.
(4) release the arm.
(5) GOOD - the arm does not move until you release your finger on the tube
BAD - the arm immediately moves outward to its normal off position while your finger is still on the tube.

One other item to check would be the operation of the choke valve itself. I have seen a number of these carburetors where "mechanics" used an 18 foot cheater bar when tightening the wing nut on the air cleaner (maybe not quite 18 foot ), pulling the spider holding the stud upward, and slightly warping the sides of the airhorn to where the choke butterfly would stick when completely closed. To test, simply push the butterfly closed after starting the engine and getting it hot. The butterfly is offset on the shaft, and the offset mass should allow the butterfly to drop open, or you should be able to touch it, and it should drop open.

A very famous scientist (Dr. Van Brahn) stated that 1 test is worth 1000 expert opinions.

Jon.

[Fullback66]

Good information Jon.
I will check it out.
Thanks again!
FB66