#1  
Old 09-12-2020, 01:22 PM
lucky1 lucky1 is offline
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Default 66 Tri-Power center carb fast idle adjustments

On a cold start my fast idle is too slow.

I can see the fast idle cam is on the second step, with several more to go.

How do I adjust the carb to engage more steps ?........

Can this be done on the car ?....

Thanks in advance.

  #2  
Old 09-14-2020, 06:53 AM
Tom Vaught's Avatar
Tom Vaught Tom Vaught is offline
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There is normally on the carb a fast idle adjustment screw to set the speed when on the second step. Adjust that screw for more fast idle rpm.

Tom V.

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Old 09-14-2020, 08:44 AM
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carbking carbking is offline
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The position of the screw on the cam is dependent upon the opening of the choke butterfly.

At 65~70 degrees F., and a cold engine, depressing the footfeed and then releasing SHOULD move the choke butterfly to completely closed, with no tension.

Since the 1966 has a divorced choke, changing the thickness of the manifold gasket (or adding a spacer) will change the choke butterfly adjustment. The butterfly is adjusted by bending the rod from the divorced choke to the butterfly.

Once the choke is properly adjusted, then, as Tom mentioned above, the fast idle speed may be adjusted with the fast idle adjustment screw.

Jon.

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Old 09-14-2020, 08:57 AM
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Dick Boneske Dick Boneske is offline
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There is no separate adjustment on a '66 center carb for fast idle. The idle speed adjustment is the screw that contacts the fast idle cam. It obviously affects fast idle and normal idle.

The only way, as Jon pointed out, is to get the choke to operate correctly. When the choke is closed, the fast idle cam needs to be on the highest portion of the fast idle cam. That's the first thing you need to confirm. If you find that is proper, note whether the choke is closing completely when the engine is cold and you set the choke by depressing the accelerator pedal one time. The length of the rod from the choke stove in the manifold is what controls whether the choke closes. If you have installed a spacer under the carb, this rod will be too short, and the choke will not close as it needs to.

If there is a spacer in place, I can supply a longer rod to correct this. PM me for more info.

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Old 09-14-2020, 09:21 AM
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Even if you do the correct adjustment on the rod to thermostatic coil for fully closed choke blade at cold engine, you still have to adjust the fast idle lever at the choke trip lever on the drivers side of choke blade shaft.
This is what lifts the fast idle cam to the high step.
Place idle screw on second step of cam against high step.
Gage between upper edge of choke valve and air horn casting, .095" +- .010".
Bend tang on fast idle lever to adjust.

HTH

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