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1st Gen GS lunges


Guest clamshells
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Guest clamshells

Goldie the Gran Sport is fine until I run the air conditioning then she lunges while stopped in drive.

I thought about never stopping but driving a Riviera without the AC on a hot day is out of the question.

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Guest clamshells
Look at the switch pitch system to the torque converter. May not be functioning.

arnulfo

Adjusted switch I now have The Click with ignition ON. I'll road test when it isn't 102 degrees ;-)

Vacuum leak.

A vacuum leak in the Air Conditioning vacuum circuit?

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A vacuum leak in the Air Conditioning vacuum circuit?

That entire switching unit in the console is nothing but a bunch of vacuum lines that open doors, etc. If in the off position, the vacuum to the switches / doors is shut off. When you turn on the air you're allowing vacuum into the assembly. If there's a loose/broken vacuum line anywhere in the system, you could have a problem.

Ed

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Guest clamshells
102 in the Bay Area?!

"The Bay Area" is a 40 mile radius north, east and south of the actual SF Bay. The East Bay heats up.

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That entire switching unit in the console is nothing but a bunch of vacuum lines that open doors, etc. If in the off position, the vacuum to the switches / doors is shut off. When you turn on the air you're allowing vacuum into the assembly. If there's a loose/broken vacuum line anywhere in the system, you could have a problem.

Ed

VERY TRUE! A vacuum leak creates a lean running motor which in turn will cause the Rpm's to be higher than normal. The biggest danger of a motor running lean is the higher running temps and the possibility of burning a hole in a piston.

Arnulfo

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Guest clamshells
VERY TRUE! A vacuum leak creates a lean running motor which in turn will cause the Rpm's to be higher than normal. The biggest danger of a motor running lean is the higher running temps and the possibility of burning a hole in a piston.

Arnulfo

So far so good running the AC. First improvement noted since SP operating correctly the car shifts in gear smoothly. As far as too lean IDK I checked all vacuum lines all is good. The idle adjustment screw (the big one in between the idle screws) is out about 5 turns.......is that normal?

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There should be two idle screws, one for each primary venturi. They're only to be adjusted when the throttle blades are fully closed. As the title implies, they're only good to adjust the idle. Normally they're out only about 2-1/2 turns from the bottom. Once you step on the accelerator, the idle circuits are of no consequence and no amount of turns in or out will matter.

The kick down switch has nothing to do with shifting. It only changes the angle of the vanes in the torque converter when the electric solenoid inside the transmission is engaged. That engagement takes place when the rod on the carburetor is plunged into the switch. Then two things happen, not both at the same time though, the vanes in the torque converter change pitch (angle) to high stall and the transmission is down-shifted. The other thing the variable pitch converter (switch pitch) has to do is shift the vanes to high stall when the car is idling. Once again, as soon as you apply the least little pressure to the accelerator, the vanes revert back to low stall. The purpose of the high stall at idle is to keep the car from creeping when there's pressure on the brake. The nailhead has enough torque that the car will creep if you don't keep firm pressure on the brake pedal. To overcome this, at idle the vanes go to high stall and not as much brake pressure is needed to keep the car from creeping. Little ol' ladies oughtn't drive torquey cars, they're not strong enough, or don't want to put forth the effort, to hold the car still at a stop light.

Ed

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Guest clamshells
There should be two idle screws, one for each primary venturi. They're only to be adjusted when the throttle blades are fully closed. As the title implies, they're only good to adjust the idle. Normally they're out only about 2-1/2 turns from the bottom. Once you step on the accelerator, the idle circuits are of no consequence and no amount of turns in or out will matter.

The kick down switch has nothing to do with shifting. It only changes the angle of the vanes in the torque converter when the electric solenoid inside the transmission is engaged. That engagement takes place when the rod on the carburetor is plunged into the switch. Then two things happen, not both at the same time though, the vanes in the torque converter change pitch (angle) to high stall and the transmission is down-shifted. The other thing the variable pitch converter (switch pitch) has to do is shift the vanes to high stall when the car is idling. Once again, as soon as you apply the least little pressure to the accelerator, the vanes revert back to low stall. The purpose of the high stall at idle is to keep the car from creeping when there's pressure on the brake. The nailhead has enough torque that the car will creep if you don't keep firm pressure on the brake pedal. To overcome this, at idle the vanes go to high stall and not as much brake pressure is needed to keep the car from creeping. Little ol' ladies oughtn't drive torquey cars, they're not strong enough, or don't want to put forth the effort, to hold the car still at a stop light.

Ed

The front carb isn't adjustable, the rear carb has 3 screws: 2 typical idle mixture + one large 9/16" hex plug in the middle.

post-98889-143142642506_thumb.jpg

Adjusting the SP Switch made driving the car much more enjoyable.

post-98889-143142642522_thumb.jpg

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The front carb isn't adjustable, the rear carb has 3 screws: 2 typical idle mixture + one large 9/16" hex plug in the middle.

[ATTACH=CONFIG]261349[/ATTACH]

Adjusting the SP Switch made driving the car much more enjoyable.

[ATTACH=CONFIG]261350[/ATTACH]

Mike, Sorting out the the SP function makes shifting from park into gear much smoother because the converter is in the high stall mode at a curb idle. Therefore the impact on the driveline is lessened. You should also feel what seems like a downshift when in high gear and depressing the throttle just short of the downshift detent. This is the converter switching from low stall into high stall.

The large brass screw in the center of the rear carb is an idle speed air bleed. This controls the volume of air entering the intake (throttle butterflyies are completely closed at curb idle on dual quad applications) and hence controls engine idle speed. The left and right mixture screws are for fine tuning the idle mixture after setting idle speed with the large brass screw.

If your idle speed is "hunting" it may be due to incorrect mixture settings, a vacuum leak, or the idle is simply too low to handle the extra load the AC comp is placing on the engine.

Tom Mooney

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Guest clamshells

Both of my dual quad cars run a little rough. I have sprayed brake cleaner on all the vacuum fittings, clamped all the vacuum hoses closed with no RPM or idle changes. I have adjusted the idle mixture screws according to the 65 Shop Manual Dual 4-Barrel Carburetors instructions on both cars countless times and they both have a mild case of the shakes.

Timing, dwell is dead on specs. Both cars have under 2K miles silent valve trains (cams to valves). I figure: The Nature of The Beast.

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Both of my dual quad cars run a little rough. I have sprayed brake cleaner on all the vacuum fittings, clamped all the vacuum hoses closed with no RPM or idle changes. I have adjusted the idle mixture screws according to the 65 Shop Manual Dual 4-Barrel Carburetors instructions on both cars countless times and they both have a mild case of the shakes.

Timing, dwell is dead on specs. Both cars have under 2K miles silent valve trains (cams to valves). I figure: The Nature of The Beast.

Make sure the throttle blades on BOTH carbs are completely closing.

Tom

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