[Dick Boneske]

All the automatic '64 through '66 GTO's and big Pontiacs had a switch mounted between the center and rear carb for the transmission kickdown. These cars were built with vacuum-operated secondary carbs. When converting these setups to factory-style mechanical linkage, there is very little room for a switch in that location.

I believe '67 was the first year the switch was relocated to the firewall below the dashboard, but from '67 onward, Tripower was not an option.

On my son-in-law's '66 Tripower, we mounted the kickdown switch in the normal location, using the factory bracket and switch, but moved the slotted rod mechanical linkage to the front carb. Works great, but I don't like the strange looks we get from purists.

Note on the third picture, someone did squeeze the switch in with slotted rod linkage on a '66 setup. I spotted this at the 2013 Dayton Co-Vention.

Specifically, for a '65 big Pontiac, we want to provide a kickdown switch while using the "J" type center carb lever with slotted rod style linkage correct for a '65 Tripower setup. I have the original '65 switch and bracket, but cannot fit it to the setup with mechanical linkage.

Any ideas?

[60sstuff]

For a 1966 GTO with Factory Tri-Power and Automatic transmission.

The transmission kick down switch was mounted inside the car above the fast pedal as shown below in my 66.

Only 64 and 65 GTO had that switch mounted at the “LH rear of center carb”.

Chris.

[Jonsie]

Dick, I was able to fit the linkage properly connected to the rear carb, with the carb mounted kickdown switch operable. Tight fit, but it is doable. Similar (not identical) to your 3rd pic, the Dayton car. My car is a '65 Cat, but shouldn't the set-up be identical with either a '65-'66 A or B-body?

[Jonsie]

60sstuff- I should have read your post before replying. I did not know '66 set-up was different from '65's.

[Dick Boneske]

Thanks for the information. Has anyone used a different switch/bracket to better fit with mechanical linkage?

[Jonsie]

I'll try to post some pics later today

[Jonsie]

Here are the pics of my set-up. I moved the slotted rod to the outside of the plunger vs. inside. Rod just clears the switch itself. Probably "not correct" but it works. And the large aircleaner clears the mechanism fine.

[Dick Boneske]

Thank you, Jonsie. I'll make that work on this one, too.

[2+2=421]

I wonder who sells that underdash bracket and kickdown switch? Does anyone know or have one?

[Tom Vaught]

Jonsie, Great Pictures.

My only concern with your linkage set-up ism the offset of the "pulling link" from the swedged center shaft (where the Brass Extension for the carb is attached by Rochester).

I have seen those Brass Extensions pulled off the carb when the gas pedal assy had more travel vs the carb extension travel. This was with the 64-65 Cable type gas pedal (GTO Style). Have to think that the solid rod type pedal on the big car linkage could generate some serious force on the center carb extension arm and potentially over time pull the arm and swedge right off the throttle shaft. Might want to check for that situation with a friend and make sure there still is a bit of carb travel left. The throttle blades not being perfectly vertical makes NO DIFFERENCE in the air flow thru the carb.

Tom V.

[Jonsie]

Tom V.....good point. Haven't yet had the car on the road, 6 years in the making, getting ready to have it registered. I will surely check out the rod travel beforehand. Thanks for the tip.........
Question: does the offset put more pressure on the extension arm than the 'correct' factory set-up (inside the kickdown sw)?

[Tom Vaught]

Originally Posted by Jonsie

Question: does the offset put more pressure on the extension arm than the 'correct' factory set-up (inside the kickdown sw)?

I have replaced the Center Carb "lever arm" on a couple of 1964 GTO Service Package linkages (like Dick B sells) and I have originally on my car that was put together by the Rochester Products people many years ago. Dick B's 64 Carb Linkage is first class stuff.

That being said, if a owner does not check stuff you can have the lever arm either get loose and wobbly or get pulled completely off the shaft.
The 64 Service Package kit has the carb return spring connecting point pretty far out from the shaft swedge. Might work great if the pedal hits the floor before the carb lever contacts the carb base stop. If the other way around, no issues.

In 1965, Rochester Products did two mods to the linkage.
They moved the linkage to the inside vs being on the outside of the lever and they made the linkage a "Trapped Set-up". Now you could not install the linkage wrong and have the
Tube and Plunger Rod installed incorrectly. If you do that there is a possibility that the rod would drop down, hang in the exhaust cross-over and keep the end carbs partially open even after you left off the gas. An ACCIDENT waiting to happen. The 65 Linkage fixed that.

Sadly there are some advertising pictures even in 1966 magazines that show the Tube and Plunger linkage installed backwards.

Tom V.

[Dick Boneske]

Tom,

Your concerns of incorrect adjustment/tweaking of the throttle linkage and the danger of loosening the swaged throttle arm mounting is very real. At least half the Tripowers I restore come to me with the lever loose on the shaft--sometimes both the center carb and the rear carb.

On a big Pontiac, the linkage from the accelerator pedal to the center carb is easily adjustable to provide full throttle opening, but no destructive pull on the carb lever as the accelerator pedal reaches the floor. The rod is readily adjustable to accomplish this.

On a GTO, the cable that operates the center carb lever is not adjustable, except for the '64 GTO cable with its three holes for the throttle stud. However, the throttle cable bracket on all years' GTO's does allow some movement (about 1/8") back & forth to help with the correct setting. In some cases, it is necessary to bend the bracket to accomplish the desired setting.

The best way to ensure that the setting is correct is to have a second person hold the pedal to the floor while you observe that the throttle is fully open by looking at the throttle stop on the center carb base, but also that there is no pedal travel pulling on the carb lever beyond open throttle. Failure to set this properly will result in loosening or damaging the center lever attachment to the throttle shaft.

With the slotted rod or rod & tube linkage to from the center carb to the rear carb, it is equally important to adjust the length of the linkage rod to provide full throttle opening of the rear carb without undue pressure on the rear throttle arm.

The long rod that links the rear carb to the front carb an the passenger side also must be adjusted to center the rod end in the front carb lever's oval hole. This is done by bending the rod in the center to shorten it or bending it straighter to lengthen it.

I've attached some pictures showing the various features discussed above, and even though they don't show point-by-point instructions, they may help you understand what's involved.

[2+2=421]

Can you buy the bracket anywhere ? I think this will work on my 66 2+2

[Dick Boneske]

Originally Posted by 2+2=421

Can you buy the bracket anywhere ? I think this will work on my 66 2+2

I have quite a few of the switch brackets for '66 setups. PM if you need one.

Be aware that the bracket needs to be tweaked and the linkage moved outboard of the levers to clear the switch.

Here's how one guy did it on his '66 big Pontiac. He used the original switch bracket and left the mechanical linkage inside front lever, but moved it outside on the rear carb.