TQ Primary Throttle Shaft Bushings

[73LemonTwist]

Well, the car is tucked away for a winter sleep and I have been thinking about next year's projects on it. I have decided to install bushings on the primary throttle shaft of my 6319SA Thermoquad (small bore primary version). This past summer I was noticing a periodic whistling sound that could be changed/eliminated by repositioning the primary throttle shaft. The carb has over 80,000 miles on it. The O2 readings on the passenger side bank of cylinders is unstable at idle.

So a couple questions for you carb folks;

1) Are the diameters of the primary and secondary shafts the same at 3/8" or is the primary shaft 5/16"? (I would measure it if I had access to the car but I don't). A friend measured his large bore TQ and both shafts are 3/8". Don't know if the small and large bore carbs use the same shaft sizes.

2) There appear to be two different styles of tool to cut the throttle plate for installation of the bushings.
a) drill bit type with a 3" pilot section that then steps up to the 7/16" diameter of the bushing.
b) reverse cutting 6 point reamer with a long pilot shaft on it. You have to grab the 6 point portion of the reamer with your drill to turn it.
Any thoughts on which tool works better and is most reliable to do a good job?

3) If the teflon is worn off the shaft significantly, does it matter given the bushings will be oil impregnated, or should one get the shaft recoated?

4) Any tips, or hints, from those that have done this job? I only have one chance to do this right.

Thanks all...

 

[GTX JOHN]

I always have a carb rebuilter do it.

 

[MoparLeo]

It tells you a lot if someone is asking how to machine something.
Should probably leave it to a pro. You only get one shot at it and if it goes bad, you're done.
A carb restorer who does this for a living has the experience, tools and proper parts to get the job done right.
If he screws up, it is on him to fix.
"do what you do, don't do what you don't do" A good creed to follow. The only way to buy experience is to pay someone who has it...

 

[Fran Blacker]

Woodruff Carburetor did bushed 3 Holley base plate throttle shafts for me $45 each. 1 week turn a round.

 

[72sunroof]

Well, the car is tucked away for a winter sleep and I have been thinking about next year's projects on it. I have decided to install bushings on the primary throttle shaft of my 6319SA Thermoquad (small bore primary version). This past summer I was noticing a periodic whistling sound that could be changed/eliminated by repositioning the primary throttle shaft. The carb has over 80,000 miles on it. The O2 readings on the passenger side bank of cylinders is unstable at idle.

So a couple questions for you carb folks;

1) Are the diameters of the primary and secondary shafts the same at 3/8" or is the primary shaft 5/16"? (I would measure it if I had access to the car but I don't). A friend measured his large bore TQ and both shafts are 3/8". Don't know if the small and large bore carbs use the same shaft sizes.

2) There appear to be two different styles of tool to cut the throttle plate for installation of the bushings.
a) drill bit type with a 3" pilot section that then steps up to the 7/16" diameter of the bushing.
b) reverse cutting 6 point reamer with a long pilot shaft on it. You have to grab the 6 point portion of the reamer with your drill to turn it.
Any thoughts on which tool works better and is most reliable to do a good job?

3) If the teflon is worn off the shaft significantly, does it matter given the bushings will be oil impregnated, or should one get the shaft recoated?

4) Any tips, or hints, from those that have done this job? I only have one chance to do this right.

Thanks all...

I did it on 2 thermoquads
I used these bushings
https://www.carburetor-parts.com/bushing-22-83.html
I had gotten a kit with the drill but this was 11 years ago.
This one will work
https://quadrajetparts.com/carburetor-bushing-installation-throttle-shafts-quad-p-886.html
Take it slow and use a drill press if possible.
Remember to stake the throttle plate screws after install.
Take a lot of pictures
The Teflon wear will not affect anything.
While doing that also remount the fuel wells with jb weld marine.

I started my car up after sitting over a week in about 10 seconds
No air or fuel leaks.

 

[Charger 770]

I did it on 2 thermoquads
I used these bushings
https://www.carburetor-parts.com/bushing-22-83.html
I had gotten a kit with the drill but this was 11 years ago.
This one will work
https://quadrajetparts.com/carburetor-bushing-installation-throttle-shafts-quad-p-886.html
Take it slow and use a drill press if possible.
Remember to stake the throttle plate screws after install.
Take a lot of pictures
The Teflon wear will not affect anything.
While doing that also remount the fuel wells with jb weld marine.

I started my car up after sitting over a week in about 10 seconds
No air or fuel leaks.

Done my TQs shafts the same way - i used the ream and flipped around in the drill so that the rest of the reamer's shaft could be used as a guide in the base.

I had some stubborn throttle screws so when reinstalling them I used a little JB weld along with the punch.

No brainer and works great !