[Doug]

I have a center carb (without a tag) from 66 tri-power builder set. It may be a rebuild carb and I would like to know if the carb is ok to use on a tri-power. Some of the numbers on the carb parts are:

bowl- 7035175
bottom of bowl- 31
throttle plate base- 19575 (underside)
cluster- 16266
top- 7031587 (underside above float)
choke tab- 26469
choke rod- 19524
jets- .060

Thanks for observations and comments!

[mike w]

If you could post a picture, or two, it would really help.

Mike Wasson

[Doug]

Mike,

here are a couple pics--------Thanks! (loosely assembled)

[61-63]

Cobbled up center carb with '66 base and airhorn and an earlier vacuum secondary accelerator pump arm it looks to me.

[Tom Vaught]

Accelerator Pump Arm is same arm used on Vacuum Secondary 1966 Tri-Power Carbs.

Tom V.

[61-63]

I didn't realize they still used vacuum secondaries in '66 shows what I know about tripowers.

[mike w]

The throttlebody is from a 2bbl Pontiac between 1959 and 1967. This is evident, because there are 3 holes on passenger side for the choke cup that was mounted down there. One hole supplies vacuum for the pull-off piston and the other 2 are threaded #8 for screws that attach the cup. This throttlebody could be used if the holes were plugged, primarily the one that supplied vacuum to pull-off piston.

If the airhorn has a mount for the vacuum choke pull-off, it is from a 68 or 69 Pontiac 2 bbl.

One more thought.....your throttlebody does not have a vacuum source for this pull-off, which the correct 66 throttlebody would have.

Hope this helps.

Mike

[Doug]

Thanks for all the replies!

FYI: I made an error in the numbering of the float bowl. It should read 7031575.

TOM, about the accelerator pump arm--why is the lever on it is shaped with the “fingers” on it. Did those fingers activate some other piece? (Just curious)
Can I change out the pump arm for the one in the picture below?

This ad is in the current AMES big car catalog:

PN232FC 1959-66 Tri-Power Vacuum Actuator (RE)......... 57.00/ea.
PN232FC is the accelerator linkage vacuum actuator. It is not used
with mechanical (progressive) style linkage. Fits all 1959-64 tri power
and 1965-66 tri power with automatic transmissions.


MIKE, The hole in the throttle body for the vacuum source for the choke cup is plugged off and the 2 bolt holes are dead end holes. Since I am using a hollow carb mounting stud for distributor vacuum, can’t I use the screw-in nipple vacuum fitting on the throttle body as a vacuum source for the vacuum choke pull off?

I assume that other than a 68 or 69 carb (with the airhorn choke pull off mount), the only other large diameter carb with the airhorn choke pull off mount is a 66 center carb. Is that correct? Would the bowl of a 68-69 have a number of 7031575?

Thanks again!

[Tom Vaught]

Originally Posted by Doug

Thanks for all the replies!

TOM, about the accelerator pump arm--why is the lever on it is shaped with the “fingers” on it. Did those fingers activate some other piece? (Just curious)
Can I change out the pump arm for the one in the picture below?

Reply: Very easy to change out the Vacuum Secondary pump arm for the mechanical linkage pump arm. No more than a 15 minute job if you have the other Mechanical Linkage Pump Arm.

This ad is in the current AMES big car catalog:

PN232FC 1959-66 Tri-Power Vacuum Actuator (RE)......... 57.00/ea.
PN232FC is the accelerator linkage vacuum actuator. It is not used
with mechanical (progressive) style linkage. Fits all 1959-64 tri power
and 1965-66 tri power with automatic transmissions.

Reply: The carb could be a very good replacement Tri-Power Center Carb with changing a few parts for appearance sake. Many have converted 64 and 65 Center Vacuum Activated Switch set-ups to mechanical Linkage and left the Vacuum Switch Actuator lever on the carb. You are not trying to pass off the engine as being built with the Tri-Power on the assembly line anyway.

The Arm has three levers. The lower arm raises and opens the vacuum switch mounted on the float bowl screws bracket when you reach a given throttle position. The middle one positively vents the vacuum in the line to the rear carb diaphragm when you close the throttle. The top lever opens up the carb vent for the bowl.


MIKE, The hole in the throttle body for the vacuum source for the choke cup is plugged off and the 2 bolt holes are dead end holes. Since I am using a hollow carb mounting stud for distributor vacuum, can’t I use the screw-in nipple vacuum fitting on the throttle body as a vacuum source for the vacuum choke pull off?

You asked Mike, but what you are proposing for the carb vacuum source for the choke pull off would work. The line just reads manifold vacuum.

Thanks again!

Tom V.

[Doug]

Tom,
I looked back at this old thread and saw the pictures of the 66 vacuum linkage setup.
http://forums.maxperformanceinc.com/...d.php?t=756570

Attached are a couple pictures from post #4 in the thread that show the basics of the setup.

Thanks for the info!

[Tom Vaught]

Unfortunately the California Evap System Hose has the lever for the Vent/Accelerator Pump Arm covered up but it is there.

When you triggered the system this is the vacuum flow:

1) Out of the vacuum can to a "Vacuum Tee" One side of the "Tee" received vacuum thru a checkvalve thru the hose going to the front carb base. That Vacuum "Charged up" the vacuum can when you were cruising down the road. The second nipple of the 3 vent to that check valve.

2) The third nipple of the "Vacuum Tee" went to a Thermostatic Temp Switch on the front of the Manifold Water Cross-over.

3) From the Thermostatic Temp Switch vacuum traveled thru a metal connection pipe to the Center Carb Vacuum Activation Switch.

4) The Center Carb Vacuum Activation Switch had three nipples on it too.
a) Supply source to the switch b) supply to the Rear vacuum Diaphragm c) Vent to the front carb airhorn.

5) So once the Center Carb Accelerator Pump Lever opened the Vacuum switch Vacuum traveled to the Rear Diaphragm and opened the End Carbs.

6) When the Driver released the Gas Pedal, the Center Carb Accelerator Pump Lever switched the signal on the Center Carb Vacuum Switch from a supply mode to a Vent Mode. Vacuum from the Rear Carb Diaphragm vented back into the front carb airhorn.

7) This process took time vs the Mechanical Tri-Power Linkage and people wondered if the engine was ever going to close the secondary carbs. One reason why a LOT of people switched to the Mechanical Linkage parts, Doug.

Hope that helps.

Tom V.