Any Pontiac Tri-Power gurus here.

[JonW]

I’m looking at a ‘66 Star Chief Executive that the previous owner added Tri-Power to. I intend to use the car for touring events. Am i shooting myself in the foot with the TP? Would I be able to cruise at highway speeds on just the center carb?

[Barney Eaton]

That was the idea...... the secondary carbs do not kick in until the linkage mechanically opens them. 

I do not own one but grew up around several.... when they open it is full open so it is all or none.  

You would want to make certain the linkage is adjusted correctly.    You could also disconnect  the secondary carbs

but need to be aware that if you do not use them you will have stale gas setting in them.   You could also disconnect the fuel line or plug them

and they would just be decorative.   

I am sure there are experts out there that will correct anything I have wrong. 

[John Byrd]

JonW, I had a 66 GTO with the tri-power, and it worked perfectly and actually got fairly decent mileage if you kept the right foot under control. I did put new fuel lines and air filters on mine, but just adjusted everything carefully and used the car for a couple of years with no troubles.

[carbking]

That tripower needs to be inspected by someone familiar with tripower!

 

WHY?

 

Because there are some squirrels selling "reproduction tripower tops" and "reproduction tripower throttle bodies". The customer is then asked to visit their favorite junkyard, and acquire ANY Rochester 2-barrel, and use the "repro" parts to turn the junkyard piece into a "tripower" carburetor.

 

If that is the case, run, don't walk.

 

You can find carburetor casting numbers at this page from my website: Pontiac tripower specifications

 

Now, if the carbs are genuine, and the intake is genuine (not some aftermarket), the 1966 tripower worked fairly well. Fuel economy will be decent if you place an egg between your right foot and the footfeed, and don't break the egg!  

 

And my 1964 GTO with tripower would easily exceed most speed limits on the center carb only.

 

The tripower does not perform as well as the Carter AFB, but to many, the "eye candy" is worth the slight reduction in performance.

 

Jon

Edited May 12, 2022 by carbking (see edit history)

[Pfeil]

2 hours ago, Barney Eaton said:

That was the idea...... the secondary carbs do not kick in until the linkage mechanically opens them. 

I do not own one but grew up around several.... when they open it is full open so it is all or none.  

You would want to make certain the linkage is adjusted correctly.    You could also disconnect  the secondary carbs

but need to be aware that if you do not use them you will have stale gas setting in them.   You could also disconnect the fuel line or plug them

and they would just be decorative.   

I am sure there are experts out there that will correct anything I have wrong. 

The all or nothing is true of vacuum operated tri-power and not the progressive manual linkage. The term progressive linkage moniker tells the story of progressive opening to full throttle blade WOT operation. For street driving I would take the 65 version over the 1966 version. The 65 unit uses the smaller center carb for better mileage. Seat of the pants driving the only difference you'll feel is in the wallet.

[GARY F]

I own a 63 Grand Prix with correct tri-power.  Just dont put your foot in it and you can run on the center carb all day long. The last 3 digits on the manifold on my 63 is 275.  If you could post some pictures of the set up we could help a little more.

[JonW]

Good stuff here. Thanks for the replies. I now have some questions for the seller.

[rocketraider]

I THINK Tri-Power on 1966 full-size car was vacuum operated outboard carbs, but I know a lot were converted to mechanical linkage.

 

Look at left front of the intake manifold coolant crossover passage and see if there's a vacuum switch on it. The idea was to keep the outboard carbs from operating until engine coolant had warmed up.

 

Mechanical linkage cars had a blank-off plate in that location.

[Pfeil]

The brochure for the 1966 2+2 shows a picture of a 421 H-O tri-power taken from the brake master cylinder looking towards the front of the engine bay and the car in the picture has progressive linkage.

[carbking]

The Pontiac Master Parts Book shows nnn8857 vacuum motor as being used on 1966 as well as earlier Pontiacs with tripower. The vacuum motor (on front carb in 1966) was a part of the vacuum linkage. When vacuum was applied to the motor, the arm would open the front carb, and the front to rear rod would open the rear carb.

 

I have sold my 1966 dealer album, so cannot prove next statement; but memory says vacuum linkage on 1966 non-H.O. engines, and mechanical linkage on H.O. engines.

 

Jon

Edited May 13, 2022 by carbking (see edit history)

[JACK M]

I never drove one but a friend hated the vacuum operated linkage as it took a moment for it to unload.

[GARY F]

1 hour ago, JACK M said:

I never drove one but a friend hated the vacuum operated linkage as it took a moment for it to unload.

In 63 I bought a new 63 Catalina with tri power. My friends told me to get rid of it. One day I was running it wide open and then took my foot off the pedal and with that vacuum operated linkage it stayed wide open to long and I was standing on the brakes.  I went right down to the Pontiac dealer and bought the progressive set up. I have that now on my Grand prix.

[Piaras]

Uncle Tony Garage has a YouTube video explaining this system both vacuum and mechanical. Engine Masters also has a video on these systems in comparison to 4 bbl and dual quad set ups.

Pierre

[Pfeil]

On 5/13/2022 at 1:56 PM, GARY F said:

In 63 I bought a new 63 Catalina with tri power. My friends told me to get rid of it. One day I was running it wide open and then took my foot off the pedal and with that vacuum operated linkage it stayed wide open to long and I was standing on the brakes.  I went right down to the Pontiac dealer and bought the progressive set up. I have that now on my Grand prix.

Gary, I had the very same experience. In 1959 my dad ordered a S/O Catalina hardtop sport coupe with a 420"A" 389 Tri power with a HD Super HydraMatic. My dad raced it in AS/A. In 1961 we installed a progressive linkage kit from Royal Pontiac along with a Bobcat kit and a set of 1960SD big valve heads. I got my drag license in 1965 at the age of 14 and raced it in FS/A. In 1967 I got my regular drivers license. One evening after a Bible study class I was pulling out of the parking lot going home and there were about 25 of my classmates playing football in the parking lot. As I was pulling out of the parking space I depressed the accelerator pedal lightly with the wheels cranked all the way to the left to pull out of the space when the accelerator went to the floor and the car took off with guys jumping out of the way. That Catalina had so much torque the brakes wouldn't hold it back. Standing on the brakes, front wheels skidding and rear tires burning rubber I finally was able to climb up and cut the ignition switch. My dad and I finally found the problem the next day when after we exhausted all possibilities we brake torqued the automatic and the engine's left bank looked like the engine was going to jump out of the engine compartment, and of course the car took off again with my dad at the wheel. A broken left motor mount ( no safety hook) (no factory bulletins) caused the engine to torque up and WOT the throttle linkage. Ironically about two weeks later the very same thing happened to a friends 59, 348 tri-power Impala.

[GARY F]

Good story.