Synchronizing carbs on a Tri-Power 4-spd 389
 

How difficult is it these days to locate a shop that would have the old school knowledge to properly tune and dial in a 3-duece set-up?

Not sure what you mean by dial in.Correct pontiac tripower carbs really dont need much except for jetting.The front and rear carbs are just dump carbs.No AF adjustments on them.The important thing is that the throttle blades are shut so the F&R are not pulling fuel at idle.Mike Tripower can rebuild your carbs and be ready to just bolt on and go.The manual linkage allows to run on the center carb only until you advance the throttle to kick in the F&R.If the setup is still using the vacuum linkage you will want to replace it with the manual linkage.Good luck with your project.Tom

Tom, appreciate the quick response. Always thought the Tri-Power set-up was finicky and a PIA to get right. But, from your desription its pretty straight forward. Yes, dial in was a poor choice of words. Window shopping for a '66 and spotted one about 3.5 hrs. from here with the this set-up. Dealer wants 39K. Driver quality. Its gold with black vinyl top, black interior, 4-spd, post car. I suppose the money isn't to far fetched, considering these are becoming harder and harder to find. You say....
Thanks

Just be careful when buying a tripower.Many sellers dont use original tripower carbs!Tom

Was Tri-Power a better performance builder than the 4-barrel for its time?

Btw, who did Pontiac source out to produce these 2-barrel carbs?

In 1964, I bought a GTO with a single AFB.four barrel. I added Doug's three tube headers, modified the distributor advance curve, added Hoosier slicks. Before these mods, the car ran 14,[email protected] mph. . After the mods, the best I could do was 13.70's. I bolted on a '62 big car Tri-Power and, after further tweaking, got a best of [email protected] mph.
So, I believe that Tri-Power over the AFB gains about 0.3-0.5 seconds in a quarter mile run.. The Quadrajet is a better four barrel carb, that comes close, but does not match the performance of a Tri-Power. I've run a 850 Holley, AFB, and a Quadrajet on the same engine, same drag strip. The 850 Holley ran very close to the Tri-Power, but was terrible on the street for throttle response and fuel usage.

Carbs are made by Rochester.

I agree with Dick, as does PMD. The four barrel engine was the base engine, rated at 335 HP, with the tripower the optional upgrade rated at 360 HP (1965 GTO ratings).

K

What model is the car? Have you confirmed it is what the dealer has it listed as? Data Plate, VIN, PHS?

If you have a moment...please Google MapleMotors.com. Click on inventory there you will find the '66 GTO (post) (gold w/black vinyl top) along with video...what is your initial impression of the car? Apparently, the business model doesn't allow for room to negotiate price.

The 4 barrel and tripower engines also used different cams so carb to carb it isn't exactly an apples to apples comparison. However, Dick's comments above surely indicate the advantages of the tripower over a 4 barrel all other things being equal.

The only problem we've ever had with the tripower was the wrong body-to-base gaskets. The outboard carbs need a way to bleed off some air so vacuum doesn't pull them open before they are needed, the correct gaskets provide this air bleed. They were harder to find. We originally had a set used to rebuild the carbs but they sat around so long during the restoration that they dried out and shrank causing big vacuum leaks. Once good correct gaskets were used, it has run great with no fiddling. Ours had all the correct original carbs so we didn't even mess with the jets, just rebuilt them. Once good correct carbs are rebuilt, about the only adjustments are idle screws (center carb) and the mechanical linkage to determine when the outboard carbs should start opening up. If the linkage is not adjusted correctly it can open the outboards too early or too late. Pretty easy to test and adjust though. We had a set of original linkage used the last time the car had been running and matched the adjustment to that and honestly we never messed with it again, it worked great from the beginning following the restoration.

https://www.maplemotors.com/inventory/5321/detail.php

Pretty car; presents well. I didn't see anything glaringly obviously wrong. I appreciate them showing all the little nicks and scratches. Probably nicer than any of my stuff.

Dipstick location is a bit weird. Perhaps correct for A/C? Looks like an air conditioning equipped car with the compressor removed.

Cooper Cobra tires get a lot of disdain in the high end community (but since they are blackwalls that mitigates the hate a bit, I presume).

K

Keith, appreciate your comments. Unfortunately, if I purchased this car I would'nt have allot of extra money to throw at. But I would own a '66 GTO...just to add to the list of other muscle cars I have bought and sold in years past.

It's a want not a need. But they are all for that matter. We're nothing more than caretakers.

I don't believe that Goat will sit on their car lot very long.

BTW, I just had to go back and look closer at the engine bay passenger side firewall and just like you pointed out it was born an A/C car...still has the compressor mounting bracket. You guys are the best.

Thanks,
George

Nice car but engine needs some help.

Smoke from oil filler cap means shot piston rings.

Smoke from passenger side tail pipe only means shot head gasket.

Rear carb has no fuel line to it, could be flooding issues that caused the smoke issues above.

First let me say tripower carbs are not difficult to rebuild if necessary. When I have had issues in the past, I would take the Front and rear carbs off. I made block off plates for the manifold and ran the car with temp. rubber fuel line right to the center carb. I have found evidence of BAD fuel in the float bowl. Once found a bad float.(fuel in the brass float).
If the car runs great by doing this, you know it is a problem with the end carbs.
Mike @ pontiactripower.com has made videos of every aspect of our carbs.
John @ pontiactripowers.com has any part and kits for our carbs.
Dick Boneske (text 9204501040) "Bonestock Goats" also has the same sevices.
All Great guys to deal with.
thecarburetorshop/pontiac tripower specifications.com lists all the correct part numbers for the carbs.

Appreciate the hard facts and observation. This is why I called on the team of experts...that own and drives these cars. Besides, the things you point out...blower motor and or fan relay and heater core are probably shot. Replacement A/C compressor BIG bucks. Suspect rear window glass leaking into trunk floor. Those butresses on these cars were a cool styling feature but prone to many problems as were vinyl tops later in life. Not to mention an entire repaint $$$$$$$$$ and who knows how much bondo is yet to be discovered.

It's the pure definition of a 20 footer.

I've been down this road before on a 55 Chevy and I've been the poor SOB that got suckered in. An expensive pill to swallow.

All in all asking 39.9K with zero compromise is a NO GO for me.

this is the one common false thing spread about tripower set ups. They are not hard to dial in as they run off the center carb 75% of the time just like your moms wagon did... the end carbs essentially behave like the secondaries on a 4 bbl adding air and fuel. Center carb has choke, idle circuit, and power valve. End carbs do not have idle circuits, choke, or power valve. This is why many TP dont work well if someone has unwittingling swapped in the non TP carbs.

once you learn how to break up what the parts of the set up do its easy....