# '64 tripower carb stud length



## 64since65 (Dec 11, 2019)

Anybody know why two of the carb mounting studs are longer on a '64 tripower setup and _where they go_? I bought a new set of studs and two of the twelve are longer than the rest. The ones I took off are all the same (longer) length. The carbs bosses are all the same width so it must be for some attachment. The current problem is that I don't know where to install the two longer studs.


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## Roger that (Feb 6, 2010)

Of all the original untouched tri-powers that I have seen for the GTO years the longer studs have always been on the rear carb, both of them on the passenger side.


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## Mine'sa66 (Oct 30, 2019)

Roger that said:


> Of all the original untouched tri-powers that I have seen for the GTO years the longer studs have always been on the rear carb, both of them on the passenger side.


Do you know why? I would have to guess it's to hold some sort of a bracket. But what? Is cruise control a possibility?


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## PontiacJim (Dec 29, 2012)

I was thinking the vacuum diaphragm that opened up the outboard carbs on the earlier tri power. Not sure where that got located or how?


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## Old Man Taylor (May 9, 2011)

The vacuum diaphragm was on the passenger side of the rear carburetor. It's been so long that I don't remember how it was mounted for sure, but it was probably on those two rear studs.


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## Roger that (Feb 6, 2010)

On 1966 tri-powers Pontiac used a special hollow threaded stud which was even longer than the 64-65 studs on the passenger side rear carb for manifold vacuum on A/C cars. This stud was capped off for non A/C cars in 1966. 64-65 A/C tri-powers did not obtain the vacuum from that location.

The secondaries vacuum canister was mounted on those longer threaded studs for automatic transmission cars.


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## 64since65 (Dec 11, 2019)

"on the rear carb, both of them on the passenger side."
Thanks. That's where I'll put 'em. Apparently that extra length won't be needed since the tri-power was changed to a mechanical advance in late '65.


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