# TRI POWER



## jedi (May 18, 2016)

Just wondering what the procedure for setting the mixture screw on the centre carburator?
Thinking turn it all the way in then back out a turn and a half, would that be a good starting point?

Thanks


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## GTOTIGR (May 3, 2020)

Hi Jedi,

The recommendation I’ve been given by the pontiactripower.com team Mike and John is to turn out 1.75 to start. Adjust from there depending upon how you car idles on the road. Mine required adjusting to between 2.25 and 2.50 turns out.








Pontiac Tripower


Pontiac Tripower



pontiactripower.com





They offer a DVD that is helpful.


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## JesseLyon (Sep 13, 2020)

jedi said:


> Just wondering what the procedure for setting the mixture screw on the centre carburator?
> Thinking turn it all the way in then back out a turn and a half, would that be a good starting point?
> 
> Thanks


You mean mixture "screws" (plural) right? Theres two of them. Yes, Ive been told turn them clockwise all the way in, and then 2 full turns out counterclockwise for both as a good place to start, and then adjust from there in small increments until you get best vacuum/smoothest idle. Make sure you wait until car is at full operating tempurature, and choke is open, before adjusting

The screw on the drivers side is also very hard to get at, I found a tiny electronics flatheard screwdriver was the only way I could reach it. I tried a flexible screwdriver extension, but it was too wide to get underneath the brake booster vaccum hose...









HOHXEN 3-Pieces 30CM Flexible Socket Extension Bar Set 1/4" Drive 11" 8" 6" Flexible Extension Drill Bit Holder for Screwdriver(Flexible Socket Extension) : Amazon.ca: Tools & Home Improvement


HOHXEN 3-Pieces 30CM Flexible Socket Extension Bar Set 1/4" Drive 11" 8" 6" Flexible Extension Drill Bit Holder for Screwdriver(Flexible Socket Extension) : Amazon.ca: Tools & Home Improvement



www.amazon.ca


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## JesseLyon (Sep 13, 2020)

jedi said:


> Just wondering what the procedure for setting the mixture screw on the centre carburator?
> Thinking turn it all the way in then back out a turn and a half, would that be a good starting point?
> 
> Thanks


Also, this guy has some good videos on his YouTube channel for setting up tri-power carbs...


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## Jetzster (Jan 18, 2020)

JesseLyon said:


> You mean mixture "screws" (plural) right? Theres two of them. Yes, Ive been told turn them clockwise all the way in, and then 2 full turns out counterclockwise for both as a good place to start, and then adjust from there in small increments until you get best vacuum/smoothest idle. Make sure you wait until car is at full operating tempurature, and choke is open, before adjusting
> 
> The screw on the drivers side is also very hard to get at, I found a tiny electronics flatheard screwdriver was the only way I could reach it. I tried a flexible screwdriver extension, but it was too wide to get underneath the brake booster vaccum hose...
> 
> ...


Heres a skinnier one just for GM carbs


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## jedi (May 18, 2016)

Thanks A Lot,

I just look and I do see the second adjustment screw, makes sense it’s a two barrel carburetor 

Again Thanks


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## JesseLyon (Sep 13, 2020)

Jetzster said:


> Heres a skinnier one just for GM carbs
> View attachment 143101


I knew there had to be a better way! Thanks, picking one of these up asap.


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## BearGFR (Aug 25, 2008)

For a "starting point" as you said, any setting that's good enough for it to warm up and keep running is fine. I'm assuming you're not going to leave it there, but will then use a vacuum gauge to get it 'right'.

Bear


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## Gtowally (Jan 19, 2019)

Jetzster said:


> Heres a skinnier one just for GM carbs
> View attachment 143101


Where did you find that screwdriver for that price? I just looked it up on Amazon and its listed at almost $35.00. Thought I’d like one in my toolbox, but jeeeess what a difference In price


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## Jetzster (Jan 18, 2020)

Lisle 55250 tool still there $11.36
and there’s at least two other brands as well
all 3 are $9-$11


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## Machinest-guy (Jul 19, 2019)

Good morning, the mixture adjustment screw needs to be where it provides best operation. When the carb set was new maybe 1-1/2 to 2 turns out was correct. But now much different fuel and sometimes additional air flow from wear and leaks often makes that value unusable. The DVD video by Pontiac Performance is quite good explaining this issue. I use a tool from MAC TOOLS number "CA-80" to adjust my center carburetor. I believe, after owning dozen of carburetor adjusting tools and using many like those shown above,









this one works easier and faster. It has a right angle gear drive which is narrow enough to clear the power brake fitting and an outer ring to hold the tool on the screw head. Best of luck in this adventure of adjustment. Ladd


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## Montreux (Mar 8, 2009)

Does it run? I always start by equalizing the left and right screw. Turn each screw in until it is lightly (Lightly, LIGHTLY) bottomed, counting the turns as you go. Average these and set both screws to the same number. 

If the average is outside of 1-1/2 to 3 turns, adjust it to this range. 

Starting 1-1/2 turns out is probably at the lean end so your adjustments will involve turning the screw out 1/2-1/4 turn at the time. As you get the mixture closer to ideal, the idle speed will come up. If necessary, adjust the idle speed, then tweak the mixture again. Make sure you are on the CURB idle, not the FAST idle screw. Fast idle screw is the one that contacts the fast idle cam. (This is a good time to verify that the choke is fully open, and the fast idle screw is not touching the cam.)


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## jedi (May 18, 2016)

Thanks for the replies,

I bought a real long skinny slotted screwdrive, so thin you could easily bent it

I turned each adjustment screw in until the engine stumbled and then backed them out 1/2-3/4 turn

Thanks Again
Jedi


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