# Tri power carbs!



## BuckHowie (Oct 1, 2021)

I’m a newbie at posting.when I go to start my 1965 gto 389 engine tri power it starts on the dime no pumping of the gas pedal when it’s cold. When it’s hot when I stop the car and start it right away it still starts on the dime . But when I wait a few minutes after I’ve stop it takes forever and a day to start . Is there anyone out there that can help me . Thanks!


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## Jetzster (Jan 18, 2020)

If I recall some have said that sometimes heat can affect certain types of fuel in the carb bowls causing some slight boil-over after sitting abit, causing difficult starting , the solution was getting phenolic heat spacers for under the carbs from the Tri-power people, others may chime in


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## Lemans guy (Oct 14, 2014)

Yes agree with Jetstar, you have “Heat soak” today’s gas has a lower volitily, that is boiling point than 1960’s gas, and it was a problem then as well. Some period cars had carb cooling fans even then. First fix is a phenolic spacers from Tri power guys.

Remove a hood blanket if you have one, they are not needed and they trap het after shutdown. Use pure gas if you can it has a slightly higher boiling point.

Refiners change to winter blend gas in the fall, it has a lower boiling point than summer blend so it fires in cold weather.

I use a couple of ounces of Stabil Marine 360 in a full tank as I believe it does help reduce the volatility a little bit. Open the hood after stopping if at a car show to help cool it off. Carb cooling fans can be added.

Phenolic spacers are the best first step.


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## Sick467 (Oct 29, 2019)

Here's a couple things to look for when it comes to a heated up engine bay and fuel issues...

1.) Mentioned above... the hot carbs are gassing off the fuel in the bowls. +1 on the phenolic spacers.

2.) The gassing off may also be occurring in the fuel line/s going to the carbs. Traditionally known as vapor locking and usually gives problems while running, but may also add to fuel starvation at the carbs in your case.

I would recreate the scenario you are having. Get the engine up to running temps, shut it off, wait the amount of time you are witnessing the problem...and then give the carbs a bit of a squirt of gas and try starting it. If it fire quickly (regardless of if it stays running), this would prove that the hard start is due to no fuel in the carbs.

I am not familiar with the 6 pack set-up, but you may be able to witness fuel coming (or NOT) from the accelerator pump/s. An alternative to the above would be to recreate the scenario, remove the breather/s, look into the carb/s and see if any fuel is being squirted when the throttle is pumped. No fuel means the carbs have dried out.

*EDIT:* the above two tests would only help with a fuel starvation problem, but not the "heat soak" problem LG mentions. This type of scenario is more prone to flood the engine.

Remembers that you are dealing with a hot engine AND gasoline...be extra safe!!!


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## BuckHowie (Oct 1, 2021)

Thank


Sick467 said:


> Here's a couple things to look for when it comes to a heated up engine bay and fuel issues...
> 
> 1.) Mentioned above... the hot carbs are gassing off the fuel in the bowls. +1 on the phenolic spacers.
> 
> ...


Thanks I was told on tri carbs only the middle carb is the one you run on until you punch it or excelorate .


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## BuckHowie (Oct 1, 2021)

BuckHowie said:


> Thank
> 
> Thanks I was told on tri carbs only the middle carb is the one you run on until you punch it or excelorate .


I will try anything thanks.


Lemans guy said:


> Yes agree with Jetstar, you have “Heat soak” today’s gas has a lower volitily, that is boiling point than 1960’s gas, and it was a problem then as well. Some period cars had carb cooling fans even then. First fix is a phenolic spacers from Tri power guys.
> 
> Remove a hood blanket if you have one, they are not needed and they trap het after shutdown. Use pure gas if you can it has a slightly higher boiling point.
> 
> ...


thanks!


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## BuckHowie (Oct 1, 2021)

Lemans guy said:


> Yes agree with Jetstar, you have “Heat soak” today’s gas has a lower volitily, that is boiling point than 1960’s gas, and it was a problem then as well. Some period cars had carb cooling fans even then. First fix is a phenolic spacers from Tri power guys.
> 
> Remove a hood blanket if you have one, they are not needed and they trap het after shutdown. Use pure gas if you can it has a slightly higher boiling point.
> 
> ...


Thanks I will buy some spacers I do run 94 octane.


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## Lemans guy (Oct 14, 2014)

Best way to start a heat soaked carb,….say after 15 to 20 minutes sitting engine off, is to slowly press the pedal to halfway down and then crank. What happens when you Heat soak is your intake is flooded with fuel, it has boiled from the carb bowls.

Halfway down adds more air to lean the mixture, and thereby start, then the fuel pump will fill the bowls again. The carbs may be half empty, so if you pump more fuel in you will be adding to the flooding condition.Heatsoak is a flooded intake, so resist pumping more additional gas in.

Abree with sick467 on wrapping the fuel lines


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## Sick467 (Oct 29, 2019)

LG, Are you saying that the fuel in the heated carb ends up in the intake causing a flooded situation? I am afraid I thought the fuel was vaporizing and disappearing into and through the air cleaner leaving the engine starved for fuel.


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## BuckHowie (Oct 1, 2021)

Sick467 said:


> LG, Are you saying that the fuel in the heated carb ends up in the intake causing a flooded situation? I am afraid I thought the fuel was vaporizing and disappearing into and through the air cleaner leaving the engine starved for fuel.


No it has a hard time starting when it’s warm when left for say couple of minutes , but if you shut it of when warm you start it immediately it starts perfect when your driving every thing from idling to accelerating it’s excellent. just starting when left hot or warm your cranking it a lot to start.


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## Lemans guy (Oct 14, 2014)

Sick yes that is right the gas “Percolates” like in a coffee pot and it flows up the main carb wells and down thru the idle circuits and jets and it puddles in the bottom of the intake, some of it vaporizes in the hot intake, but there is so much that it is too rich to fire. It does not boil away after 15 minutes.

Now when you turn it off at home after a drive, it does the same thing, but since you leave it a week, that gas in the intake then slowly evaporates. But now you are staring with a choke and if you have just a small amount of fuel in the bowls two pumps to set the choke on a cold engine will fire it up.


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## Lemans guy (Oct 14, 2014)

Heat soak floods the intake, your symptoms are exactly that. The reason it starts immediately when warm is that the Heat soak has not yet occurr and your intake is full of a correct mixture of vaporized gasoline. So instant start. When it starts right up that is from gas vapors laying on top of the valves, in the right mixtures of air and fuel.

When you shut off the engine within 10 minutes those carb temperatures are very hot and it starts to percolate and boil the gas in the bowls, it floods the carb circuits and down to the intake. So now you are flooded and won’t start.

In addition once it won’t start we start pumping the pedal, and if any remains at all in the bowls, we add more gas to the already flooded intake.

when starting immediately after turn off hot do not touch the pedal. It should have plenty of vaporized gas in the intake to start. After 15 minutes if you are “Heat soaking” slowly push pedal to halfway down and crank, it will lean it out and blow the rich mixture thru. It will run rough for a minute and then stabilize once the excess fuel clears


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## Lemans guy (Oct 14, 2014)

Gas fumes are heavier than air, they sink they do not rise. That is why your hot water heater in the garage sits on 2 cinder blocks. So the pilot light will not ignite a small gasoline spill.

The gas will fill every inch of space on the floor before it rises. Your intake is the same the gas vapors drop down over the valves.


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## Sick467 (Oct 29, 2019)

Thanks for the great explanation LG! I appreciate being straightened out. I will edit my above post to show this.


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## BuckHowie (Oct 1, 2021)

So I should get phenolic spacers


Lemans guy said:


> Gas fumes are heavier than air, they sink they do not rise. That is why your hot water heater in the garage sits on 2 cinder blocks. So the pilot light will not ignite a small gasoline spill.
> 
> The gas will fill every inch of space on the floor before it rises. Your intake is the same the gas vapors drop down over the valves.


I do all three carbs with phenolic spacers right!


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## Lemans guy (Oct 14, 2014)

Yes, because all 3 have gas in the bowls….any times that will fix it.


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## Lemans guy (Oct 14, 2014)

It is confusing as vapor lock is from a lean condition.

Vapor lock occurs on the suction side of the fuel pump. The pump creates a vacumn to pull the fuel and heat on the fuel line causes our modern fuels to vaporize quickly, called “vaporization rate” when it does that it stops pumping fuel because liquid pumps and vapor will not.

Now the car stalls, but because it is lean, not enough fuel, and will not restart for awhile. But if you sit there long enough it will cool down and then pump and start again.

Vapor lock creates a stall when running from a lean condition.

Heat soak occurs after shutdown from gas vaporizing in the bowls


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