# 66 GTO TRI-POWER FUEL BOIL OVER



## truegoat (Nov 30, 2019)

So got out the goat for the first time , get back to garage and fuel leaks all three carbs after shut off, Ok I know whats going on here so, how does this plan look for you guys that also had this,, So after I install the Heat Insulator Gaskets I am thinking about the MR GASKET fuel regulator and set it at about 3. Also was thinking maybe about a return line to the tank what do you think? two pics of my set up below


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## PontiacJim (Dec 29, 2012)

The phenolic spacers will help. The 1/4" return line to the tank should help - I would go with the period correct filter having the 3 fittings versus the later fuel pump with the return line. My thinking is that higher up/close to the carbs will allow some of the built up pressure from the hot gas/boil over to be routed out the return line like a pressure relief valve.

I would hold off on the regulator and do the first 2 above. At 3 pounds, and the 1/4" return line, you may not have enough fuel to fill all 3 carbs when wide open for a good blast down the road - it may lean out on you.

Have you checked carb float levels? Possibly too high. Also, some needle & seat assemblies are better than others and they may not be sealing well, or they are deteriorated.

You can also block the intake exhaust crossover that goes under the carb which will keep additional heat off the carbs. Good for summer, but can be balky in cold weather starts and running until the engine warms up.

Get the engine to run cooler. Fan shroud? It doesn't look like you have one. Colder T-stat, minimum 180, but I like 160 degree. Radiator new/flushed? Remove hood insulation if you have it as it traps heat. From the photo/angle, it looks like one of your fan belts is out of alignment. Make sure no slipping of the belts at the water pump. Can you grab the fan and turn the engine with it or does the fan pulley slip on the belts? Timing - initial & total? Using the vacuum advance on the distributor - how much advance does it give, it can be too much? Engine could be running lean which makes it run hot. Do you know what the jet size is on the carbs? How do the spark plugs look?

Do the initial items first, but it can be other things making the engine run hot and adding to the situation.


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## truegoat (Nov 30, 2019)

truegoat said:


> So got out the goat for the first time , get back to garage and fuel leaks all three carbs after shut off, Ok I know whats going on here so, how does this plan look for you guys that also had this,, So after I install the Heat Insulator Gaskets I am thinking about the MR GASKET fuel regulator and set it at about 3. Also was thinking maybe about a return line to the tank what do you think? two pics of my set up below
> View attachment 133966
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> View attachment 133967
> View attachment 133967


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## truegoat (Nov 30, 2019)

my 66 does not have a setup for return line, would need to change the sender in the tank as well as the stock fuel pump,


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## PontiacJim (Dec 29, 2012)

truegoat said:


> my 66 does not have a setup for return line, would need to change the sender in the tank as well as the stock fuel pump,


Why do you have to change the fuel pump? Did you miss this,"I would go with the period correct filter having the 3 fittings versus the later fuel pump with the return line." ?


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## truegoat (Nov 30, 2019)

got a pic of it, and ya I have problems with understanding some things after my stroke


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## PontiacJim (Dec 29, 2012)

truegoat said:


> got a pic of it, and ya I have problems with understanding some things after my stroke


OK, I'll let you slide this time. LOL My boss had a stroke, but caught it early. He was out of work for a few days in recovery, but in my opinion, the stroke did some damage even though he is 98% ok.

If you look online, you will see that you can get a reproduction AC brand (the canister is blue in color) fuel filter having the needed 3 ports, and you can purchase the reproduction bracket that holds the filter. Look here: 1964 -66 Pontiac GTO Tri-Power with AC 1967 Pontiac GTO Ram Air Rochester AC GF-98 Fuel Filter
, and you can purchase the reproduction bracket that holds the filter. Inline Tube shows 3 different gas filter brackets. Here is the one listed for 1966. Look here: 1966 Pontiac GTO Tri-Power Fuel Filter Bracket

You will then need to purchase the 1/4" return line back to the tank, and a new fuel tank sending unit having the 1/4" return line fitting.

The reason I suggested this is that it will look original and the return line is closer to the carburetors. The later fuel pumps having the return line sets lower and returns the fuel further away from the carb, so my thinking is that it will only work with the engine running while the AC fuel filter will pass any pressure developed from the boil over back to the gas tank and not build up in the carburetor bowls.

I would suggest getting rid of the fuel block which is picking up heat off the engine and not helping, and the individual fuel lines. Go back to a factory setup which will also keep the fuel lines away from the engine. Look here: 1966 Fuel Lines and Fittings

Several members have used Pontiac Tripower for help, rebuilds, and parts. If you contact them and tell that what you are wanting to do, they can most likely provide you with everything you will need.


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## 64Indian (Mar 31, 2020)

I have two Triowers and I put Mr Gasket regulators on both of them and spacers and that solved all my issues with ethanol gas. I set them at 3lbs and have had no further issues. Many fuel pumps run 5lbs or more and thats too much on these carbs.. I experienced heating and hot start problems until I added the above.


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## truegoat (Nov 30, 2019)

PontiacJim said:


> OK, I'll let you slide this time. LOL My boss had a stroke, but caught it early. He was out of work for a few days in recovery, but in my opinion, the stroke did some damage even though he is 98% ok.
> 
> If you look online, you will see that you can get a reproduction AC brand (the canister is blue in color) fuel filter having the needed 3 ports, and you can purchase the reproduction bracket that holds the filter. Look here: 1964 -66 Pontiac GTO Tri-Power with AC 1967 Pontiac GTO Ram Air Rochester AC GF-98 Fuel Filter
> , and you can purchase the reproduction bracket that holds the filter. Inline Tube shows 3 different gas filter brackets. Here is the one listed for 1966. Look here: 1966 Pontiac GTO Tri-Power Fuel Filter Bracket
> ...


Need a drawing showing system your talking about, sorry not understanding placement of everything, and where would I get a correct sender for tank when the 66 did not have a return line


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## PontiacJim (Dec 29, 2012)

Go back and re-read my earlier post. Everything that is highlighted in *red *is a link to the information you need. So click on the red links and you will see the items I am talking about.

Do you have a 1966 Service Manual? It should have diagrams for the tri-power.


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## truegoat (Nov 30, 2019)

no manual , I see the stuff im going to get ,its the placement and locations I need a drawing for


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## PontiacJim (Dec 29, 2012)

truegoat said:


> no manual , I see the stuff im going to get ,its the placement and locations I need a drawing for


I don't have any good drawings or photos of the 1966. The restoration guide shows the '66 set-up which has the fuel filter bracket attached to the front carb like the one from InlineTube. The fuel inlet at the front carb looks a little different between 1965 and 1966. There are photos on the internet that you could use for reference, but this link is a detailed look at the tri-power with photos: Engine Detailing - Tech Articles - High Performance Pontiac Magazine - Hot Rod

Get a shop manual on CD as this should also have what you need: 1966 Pontiac Tempest / GTO Chassis Shop Manual | OEM


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## truegoat (Nov 30, 2019)

Ok this is what I got the large canister filter with 1/4 return on it , 1/4 line goes back to the tank with a new gauge with two outlets one is 1/4 inch, now in drawing you see that the gauge is in the middle backside of tank, so is it ok to return there or does the return need to come in the top of the tank?


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## PontiacJim (Dec 29, 2012)

Not sure what you are asking. The 1/4" return line will attach to the 1/4" outlet on the sending unit which is right next to the gas line coming out that connects to the fuel pump. Both outlets should be on the top of the tank.

Your vent is correct and it remains a vent. You should not have any other outlets on the gas tank.

Make sure you use a good quality rubber hose to join the steel lines at the tank and fuel pump. I prefer to use the high pressure rubber hose used for fuel injection cars. You may have to ask for it instead of the typical gas line that the parts store will give you. I believe it is rated at 200 or 250PSI and this is stenciled on the outside of the hose. Your local parts store should know what it is.


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## truegoat (Nov 30, 2019)

what im asking is if the return line is ok ,the guage with the return line is not on top of the tank its in the middle


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## PontiacJim (Dec 29, 2012)

Should be fine. Looking at tanks, it appears 1968 and up were on the top.


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## truegoat (Nov 30, 2019)

PontiacJim said:


> Should be fine. Looking at tanks, it appears 1968 and up were on the top.


thanks for all your help should solve all my problems, just gota keepreturn line high as posible


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## Old Man Taylor (May 9, 2011)

truegoat said:


> So got out the goat for the first time , get back to garage and fuel leaks all three carbs after shut off, Ok I know whats going on here so, how does this plan look for you guys that also had this,, So after I install the Heat Insulator Gaskets I am thinking about the MR GASKET fuel regulator and set it at about 3. Also was thinking maybe about a return line to the tank what do you think? two pics of my set up below


It has been my experience (56 years) that Pontiac had the float levels set too high on the tri-powers. They had a tendency to flood, especially the rear. Try lowering your floats 1/32-1/16". In case you're not familiar with the procedure, that means you make the dimension larger with the air horn upside down. It's a much simpler trial compared to some of the other things you are considering. As general information I do this on my '64 GTO that has nitrous and runs in the 10's. It's never starved for fuel, and they never overflow. If it does starve for fuel, then you need to upgrade your fuel system.


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## truegoat (Nov 30, 2019)

Old Man Taylor said:


> It has been my experience (56 years) that Pontiac had the float levels set too high on the tri-powers. They had a tendency to flood, especially the rear. Try lowering your floats 1/32-1/16". In case you're not familiar with the procedure, that means you make the dimension larger with the air horn upside down. It's a much simpler trial compared to some of the other things you are considering. As general information I do this on my '64 GTO that has nitrous and runs in the 10's. It's never starved for fuel, and they never overflow. If it does starve for fuel, then you need to upgrade your fuel system.


 well already done what I was going to , as soon as it stops snowing I will take it out and see what happens, I will do what you say if I still have a problem, thanks


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