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All you guys that have tripower, this is my question:
on cold start, my main carb (center carb) over flows the fuel bowel. It just pours out of the top overflow port. Is this just a float adjustment? If so can you direct me to some sight on how to adjust. Thx
It most likely is a high float setting but other causes could be a bad/leaky needle and seat or fuel pressure too high. To check, start and run the car a minute, shut off the engine and loosen the screw on the side of the float bowl. Put a paper towel under it and remove the screw. If fuel runs out the level is set to high. To lower it, put a wrench on the nut on top and while holding it from moving with one hand, use a large blade screwdriver to loosen the screw on top a little. Gas may seep out. Turn the hex bolt clockwise to lower the float level. The float should be adjusted to where you can see fuel at the bottom of the side opening but it’s not running out. It will probably take several back and forth to get it right. Always replace the screw in the side and hold the hex nut and snug down the top screw on top before restarting the engine. Considering the fuel is spilling out the top, if it’s too high in the bowl, I would turn the hex nut one half turn clockwise and see if that starts to help - but you may have to go further than that to get it down. If the fuel level doesn’t seem to be too high with the engine shut off, I would next get a replacement needle and seat and replace it as Holley has had some issues with leaking ones that flood the fuel bowl.
Dan gave you good advice. If I may add a little more to it:
All sorts of U-tubes here: https://www.holley.com/support/carburetor/ They will help you on the adjustments.
If you cannot adjust the float and get the proper setting or it does not remain set, you may have a bad float or needle. It is not uncommon to have a brass float with a pin hole or a plastic float that has absorbed fuel. Todays ethanol is not compatible with old carburetors.
Here is a good column on leaky Holley needle and seats which is attributed to the integral o-ring. Even in my limited little world I have run into this on friends and acquaintances cars several times in the last year. One member here on the forum went through 3 Holley needle and seats before the last one finally sealed.
This is apparently not a rare problem as of late and anyone with a Holley carb should be aware of it.
The 1/2 turn on the hex nut clockwise seems to have fixed the float problem. I took a look in the fuel level inspection hole and no fuel ran out, but I know starting it would have pushed fuel out. So I did it on a cold engine even before I started it, knowing it spews fuel out of the relief valve on top every time. I then fire it up and no fuel overflow. I might even sneak the hex nut back a 1/4 turn and see if the fuel bowl handles it.
I would highly recommend you check it often for the next few days. A brass float with a pin hole will very slowly take on fuel internally and sink, thus it won't shut the fuel off and you will be flooding again. Just a recommendation, I had one I thought was fixed, and went out the next morning to drive to work and the fuel had filled the bowl and out on the intake. It caught fire and cost me a hood. I was lucky it was only the hood.
The 1/2 turn on the hex nut clockwise seems to have fixed the float problem. I took a look in the fuel level inspection hole and no fuel ran out, but I know starting it would have pushed fuel out. So I did it on a cold engine even before I started it, knowing it spews fuel out of the relief valve on top every time. I then fire it up and no fuel overflow. I might even sneak the hex nut back a 1/4 turn and see if the fuel bowl handles it.
It’s possible 1/2 turn was too much. With it coming out the vent I figured it needed a drastic adjustment but I could have miscalculated. You can use a strong penlight to look in the sight hole and if the level seems to be well down from the bottom, then raising it back up a little is a good idea as too low can lean it out a little or possibly starve the engine if you apply the brakes real hard. Hopefully that will take care of it and you won’t have a bad float like R66 warned about.
there many ways you can do this, you can
just remove the check valve check if there any dirt in needle and seat re install make sure you lub the o'ring set the float and see what happens, or you can remove the carb. open the front bowl see what dirt you have you may want to rebuild the center carb. while your that far in your still going need a gasket kit to put back together , hope your not use and white teflon tape that would do it , what kind of fuel filters are in the Carbs.
I was just reminded of the 1st repair procedure for a Holley that may have fixed your problem. Next time, rap the top of the bowl with a plastic handle of a screwdriver or a rubber hammer to free a stuck float / needle.
Ya know, back in 67. I had a GTO with tri power and I had the same problem that wrapping the fuel bowl with a plastic screwdriver handle fixed it.
Ron: as you can see in the picture, mine has that valve on top. Is it better to change it to the correct fuel bowl? I’m not sure why it it was put on, maybe by mistake.
The rubber cap on top of the float bowl is not a overflow valve, it's a vapor vent that allows hot fuel vapor to escape to atmosphere vs escaping through the primary vent that's attached to the main body inside the air cleaner. It's supposed to avoid a over rich condition with very hot fuel, I think it's best to wire the heat riser valve open which keeps a good amount of heat off the carburetor.
I see, I’m still trying to determine what the difference is between my center carb and what’s supposed to be there. I’m told the vapor valve is not supposed to be on my center carb in 1967. Maybe previous owner had someone put the wrong float bowl on
Ya know, back in 67. I had a GTO with tri power and I had the same problem that wrapping the fuel bowl with a plastic screwdriver handle fixed it.
Ron: as you can see in the picture, mine has that valve on top. Is it better to change it to the correct fuel bowl? I’m not sure why it it was put on, maybe by mistake.
Are you going for NCRS Top Flight or other class? If not, the only concern I would have is the fuel leaking out, as you have already experienced, and the possibility of a fire. R66 has a 3367 with the vent valve. I tapped the hole for a sight plug and installed it to prevent the fuel leakage problem. GM only added the vent on one or two years per my knowledge. It was used on some Chrysler products with Holleys. GM deleted it, however I don't know for sure why. No other Holley carburetors still utilize the vent to the best of my knowledge. Keep in mind that if you plug the vent, the fuel is going in the throttle bore and air cleaner if your float sticks and the needle is open. Much safer in my opinion than all over the intake..
It's your call. Some of the NCRS experts will have to tell you what is suppose to be there, I am not that smart.
08-31-2023, 10:10 PM
Tri power question
