Quick Fuel / Holley leakage around needle

[Trucksareforwork]

I’m trying to figure out where I went wrong in life, and figure one of you Holley experts can help.

I rebuilt a 600 CFM vac secondary carb from quick fuel. Holley style. New everything including extensive soak in cleaner.

The secondary fuel bowl fills and ultimately shoots out of the vent. Very bad.

I have ensured the needle engages, and have bent the float a bit to ensure it’s going to close the needle. Even took the snap ring out of the bowl view hole and ensured the float was moving with fuel.

I have a fuel pressure gauge and it’s regulated to about 4psi. So that ain’t it.

I have set and reset the needle assembly, replacing the o ring twice. Still overfilling and flooding dangerously.

Before I go further, is it possible that the needle and seat channel is corroded to the point that the o ring won’t seal? That’s all I can figure at this point. It’s not a “leak” it’s a gusher.

Any other advice? I ordered some viton rings thinking maybe I’m just rolling the rubber ones off when I’m installing.

I’m not a Holley expert, but have rebuilt a few carbs and this is perplexing.

 

[nvrenuf]

Could the gasket under the secondary metering plate be wrong?

 

[bucket]

How "old" was the new needle and seat? New ones that have been sitting out for a year or more can cause issues sometimes.

When you originally assembled the carb, did you give the fuel inlets a blow test with the carb right side up and also upside down?

Did you change the floats?

 

[nvrenuf]

How "old" was the new needle and seat? New ones that have been sitting out for a year or more can cause issues sometimes.

When you originally assembled the carb, did you give the fuel inlets a blow test with the carb right side up and also upside down?

Did you change the floats?

Great points to check!

The needle/seats are interchangeable, aren’t they? If so, swapping front to rear would verify if that’s the problem (extra work to reset the float heights though).

 

[Trucksareforwork]

Could the gasket under the secondary metering plate be wrong?

It very well could be because I tend to have to do everything twice and I only did that once. Is this a possible failure mode for this kind of carb? I figured the bowl could only fill from the needle side. How would the wrong gasket or gasket orientation cause the bowl to overfill?

 

[Trucksareforwork]

How "old" was the new needle and seat? New ones that have been sitting out for a year or more can cause issues sometimes.

When you originally assembled the carb, did you give the fuel inlets a blow test with the carb right side up and also upside down?

Did you change the floats?

Needles were new in box with a Holley carb kit. I did give the inlets a blow test, but did NOT change the floats. The float appears to be floating fine when engine is off and I put a screwdriver on it to actuate it throught the fuel window hole in the bowl.

 

[Trucksareforwork]

Great points to check!

The needle/seats are interchangeable, aren’t they? If so, swapping front to rear would verify if that’s the problem (extra work to reset the float heights though).

I had not done that, and don't think my hardline fuel line will let me do it (primary bowl outputs to passenger side, and would be on driver side if I spun it to the secondary side).

 

[bucket]

Needles were new in box with a Holley carb kit. I did give the inlets a blow test, but did NOT change the floats. The float appears to be floating fine when engine is off and I put a screwdriver on it to actuate it throught the fuel window hole in the bowl.

If you can raise the float up to close the needle/seat and the fuel still flows, you have an issue. Are you saying this issue was not present when you did the initial blow test?

 

[bucket]

This is a dual feed carb, right?

 

[bucket]

Also, you can blow test the bowl assembly, while it's removed from the carb. If it passes then, but not when installed, the float may be hanging up.

 

[nvrenuf]

I had not done that, and don't think my hardline fuel line will let me do it (primary bowl outputs to passenger side, and would be on driver side if I spun it to the secondary side).

Not the whole bowl assembly, just swap the needle/seat.

 

[nvrenuf]

It very well could be because I tend to have to do everything twice and I only did that once. Is this a possible failure mode for this kind of carb? I figured the bowl could only fill from the needle side. How would the wrong gasket or gasket orientation cause the bowl to overfill?

I’m just wondering if there is a hole where it shouldn’t be allow fuel to push up the vent. I can’t remember if there are other passages to the vent to other than the breather thing at the top.

 

[Trucksareforwork]

I got in the shop and took a little stone bit on a dremel to the inside tunnel where the needle o ring rides. There was some fuel corrosion in there that I guess my rebuild soak either aggravated or simply didn’t dissolve.

After that I put a little oil on the o ring and in the tunnel, and voila, it sealed.

I wish I had thought of that over the weekend while I must have removed and replaced the bowl a dozen times or so.

After a couple runs and a few adjustments, the engine is back to normal and no longer loading up or shooting fuel all over.

Lesson learned. Thanks for the help.

 

[Trucksareforwork]

Not the whole bowl assembly, just swap the needle/seat.

Yeah, duh. You can see how my mind works. Don’t pick up the dipstick, lower the whole car.

 

[Craig Nedrow]

I love a happy ending, I also have a QF carb I will be running on the the 489 BB, hope it works as good as the hollies I am used to.