Looking for this part, Have one for sale?

[Lou]

Hello and Happy New Year to all.

I am hoping that someone can help me locate a fuel return line fitting for a Holley Carb for my mutt. The first photo shows the carb without the fuel return fitting.

The second photo shows the fuel return fitting I am looking for that screws in place of the plug in the first photo. That photo shows the fitting with the hose going back to the tank for the fuel return.

Thanks in advance for your assistance.

Holley without return fitting2.jpg

Holley with return fitting2.jpg

[rickf]

That is the same part as the straight 151 using the Zenith carb and also the A1. I seem to remember somebody had them aftermarket. And I think, this is going from long ago memory, that there is that fitting off the shelf in plumbing stores that does have the straight threads. That was talked about on here a long time ago. Finding that conversation could prove to be interesting.

[Horst]

Looks like the fitting of a Zenith A2 carb. (Holleys did not have a return line from the factory).

[Hambone]

Rick would know, but I think that fitting is different between the A1 and A2.

[rickf]

The A1 was a 90 degree fitting and the A2 was a 35 degree fitting. Due to the different positions of the incoming fuel lines.

[Hambone]

The A1 was a 90 degree fitting and the A2 was a 35 degree fitting. Due to the different positions of the incoming fuel lines.

I'm talking about the fitting that one screws in to, it has something to do with where the flow channel to the bowl is located.

[rickf]

Ok, Now I see what he is looking for. I am going to have to go into my box of Holley cores and see what I have but the top sections of Holley carbs are very hard to come by because of the "screw a pipe thread fitting into a straight thread hole" syndrome. Most of the Holley's gut the inlet fittings broken and there is no way to repair it and since the Holley was only made for a couple years there are no replacements. Back then people just threw them out. And Holley never did have a fuel return, and neither do any of the other carbs. The A2 has a VAPOR return in that position that will return a tiny bit of fuel if there is not vapor but it is NOT a fuel return. The Holley did have a vent line that went to the air cleaner from the bowl vent. So, That said, I really don't know what to look for in that fitting. I will look through my books and see if it is listed in the Holley carb breakdown.

[Lou]

Thank You all for your suggestions. Sadly, the Zenith return will not fit the Holley carb. Took the return fitting out of my old zenith and it will not fit the Holley. Holley on the left and zenith on the right in the photo. The zenith is a larger diameter and has the threads near the bottom.

Zenith and Holley Fuel Return.JPG

I am still looking for the return fitting for the Holley.

Rick, believe you hit on a good point, it is mainly a vapor return but still acts as a fuel return. Will provide an explanation on why I am looking for one. These carbs were not built for today’s fuels with high vapor pressure. If you don’t believe me take a 1 gallon fuel can, fill it halfway up and shake it up. The can will swell up to the point where you think the vent on the can is going blow off like a missile.

Have been having an issue because of this. When the mutt is hot and stopped for a while, even for a short while like getting gas, the mutt floods. Have to hold the gas pedal to the floor to restart because fuel dumped into the engine while it sat. If the mutt does not sit, it restarts fine. For example, Meg is learning to drive stick, so if she stalls it, starts right back up. Same if i stall it while driving in the woods. Has to sit for a while for the issue to occur.

At first blamed float level or leaking needle and seat, it is set fine. To rule out something I missed while rebuilding the carb, actually scored a Brand New NOS Holley and it does the same thing, so can rule out the carb.

Found out when the gas cap was opened air escaped so the tank was becoming over pressurized. So ran with the fording vent open for a while and it helped make the issue much better, but not go away completely. During the winter with doors and top on fumes from the gas cap vent into the mutt and make it uncomfortable so have to run with the gas cap vent closed.

So to resolve the over pressurization issue took apart the one way vent in the top of the tank and modified it so it can vent all the time either way. This is the vent line that runs back to the air cleaner. With this modification, even with the vent gas cap fording valve closed, the tank no longer builds up pressure.

Issue remains so did this.

Holley Carb T Return.jpg

Added a T in the fuel line, added a return to the right in the photo. Added some restriction in the form a copper washer with a small hole, similar to the size of the vent hole in the zenith photo above. Improved but still floods.

My theory is that vapor pressure is so high, that while sitting the pressure is pushing the needle valve off the seat and dumping excess fuel in the carb. As an experiment removed the air vent line that runs from the top of the carb (blue line in photo that use to run to air cleaner) and never see fuel dumping out of it before or during hot restarts.

Not sure how the excess fuel is getting into the engine but the fuel bowl is not overflowing because it would be exiting out of the vent line mentioned above.

So in an act of desperation to resolve this issue, looking for the Holley fuel return vent fitting. There had to be a reason it was added to the Holley carb and maybe this was it.

[Horst]

I don’t think this part is available of the shelf. Why not just taking the brass 90 degree part from the Zenith return and drilling and tapping the Holley cap accordingly?

On the other hand, don’t think it would make things differently compared to that T-connecting.
On the Holley and the Zenith A1 carb there is the fuel filter under it, in a Zenith A2 carb there is the return and as such the filter is external.

[Hambone]

Next time I'm at Red River, I will see if I can find that fitting for you.

[Lou]

I don’t think this part is available of the shelf. Why not just taking the brass 90 degree part from the Zenith return and drilling and tapping the Holley cap accordingly?

On the other hand, don’t think it would make things differently compared to that T-connecting.
On the Holley and the Zenith A1 carb there is the fuel filter under it, in a Zenith A2 carb there is the return and as such the filter is external.

Yea, I have been thinking about doing that. If I cannot locate the original part will do exactly that. There may be a difference if the cap that has the vent is up higher. Noticed that on the photo of the holley with the vent, the vent line runs straight down to the fire wall, then the metal line runs straight down to the tank. Maybe my vent is not working properly because my line dips down trapping fuel, then runs up along the fender then goes up the firewall.

Have you ever tried to blow air through a hose that has water or fuel in it that has a dip? it is amazing how much restriction the liquid can cause. Maybe instead of the vent pushing excess pressure back to the tank through my pseudo vent, it is pushing the needle valve open instead.

[Lou]

Next time I'm at Red River, I will see if I can find that fitting for you.

That would be awesome, Thank You!

[m3a1]

Just out of curiosity...is your fuel cap one of the caps which has a vent that can be opened and closed?

[rickf]

All of the caps prior to the emissions setups are vented caps. And they need to be in the open position all the time for normal driving. The only time they are closed is during fording. If you have yours closed all the time then you are getting supply air into the tank from somewhere or it would die from lack of fuel to the carb.

[Lou]

Gentlemen, thanks for your questions concerning the fuel cap vent. The rather long post above explains how the tank is vented to relieve pressure and to let air in the tank. The modified vent works fine, the mutt has no issues from lack of fuel, can drive 55 all day long. Please read my rather long post, it explains what I have done to try and resolve the issue.