float bowl overflow

[Richard McDonel]

The puzzlements never end.  

With new ZTherapy  needle valves in place, and having set the float-bowl levels at 23 mm on a bench-test, glass jar I rigged up, I found my carbs suddenly worked far better than when I used the plastic-tube-attached-to- the- bottom-of-the-bowl system.  Car ran nicely.   But for whatever reason, the front carb is now  blowing fuel out its vent tube.  Remove the float lid, and everything looks fine; the float pivots as it should, and the new needle valve moves smoothly.  But I`m still puking gasoline.    

Any thoughts would be appreciated.

 

 

[Mark Maras]

 A possibility is the ramp angle of the float tang. I'm going to let @siteunseen describe the problem and the fix.

[siteunseen]

I'm stumped on all of the sudden overflowing but here is what Mark is referring to I believe.

When it's assembled and overflowing I would suggest sticking a red straw from a can of WD-40 down the overflow bung to make sure the float isn't stuck somehow once the lids are on.

 

[Fred Sigarto]

Same thing happened on my Z years ago, had to remove the float, it had fuel in it. Replaced with another float, ran fine.

 

[Stanley]

Floats need to sit correctly in the float bowls, otherwise they can stick against the sides of the bowls. Adjusting (bending) the hinge tab and/or a light touch with sandpaper on the float will fix that. If the valve isn't new it could have some gunk in it - fix with carb cleaner. The other answers are also correct.

[jonathanrussell]

What I have found is....if you compare the needle jets that were originally installed in these cars 47+ years ago with the new needle jets that come in the carb rebuild kits, you will notice that they are different. New needle jets have a pretty thin needle that contacts the tab on the float. The old had a much thicker needle that contacted the tab. What I have observed is that if the tab is too curved the thinner new needle jet needle gets hung on the tab. So, I try really hard to bend the tab so that it allows for the right fuel level but also is as flat as possible. 

[Mark Maras]

1 hour ago, siteunseen said:

I'm stumped on all of the sudden overflowing but here is what Mark is referring to I believe.

When it's assembled and overflowing I would suggest sticking a red straw from a can of WD-40 down the overflow bung to make sure the float isn't stuck somehow once the lids are on.

 

 Thanks Cliff. That's the thread that discusses the float tang and the newer style needles and seats.

[siteunseen]

1 hour ago, jonathanrussell said:

What I have found is....if you compare the needle jets that were originally installed in these cars 47+ years ago with the new needle jets that come in the carb rebuild kits, you will notice that they are different. New needle jets have a pretty thin needle that contacts the tab on the float. The old had a much thicker needle that contacted the tab. What I have observed is that if the tab is too curved the thinner new needle jet needle gets hung on the tab. So, I try really hard to bend the tab so that it allows for the right fuel level but also is as flat as possible. 

I agree 100%.

I would love to have Grose valves. I bet someone could get the patent and start remaking them. Seems like they were in Massachusetts maybe?  Anyway...

@Captain Obvious  I'd buy four. 

Edited July 26, 2019 by siteunseen

[Captain Obvious]

Send me a print and we'll talk.   

[Richard McDonel]

Thanks everyone,

I had checked the float for leaks, but all seems dry.  I did not use the push-down with a straw method suggested, and there might be something there.  Right now, the float and lid assembly are sitting on my desk, and while the side-to-side variance is not great, there is no question the float isn't hanging dead centre.  Enough to cause friction with the wall of the bowl?  We'll find out tomorrow morning  when I'll be brave and try to bend things just a tiny bit to get it all centered.  

What is the significance of "grose jets?"
 

 

 

[jonathanrussell]

It was a needle and seat / jet alternative that was available for our Hitachi SU carbs at one time. I don't know when they stopped being available. They are still available for other SU carbs. I have never used them so I don't know first hand how well they work but just based on the photos and concept I would think they would be an improvement. The photo below is a grose-jet for a Triumph but it shows the concept.

[siteunseen]

From the www

One day I decided to drive up to Stoneham, near Boston, and pick up a Grose Jet.  This was in the days before Mapquest or GPS so I looked up the address in the ad and found a map of the town.  It was called D & G Valve Mfg. Co., Inc. on 8 Mt. Vernon Street, and I really did not know what to expect.  Would it be a large brick factory with chain link fence and guard house?

It turned out to be a house in an old Stoneham neighborhood.  I went to the door and knocked.  A large man with a machinist apron on greeted me and invited me in to the manufacturing shop set up in the basement of his house.  He wanted to know what model of carburetor I needed a gross jet for.  Since I was there I picked up one for the Quadrajet on my mother’s Pontiac as well as the Holley on my VW.  He took the time to show me how his jigs were set up to manufacture the different Grose Jets.  For motorcycles he used glass for the larger ball to keep the mass down and deal with the vibration better.

He pulled two Grose Jets out of the drawers of his cabinets and sold me what I was looking for. 

I drove home enlightened to see what a Yankee inventor could produce out of the basement of his house and become famous for in an underground sort of way.

Look up D & G Valve on the Internet, you can still find it.  Amazing.