MTFCA Forum

I'm having issues with my 1926 roadster with a Kingston L4 iron carburetor. Since I've owned the car for a couple years, I've had issues starting the engine after is sets for any period of time with the filter petcock shut off, as in it takes some more cranking and fiddling with the spark and throttle. If I leave the petcock on with the engine off, fuel will slowly drip out of the bottom of the carb through the vent. Once the engine is running, the fuel does not drip out of the vent or at least not noticeably. Two weeks ago, I couldn't get the engine to fire after it had sat for a couple months even though I put fresh gas in. I removed the carb, disassembled it, cleaned everything in a sonic solvent bath, and reassembled. The steel float needle and brass seat looked fine, and I set the float level to 11/32" exactly. The copper float is good. The spray needle had no sign of wear on the tip, and it is straight when holding a machinist's straight edge to it.

After installing the carburetor with the spray needle set at 1 turn out, the engine fired right up quicker than it ever has. After the engine reached running temp and while driving down the street, I set the spray needle to the ideal position, which ended up being 3/4 turn out. I parked the car in the garage and found about 30 minutes later that fuel is still dripping from the bottom out of the vent when the petcock is left open. I closed the petcock and didn't start the engine for the last week. From the fuel dripping from the vent, I assume I have a needle and/or seat issue.

When I tried to start the engine today, it would only crank with a very rare sputter. After trying to start it for some time on and off including fattening the spray needle to between 1 and 1.5 turns out and also playing with the carb choke since the garage was 43F, fuel began running out of the hot-air side of the carburetor and out of the bottom vent. I pulled the plugs, and they are bone dry. I confirmed spark at the plugs.

While I am capable of rebuilding the carburetor, my time constraints right now coupled with the cost of rebuild parts lead me to be fine with purchasing a rebuilt one. Before purchasing one, I'd appreciate input on if it seems that the carburetor is in fact the issue. To me, it certainly seems to be the constant variable giving me trouble. Also, is going with a rebuilt unit the way to go, or should I spend the money on a new needle/seat set, air valve shaft, air valve top screw, spray needle assembly (mine is a later u-joint style). These parts come out to about $95 after shipping and tax from Lang's, which is why I'm fine giving Lang's another $60 for a rebuilt unit plus shipping cost back to them with my core.

Also, does anyone have a recommendation where I can purchase a rebuilt carburetor or rebuild parts? Lang's is the only place I've found, but I haven't called to see if they have a rebuilt L4 in stock or if I'll need to send mine in for rebuilding.

Thanks for the help!

Contact Corey Walker on this site - he does a good job !

I have always found the Holley NH a dependable carburetor with easy to acquire parts. If you want your Kingston rebuilt or buy another carburetor Russ Potter is a great and dependable source.
Twooneseven sevenfivenine sevenfiveninetwo

Fuel leaking does sound like it could be the carb itself.
I’ve included the photo below to illustrate a couple things. The painted body shows the fuel vent hole next to the brass model plate. If fuel is coming out of that vent hole then gas is not being shut off by the float or needle valve that the float closes. From your original post, it appears you do not have a Gross Jet style valve, shown in the middle of the photo. The gross jet has a reputation of sticking open, causing fuel to overflow.
Another reason for over flow is if your float adjustment is not quite right. I find it takes me a couple tries to get it right. On one occasion I found a glob of Permatex on the float which kept it from rising.
If the fuel is not leaking out of the vent, but still dripping, you might have a leaky gasket or seal around the bowl.
Another area that might leak is shown in the photo of the unpainted body. There is a hairline crack on the inlet that the fuel line connects to. This can happen if the brass elbow is overly tightened. It’s recommended to use sealant rather than over tighten to get it to line up.
Hope this helps.
I do agree that getting a rebuilt carb from a quality rebuilder is a great option.

No matter how good it looks, the old float valve is worn, and that is the source of your too-full bowl, dripping/overflow, and hard starting.

A common "fix" is to run the needle in a drill and hold sandpaper against it. Some folks claim that works...to some extent...but what remains is a needle which is no longer round nor straight, and the seat will still have a wide (too wide) and worn chamfer that the needle is trying to seat into. Both parts can be reworked, but requires equipment beyond that which the average owner will have.

Just a thought but is your fuel cap venting properly?

The valve on the fuel filter might be allowing some fuel to get by when the valve is closed. However, this would not cause the dripping from the carburetor if the float and valve are in good condition. First thing be sure the float actually floats. Sometimes a pinhole leak can let the fuel fill the float and then the float will not rise. Next replace the fuel intake valve and gasket. I like the viton tip needle if one is available. tighten the seat but do not make it too tight or you could crack the carburetor body. Check the float level. Bend the tab a bit if necessary. Be sure the tab is flat where it contacts the needle valve so it won't stick but push the needle straight up. I set it where it is level when closed. Hold the carburetor upside down and bend the tab to set the float level.
Norm

KBurket wrote: ↑

Wed Feb 02, 2022 1:30 am

Fuel leaking does sound like it could be the carb itself. . . .

Thanks for the details and photos. Correct, the carb doesn't have a Gross Jet valve. Here's the interesting thing, which might just be my ignorance of how the L4 works, but the fuel is not coming from the hole above the bowl adjacent the air-valve shaft. It's coming out of the hole in the body where the bowl nut fastens. I've confirmed that the fuel is not seeping out from the nut threads but is actually coming out of the pictured hole even to where it makes air bubbles. It only comes out of this area when the fuel petcock is turned on and the engine is off and when I try to start the engine but can't. Your thoughts?

Scott_Conger wrote: ↑

Wed Feb 02, 2022 10:10 am

A common "fix" is to run the needle in a drill and hold sandpaper against it. Some folks claim that works...to some extent...but what remains is a needle which is no longer round nor straight, and the seat will still have a wide (too wide) and worn chamfer that the needle is trying to seat into.

Agreed. I'd never mess with trying to refurbish a needle and seat to save $10. With my response to KBurket, I'm not sure the needle/seat are the issue if the fuel is coming out of the hole in the body down at the bowl nut.

That hole is in fact the overflow tube for the bowl, when the fuel level is not being shut off fully by the float valve, or the float level is terribly maladjusted.

Odds are strong that your float valve is failing (very common) or your float is leaky and is not buoyant enough (not as common as people would have you believe)

FYI, courtesy originally of Dan Treace on 7/21/13:

Contact Corey Walker on this site - he does a good job !

Both Russ Potter and Corey Walker do great work, but have to shout out to Corey for recently fixing my leaking Holley NH. This carb was a new rebuild and I had just installed one of Scott's Full Flow float needle seats and valve, and set the float to factory clearance, but after a week of great running the carb starting leaking.

Perplexed on the cause, sent that carb off to Corey in Brownsville, TX to have him check it out. Corey always test runs any carb he does on his T, so you get a run tested carb from him always. Seems that the carb I had was a fresh rebuilt from another, and the float seemed good to me. But over course of several days, Corey found that shiny float had a tiny tiny pin hole, that let gas soak slowly into the float. He replaced the float and now the carb is leak free and running great.

Corey Walker email : wlkma9ATgmail.com

Not that it makes any difference but Corey lives in Brownsboro, Texas which is 460 miles from Brownsville, Texas…

DanTreace wrote: ↑

Wed Feb 02, 2022 2:56 pm

Contact Corey Walker on this site - he does a good job !

Both Russ Potter and Corey Walker do great work, but have to shout out to Corey for recently fixing my leaking Holley NH. This carb was a new rebuild and I had just installed one of Scott's Full Flow float needle seats and valve, and set the float to factory clearance, but after a week of great running the carb starting leaking.

Perplexed on the cause, sent that carb off to Corey in Brownsville, TX to have him check it out. Corey always test runs any carb he does on his T, so you get a run tested carb from him always. Seems that the carb I had was a fresh rebuilt from another, and the float seemed good to me. But over course of several days, Corey found that shiny float had a tiny tiny pin hole, that let gas soak slowly into the float. He replaced the float and now the carb is leak free and running great.

Corey Walker email : wlkma9ATgmail.com

New rebuild? The "rebuilder" missed a critical float test that would have found the smallest pin holes.
Every carb I restore gets the boiling water test. That includes the few new floats I have installed. There is rebuilds & there is rebuilds.
OP seems to need a new needle & seat. Very easy fix. Go viaton.

Scott_Conger wrote: ↑

Wed Feb 02, 2022 1:00 pm

That hole is in fact the overflow tube for the bowl, when the fuel level is not being shut off fully by the float valve, or the float level is terribly maladjusted.

Odds are strong that your float valve is failing (very common) or your float is leaky and is not buoyant enough (not as common as people would have you believe)

Thanks. I assumed the hole functioned as both overflow and vent, so it's interesting they have a separate vent. When going through the carb, I submerged the float in gas for a few days to confirm it is solid with no leak, so my money is on the needle/seat.

Interestingly, I tried to start the engine today and was successful only after turning the spray needle from 3/4 turns out to 2.5 out. The engine fired with a bad miss and ran that way for about two minutes. Once the engine had some heat in it, I advanced the throttle way up, and all cylinders came alive. After setting the throttle/spark to idle and adjusting the spray needle to 3/4 turn out, the engine ran just fine. Anything less that 1/2 turn out or more than 1 turn out would try and kill the engine. After shutting down and keeping the fuel petcock open, I have yet to see any fuel coming out of the overflow for the last couple hours. I'm wondering if there wasn't debris on the needle/seat that by opening the spray needle wide passed enough fuel to flush it? I'm going to try and start the engine later after it is fully cold again to see what happens and can report back.

Soaking the float in gas is not the best test. Brass float. Submerge it in a pot of very hot water. Just off boiling. If there are holes, you will see bubbles.
For such off running issues. Fisrt thing. Drain the bowl into a clear glass container. Note the dirt flakes. Refill & drain again. The offending dirt will usually come out of the jett. Chase the dirt source. Sediment bowl screen in tact?
Dripping when parked is a needle/seat issue. Could be a bit of dirt, but as described a viaton needle should solve that problem.

you may have had crud that finally passed like a kidney stone through the main jet after opening up the needle. But know that this is an entirely different and unrelated issue from the carb overfilling. That said, if there is crud in the bowl that is coming from the tank, it may well foul the float valve and cause it to leak (but unscrewing the needle valve is an entirely different part in an entirely different area of the carb).

speedytinc wrote: ↑

Wed Feb 02, 2022 3:59 pm

Soaking the float in gas is not the best test. Brass float. Submerge it in a pot of very hot water. Just off boiling. If there are holes, you will see bubbles.
For such off running issues. Fisrt thing. Drain the bowl into a clear glass container. Note the dirt flakes. Refill & drain again. The offending dirt will usually come out of the jett. Chase the dirt source. Sediment bowl screen in tact?
Dripping when parked is a needle/seat issue. Could be a bit of dirt, but as described a viaton needle should solve that problem.

Thanks for the alternate method. Weighing down a float in gas for a few days in a sonic tank with a couple 5-minute sonic-cycles hasn't let me down yet and also cleans the float, and I've caught many a faulty float, although the physics of the hot-water method makes sense. The float wasn't full of fuel when I disassembled it, so I knew it wasn't sinking. No sediment in the carb bowl or fuel when I drained it the other day. I cleaned the tank and sediment bowl assembly last year and also installed a Wix in-line filter downstream the sediment bowl as a fail-safe.

Scott_Conger wrote: ↑

Wed Feb 02, 2022 4:18 pm

you may have had crud that finally passed like a kidney stone through the main jet after opening up the needle. But know that this is an entirely different and unrelated issue from the carb overfilling. That said, if there is crud in the bowl that is coming from the tank, it may well foul the float valve and cause it to leak (but unscrewing the needle valve is an entirely different part in an entirely different area of the carb).

I'll report back what happens when I try to start it either this evening or tomorrow. Is it common to have to fatten the mixture to 2.5 turns out to start in 43F weather?

To your question: No, it is not...

As it is, L-4 carbs have a tendency to run rich and get marginally fair mileage at the very best.

I have my L4 set at 3/4 turn and leave it there. On the rare occasion it gets below freezing, I sometimes run richer at 1 full turn max for a short time until it warms up. And yes, it runs rich as indicated by my sooty plugs. Of course I’ve never driven my Rpu higher than 350 ft above sea level …

If your float valve is leaking you can get a viton tipped one. Bob’s has them on eBay now. If your float valve is leaking enough that gasoline is coming out the overflow then I’m not sure that making the mixture richer to facilitate starting is the answer. That would indicate another problem since it would already have too much gasoline. When I get one flooded I screw the needle in to shut off the fuel then open the throttle and crank it. I believe the Kingston also should have a taller float like the NH did in 1926 to compensate for the added fuel pressure from the cowl mounted tank.

There are a couple air bleed holes on either side of the spray needle that can get clogged. The forward one can be accessed through the hole for the cork bumper and the other through the choke side.