Technical Dripping Stromberg 97s after motor shutdown

Thanks that’s interesting I wonder how a line running back to the supply line and tied into it with a T before the fuel pump would work.

 

Along with the small return line going back to the tank I would make sure the float tang is exactly vertical when pushing against the " closed" needle & seat. To enable tang to be vertical it might necessary to take a light cut off the gskt surface of the seat to allow n&s to be moved deeper toward the bowl, or a thicker gskt to move n&s further outward. Keep fuel pressure at 2 lb or less with a quality regulator, not one of those cheapy $25 regs. Install Grose type n&s, set fuel level to stock setting. If you have seepage at bottom of bowls, coat the bottoms with Seal All, available at O'Reilly's. Do all this & you will be happy. Greg

 

My return line was same size, (only temporary), but I think it should be smaller.
I have no experience with the filter I showed, but there was another thread on here about it.

 

I have this problem and was gonna get some spacers. I will be watching this one.

 

I’ve decided on an approach that I think will work really well.

I printed out a response from Clive from another thread where he laid out the requirements for a return line with a .024 flow diameter restrictor.

The purpose is to drop the fuel pressure quickly when you shut the engine down and the fuel pump stops pumping.

According to Clive a return line to the top of the tank is ideal however if that isn’t possible then the return line with the restrictor can be teed into the supply line just before the fuel pump.

I’m relocating my fuel pressure gauge to the front end of my fuel log before the carbs and will plumb the return line from the end of the log with the restrictor back to the supply line near the pump.

I’m also going to order a set of 1/4”phenolic spacer insulators and longer mounting studs from Stromberg.

I believe this will solve my problems.

 

I was out in the shop working on the car yesterday and noticed that one of my new (300 mile) Stromberg carbs had fuel dripping from the shaft and from the air screws down under the bowl. Upon further review its seeping from the Accelerator Pump Discharge tubes. I have a electric pump on the frame rail, regulator after that, up the firewall to a glass bowl sediment filter, then across the firewall to the first carb. Float level has been checked and is just under 1/2" from the top

Is this the same issue people are experiencing above? I won't be doing a return line, I have the stock A tank and don't want to mess with that. However, I can swap out the Gross Jet with a needle and seat setup to try. Its only on the rear (#3) carb. Perhaps I am overlooking a different problem?

 

Hi FiveNdime,
Speaking from my desk (ie not looking at the actual car) my first reaction, from experience, is to ask if you are switching the fuel off when you stop the car. Using a stock Model A tank is very handy and I do the same in my own 1928 AV8 Phaeton, but Henry Ford put a tap in the line for a reason. We have seen a whole tank full of gas end up in the oil pan when the fuel is not turned off. In theory, the float should cut it off, but liquids do have a habit of finding their level. And electric pumps are usually open circuit all the time.

The reason the fuel comes out of the throttle shaft bushes is because it floods up inside, exits out of the emulsion tube tips and puddles on the closed throttle shafts. It is unusual for fuel come out of the accelerator pump tubes as the power valve should be shut, but let me know if that is the case.

You can check an S-jet very easily. Just take it off the car, wash it out then blow into it like Miles Davis. When you touch the big ball in and out, it should cut the air off. If not, then please email me, Clive at Stromberg-97.com and we can sort it out.

One more thing, we do sometimes see flooding from the carb closest to the fuel pump, so check your regulator is telling the truth, and maybe turn it down a little. 97s will run great at 2psi and even lower. If you have any more queries, just let me know. Thanks...

 

Hi Clive,
I have a valve, but it's in poor shape and has a hard time closing off so I don't use it. I will pick up a new one and install it to see if that helps. I will give the S-jet a check and see if it's not sealing. Funny thing is out of the 3 new carbs, I've already had to replace one on the furthest forward since it was not sealing. Even with some gingerly taps to the ball. I am certain the fuel pressure is good, but I did pick up a 0-3psi gauge to get a very accurate reading of it. My current gauge says 1.8lbs. I have replaced all 3 power valves with genuine Stromberg ones, up 2 sizes if memory serves. Maybe I got a faulty one? Thanks for the helpful tips, I will get on this and get right back to ya.

 

The gas that’s available is crap. Really hard on carbs. Wreaks rubber seals. Even the so called carbs that have seals and O rings resistant to breakdown have problems. We get our fuel from California. With all the garbage they put in their fuel it’s a wonder an older engine would fire.

 

Perhaps where you're at, but in my neck of the woods we have decent fuel that can sit for long periods of time without issue. Non Ethanol Premium is all I've ever stuck in this thing.

I believe it to be a bad Gross Jet/S-Jet on just this carb. Since my fuel tank is above the carb it should have a shut off. Henry Ford wouldn't have put one in if it didn't need it. I have a normally open fuel pump, causing no shut off for this system after shutting down. If it were just pressure, they would all be leaking in my opinion, so my plan is to install a new fuel shut off valve and monitor the situation. Then I will replace the S-Jet if it is bad. My stock shut off is not in very good shape.

One new item I just thought about as I was typing this. For the first 250 miles on this new engine in this car this summer, I only ran about half tank and under. Recently I have been putting in a full tank every time, and keep it topped off for the most part every time I go to town. I think that maybe the extra fuel which would create more pressure is causing this. This wasn't an issue before, so I might try draining some fuel and letting it sit. I have put a clamp on the hose now while its sitting. I will keep ya posted on the findings.

 

Maybe a cutoff switch, I thought about that in my 52 Dodge. Smell gas fumes all this past summer. 108 avg temps but it’s cooling down now. Yeah, pressure in the tank has to go somewhere, maybe back filling. Have you considered a return line?

 

Another thought I had was fuel pressure when the car is running. Is the pressure overcoming the throttle shaft seals?

 

There are no seals on the throttle shaft, and no other carburetor that I know of. You sometimes see fuel exiting the shaft bushes when the engine is stopped, but that is because it is flooding in the bowl and tipping out of the emulsion tube tips then puddling on the closed throttle plates.

 

Yes, seals is the wrong term, should have termed it bushings. My thought is the carb is overcome with fuel and when stopped and residual fuel leaks out at the throttle shafts.

 

Funny, I don’t see this same thing happening with the GM carbs

 

Not a fan of the grose-jet, but do not believe it is the problem in this case.

We see this with all brands of carburetors and all types of fuel valves, so often that I did a blog on it decades ago.

Here is that blog from the "troubleshooting" section of my website:

https://www.thecarburetorshop.com/Troubleshooting.htm#Fuelleak

Easiest thing to try is a different fuel station.

Generally, if one has multiple carbs, only one will leak (the one that leaks at the lowest pressure). Once the one carb begins to leak, it will bleed the pressure such that the carbs that would leak at slightly higher pressure don't see the pressure level necessary for the other carbs to leak.

Jon

 

I lived in Yakima for 38 years, never had fuel issue until we moved to Mesa, AZ. Cali fuel. Shit is really dirty and has all that crap in in.

 

I have thought about that return line as some have suggested. Only issue I have with that, is I believe it to be a bandaid for another problem. Here is why I think that. There are many applications that have Stromberg's, and don't have a return line yet function properly. I have never been one to put bandaids on situations, or for better terms throw parts at something till it stops a problem. I try to learn and do the proper testing of components till I get an actual reason to the condition. These carbs don't care what engine they are mounted on, and I've seen them on many newer muscle cars, hot rods etc. At this time, I will order a shut off valve for the tank to replace the worn out one. I also did a test with a clamp to clamp the fuel hose closed. This stopped the issue, once I let the clamp off the fuel flowed into the float bowl on that rear carb. I'm fairly certain it's an issue with running the cowl tank up high vs a tank down below the carburetors. I might also try actual needle and set type setups for my carbs and put aside the S-jets. One other option is to put a tank in the truck as most do, positive on this is that I could isolate the front tank, use the rear tank as a main tank and the front as a secondary reserve sort of speak.

 

Wanted to do an update to show people how I solved my fuel issue. A quick review. After shutting the car off the fuel would slowly seep past the Gross Jets on all 3 stromberg 97s. It was not the jets, I tested those. It was the pressure from the stock A cowl tank pushing past. So, to solve this I purchased a 12v fuel shut off valve that's normally closed.


Put it in line after the pump. Don't mine the wiring, it's not tied up yet, but this is the setup. The pump and valve both utilize a ground from the Inertia switch. That way it will cut power to both in an accident.