Tricks to clean up carburetor internals without removal?

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Gasbuggy

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Aug 26, 2009
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I'm working on a 51 Ford Victoria with a Flathead and twin carbs. I last had it running 6 years ago, probably it's first start in a couple years then. At the time I drained the gas tank and put fresh 93 in it.

Repeated the process here and it did fire up quickly in cold weather but I'd like to give the carbs a bit of extra treatment. It has a external low pressure fuel pump so I could mix up something like B12 or seafoam at a real high concentration and let it run off a rogue gallon of gas.

Let me know what you guys think. I've never had one of these old ford single barrels apart and don't want to go do a rebuild unless I have to.

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What are you trying to do, get the gum and varnish out of all the little passages in the carb?

What you propose is a good step. I'd finish with some good stabilized E0 "normal" gas, or AVGas if you can find it. Then drive it more.
 
eljefino said:
What are you trying to do, get the gum and varnish out of all the little passages in the carb?

What you propose is a good step. I'd finish with some good stabilized E0 "normal" gas, or AVGas if you can find it. Then drive it more.
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Correct, I figured it has to have some build up. Finding ethanol free fuel around here requires a day trip and I only know of it being available in 89 but with 8:1 compression, lower octane should be better.

Does anyone know if shutting it down and letting it sit with a high concentration of something like seafoam/B12 in the bowls would be an issue?
 
Gasbuggy said:
Correct, I figured it has to have some build up. Finding ethanol free fuel around here requires a day trip and I only know of it being available in 89 but with 8:1 compression, lower octane should be better.

Does anyone know if shutting it down and letting it sit with a high concentration of something like seafoam/B12 in the bowls would be an issue?
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B12 is quite harsh. It will dissolve epoxy paint if used undiluted. And can soften gaskets.

Diluted per instructions, it is probably safe, but in a high concentration, I'd avoid using it long term. Accelerator pumps and flexible seals could be at risk.
 
I'd be cautious about aggressive additives and will second the recommendation for avgas, leaded or unleaded. It has worked well for me with an older inboard that sat for years and had a slight stumble on acceleration. I'd probably avoid long term use of leaded avgas if you are running synthetic oil though.
 
Lubener said:
You really can't do a thorough job with a disassembly.
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That will have to wait. It is running ok, the odds of creating a new problem with disassembly is too high and other more important issues need attention first. Like it's failed air ride suspension, and some unfinished Ron Francis wiring.
 
eljefino said:
What are you trying to do, get the gum and varnish out of all the little passages in the carb?

What you propose is a good step. I'd finish with some good stabilized E0 "normal" gas, or AVGas if you can find it. Then drive it more.
Click to expand...
I'll second the avgas. Unless it has been rebuilt with hardened valves and valve seats. BG44K was what the vw dealership used and I've read it's supposed to be up there with Techron.
 
I consider myself a carburetor shade tree enthusiast. On both motorcycle and automobile carbs I have never had a pilot or low speed jet 'unclog' itself simply by driving it with seafoam, B12, E0 fuel, STP, etc. additive in the tank.

The low speed jets are usually what clog up first with fuel residue because they are the smallest sizes, usually .020"-.030". Most motorcycle carbs have a 'pilot jet' which will clog up causing hard starting, won't run right without the choke pulled out, and weak part throttle acceleration. Once past that area full throttle usually runs ok as the main jet is much larger and does not clog as easily.

On Edelbrock and Quadrajet carbs the idle feed tubes are small, say .030" ish and sit near the bottom of the fuel bowl. They are the first things to get clogged up too and cause the same problems described above. On a Holley modular carb 4150/4160 the idle feed restriction sits in the metering block below the fuel in the float bowl level and clog in the same manner. Also on a Holley the air bleed passages like to clog as well.

I make a few bucks cleaning out pilot jets for people who let gas sit in their carbs more than a few months. I always take the carb float bowl off or the metering cluster out to unclog these pilot/low speed orifices.
 
How was it running when you started it? Hard to start or fire right off? Idle smooth or rough? Throttle response? If all this is good and smooth, I wouldn't worry too much about trying to clean something that may not need it. As said, those low speed jets and orifices are pretty small and varnish, clogs or dirt show up really quickly with poor idle and throttle response. Maybe try just some Techron or other fuel system detergent with PEA and see where it goes.

It appears you store it indoors and that helps, but fuel will still break down and absorb water even inside. You may want to consider turning off the fuel pumps and let it fuel starve to keep as little fuel in the bowls as possible. Either drain tank completely or fill to top and stabilize. My favorite is Ethanol Shield and it does a great job of emulsifying water, prevents oxidation, and has corrosion inhibitors. All my OPE gets it and never a problem. You can find it in the garden section of Walmart.
 
If the car runs well now, best get the old gas out and run fresh. Additives in the fuel will “clean up” everything and that cause more issues than you may think you have now. Not sure but those look like Stomberg carbs. There are kits produced with materials that withstand ethanol fuel.
 
When I met back up with this car I drained the fuel tank completely, removed the plugs, shot some fogging oil in the cylinders just in case but all seemed well. It has a petcock on the gas tank. I put the old gas in my Accord. It had definitely began to yellow but I've seen worse.

Luckily it has been in a garage that stays warm in the winter.

It fired off quickly and seems to idle very well but revving can be hit or miss. The linkage is set in a way that the rear carb seems to act as a delayed secondary. It does not want to stall out though.
 
I'd try Seafoam. Its cheap and shouldnt hurt anything. I've used it on gummed up carbs and if its not too bad seems to work well enough to get running well. Its worked for me in small engine carbs and those are tiny passages.

Paco
 
As others have said, ethanol free gas. I can't find ethanol free in my area buy I can get 110 octane race fuel. The high octane will just be a waste but it won't cause any problems....and race fuel is ethanol free.

But what will really help is driving it! Not just idling it around town, and not beating on it...put some good miles on it and let her get good and hot. Get some Gumout with Regane as a fuel system additive. It has PEA in it which is the best at dissolving gunk and cleaning things up. Use a double dose for every full tank.
 
Gasbuggy said:
Finding ethanol free fuel around here requires a day trip and I only know of it being available in 89 but with 8:1 compression, lower octane should be better.
Click to expand...
I don't think that is true, octane shouldn't matter. High octane stuff should be fine.

These carbs, they're on the simple side, no? Not Quadrajet complicated, right? I'm wondering how hard it is to pull a bowl off and see what it looks like, if the needle and seat are fine, if any sediment exists. Seems like that's just a gasket or two. All looks good, call it done. Looks ugly, then just bite the bullet and rebuild. I think you can pull the top off without pulling off from the engine? might be unwise, but it's more gaskets to replace if you pull of altogether.

You put in 93 octane 6 years ago? Unsealed fuel system? An 8:1 flathead might run on what is left behind... I'd be tempted to buy a click-clack 12V fuel pump and pull the fuel line off the fuel pump, then pump out a few ounces of fuel from the tank. If it smells like varnish, then plan to empty. If it's actually ok, maybe run it. Old gas can gum up valves so I'm not crazy about it, but maybe I'm over thinking it.
 
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