Dirty Carburetors

[shew01]

Dirty carburetors tend to be a frequent theme on this site. Many folks post about cleaning them out to get better performance.

I remember in the late 1970s and 1980s, Citgo gas tended to plug up carburetors in my area. (I’d have to use aerosol carb cleaner to cure hesitation in my cars back then fairly frequently. I switched to BP and Exxon, and I stopped having that particular problem so often. If I recall correctly, I think these are called top tier brands and are supposed to keep the carburetor cleaner.)

Murphy (at our Walmart gas station) sells ethanol free gas, and I always add Marvel Mystery Oil when I fill up. So far, I’ve had my Model a for about a year and a half, and I don’t seem to have any carburetor issues.

I suppose not having an air filter would allow the carb to suck up more dirt. (I know there has been a lot written about the virtues and perils of running or not running an air filter.)

Was a dirty carburetor a common issue in the 1930s and 1940s?

Have you noticed one brand or type of gas causing more issues than another?

What are some ways to keep carburetors from getting dirty in the first place?


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[wwirz]

I cleaned my carburetor last fall and at the same time cleaned all the jets and replaced the gaskets. The GAV was not up to the mark so I replaced that assembly. The carb was indeed dirty but I do not know when the last time was that it was cleaned either. TO me, cleaning the carb and jets "baselined" the carb for me. I also run my A with the engine pans.
Other member in my club do not run with air filters. I try to purchase Ethanol Free when and where I can get it.
Compared to the 30s and 40s most roads are paved now....with the exception of the 600 yard long dirt road I live off of. :-)
I am not expecting carb cleanliness to be a big issue. If I have to clean it once a year after driving less than 1000 miles...so be it. A labor of love.
But I will report back at some point about how clean my carb remains. Planning, still on doing some driving at the MAFCA NH tour in June.

[old31]

The key is to make sure you have all the proper filters installed.

Pencil filter in the tank, sediment bowl screen and filter and carb filter.

With todays roads a carb air filter is probably not going to make much difference as far as filtering more particles.

[McMimmcs]

Originally Posted by old31

The key is to make sure you have all the proper filters installed.

Pencil filter in the tank, sediment bowl screen and filter and carb filter.

With todays roads a carb air filter is probably not going to make much difference as far as filtering more particles.

I totally agree with your assessment. Good common sense. Wayne

[shew01]

Originally Posted by old31

The key is to make sure you have all the proper filters installed.

Pencil filter in the tank, sediment bowl screen and filter and carb filter.

With todays roads a carb air filter is probably not going to make much difference as far as filtering more particles.

I don’t know if there is a pencil filter in my tank or not, but I’ll probably need to replace my fuel shutoff and check on that filter when the weather gets warm. It’s starting to weep just a bit.

I presume my glass sediment bowl has a screen. It seems to be collecting a little bit of dirt. There isn’t much in the bowl yet. I’ve heard they are prone to leaking; so, I’ll probably wait a while before I break it open.

The previous owner installed a carburetor filter, and the filter does collect dirt. I’ve changed it once.


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[JayJay]

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Originally Posted by shew01

I don’t know if there is a pencil filter in my tank or not, but I’ll probably need to replace my fuel shutoff and check on that filter when the weather gets warm. It’s starting to weep just a bit.

I presume my glass sediment bowl has a screen. It seems to be collecting a little bit of dirt. There isn’t much in the bowl yet. I’ve heard they are prone to leaking; so, I’ll probably wait a while before I break it open.

The previous owner installed a carburetor filter, and the filter does collect dirt. I’ve changed it once.


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To see if you have a pencil filter, climb up on the running board and shine a flashlight down the filler neck. You need to stretch a bit but the fitting on the bottom of the tank is pretty easy to see. You can look at the float on your gas gauge wire at the same time to see it it’s falling apart.

Before you remove your sediment bowl, get a new cork gasket so you can replace it. Sometimes the gasket comes off partially stuck to the glass and rips, not much good then. Worth a buck to just plan to put a new one on. Put a towel, bowl or something underneath it to catch the fuel as you loosen the bail. And turn off the gas valve at the tank first (DAHIK)!

JayJay

[shew01]

Originally Posted by JayJay

To see if you have a pencil filter, climb up on the running board and shine a flashlight down the filler neck. You need to stretch a bit but the fitting on the bottom of the tank is pretty easy to see. You can look at the float on your gas gauge wire at the same time to see it it’s falling apart.

Before you remove your sediment bowl, get a new cork gasket so you can replace it. Sometimes the gasket comes off partially stuck to the glass and rips, not much good then. Worth a buck to just plan to put a new one on. Put a towel, bowl or something underneath it to catch the fuel as you loosen the bail. And turn off the gas valve at the tank first (DAHIK)!

JayJay

Really? I’ll need to check that out when my tank is low again.

And, I’ll need to order a cork gasket. I recently ordered a replacement shutoff valve, a pencil filter, and some spare gas lines (in case I need something up when I eventually take it apart in warmer weather), but I didn’t think about the sediment bowl.


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[Jacksonlll]

When you have those carburetors off to play with them, make sure that top flange is flat. Hit it with a large file to make sure.

[wwirz]

Originally Posted by Jacksonlll

When you have those carburetors off to play with them, make sure that top flange is flat. Hit it with a large file to make sure.

Yes. I saw your video on YOUTUBE

[Mike Peters]

I suspect that dirty carburetors were indeed an issue back in the 1930's. Otherwise, why are there so many Tillotson and other aftermarket carburetors on Model A barn finds? Back in the day, it was easier to replace the Dirty Zenith with a nice new Tillotoson for 5 bucks, or whatever the price was back then.

[shew01]

Originally Posted by Mike Peters

I suspect that dirty carburetors were indeed an issue back in the 1930's. Otherwise, why are there so many Tillotson and other aftermarket carburetors on Model A barn finds? Back in the day, it was easier to replace the Dirty Zenith with a nice new Tillotoson for 5 bucks, or whatever the price was back then.

That’s an excellent point. I hadn’t consider that.


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[65f100]

does anyone use an in line filter bettween sediment bowl and carb?

[old31]

Originally Posted by 65f100

does anyone use an in line filter between sediment bowl and carb?

No, that is something you really don't want to do. You don't need more points of failure next to the exhaust, plus it looks goofy.

I have had better luck with Snyders vs the wix brand #33039.

https://www.snydersantiqueauto.com/P...earchByKeyword

[ericr]

Originally Posted by 65f100

does anyone use an in line filter bettween sediment bowl and carb?

I do.....

[Patrick L.]

Originally Posted by ericr

I do.....

It was one of the first things I did. I use a filter in the line inside the car so its less noticeable. Many say that doesn't/won't work, so, just don't tell my car that. Its been running fine like that since 1975 so I don't want it to get any bad habits.

[Tacoma Bob]

I tried every bit of advice and was collapsing the "micro filter" inside the sediment bowl. Someone suggested that these motors get angry when over filtered. I tend to agree. To each his own but the best combination for my car has been the pencil filter and a wix brand #33039 inside the sediment bowl. That's it other than the useless (imho) filter inside the carb itself.

[Ruth]

Originally Posted by Tacoma Bob

The best combination for my car has been the pencil filter and a wix brand #33039 inside the sediment bowl. That's it other than the useless (imho) filter inside the carb itself.

I run the Wix 33039 filter in the sediment bowl also.

[Ernie Vitucci]

Good afternoon...Some of us in the desert simply put a good sized magnet in the glass bowl and let it pick up the rust as it comes through. It is easy to see when the magnet is full of 'stuff' and you need to open the fuel filter and wipe off the magent and clean the bowl...works well...doesn't cost much...Ernie in Arizona

[Patrick L.]

I spent a lot of time in years past cleaning carburetors, carburetors of all sorts. I don't think its too much of an issue today.
It does seem to be a pretty big topic here though. Once a carburetor is properly cleaned and adjusted they should bullet-proof for along time.
As for an 'A' carb, whatever type it is, I run different ones at different times just for the heck of it. An 'A' is an 'A', they don't much care. In mine I run all the old stale gas I have hanging around from the mowers, weedeaters, outboards, chainsaws, etc. It doesn't care. But, I do use non-ethanol in those engines. When I pull in to a station for fuel with the 'A' I use the cheap ethanol stuff, there isn't much that can hurt our carburetors.
I'm one that uses an air filter and an in-line fuel filter.

[shew01]

Does a carburetor tend to get dirty (on its own, maybe with corrosion of some sort) if it’s just sitting for a few years? That might help explain the frequent topic—often the posts are related to awakening a Model A from a long “sleep.”


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