VCCA Home Forums TECHNICAL - 1945 AND EARLIER 1912-1928 Rebuilding a Carter RXO Carburetor

I'm deployed to Italy as a military contractor and I am going to be here for a few more years. I thought I would do something constructive with my spare time since we are restricted from doing very much due to the Covid virus. When I get back home to Colorado I plan on working on my car (25 sedan) so I want to gather as much information that I can while I am here. I will need to rebuild the carburetor so I have a few questions I need answers to. I know that their are probably better carburetor options to use other than the RXO but my goal is to take the car back to it's original form as much as possible. I also know that there are vendors and members that can rebuild a carburetor to a much better level than I can but I see the car as a piece of art and I would like to paint the picture myself to the greatest extent possible.

Here are some of my questions:

Disassembly - In the past I have had problems getting brass components to cooperate. I used heat but it did not seem to have much effect. What techniques could I use to remove the jets and any plugs?

Cleaning - Carb cleaner, compressed air, ultrasonic cleaner - What techniques work?

Inspection - Does the standpipe need to be removed for inspection and cleaning purposes? How do I know if the standpipe and jets are still serviceable? Needle valve - All are replacement needle valves equal or are some types better than others? Can the needle valve seat be replaced or is it in the casting?

Tools - What tools are used to removed components (stand pipe, jets)?

Paint - I read that someone uses epoxy paint because it resists gasoline exposure but I also read that it is difficult to remove once the carb is painted.

I know I will have more questions as time goes on but I need to start somewhere. If you have other information that is pertinent and I didn't ask about please feel free to contribute.

Thanks........

I believe you may have emailed a question on kit prices a couple of weeks ago.

Even though I manufacture and sell carburetor rebuilding kits, and I understand your desire to do this yourself, this is a carburetor that is best done by a professional with tons of experience on these carbs! Chipper or Junk Yard Dog come to mind quickly.

But having said that:

First acquire a copy of the factory Carter specification sheets for the carburetor.

Disassembly - before even attempting disassembly, place the carburetor in an ultrasonic cleaner and run it for at least an hour in solvent. Then do it again in water to remove the solvent. Now it becomes a chess match with the carburetor and you are going to be checkmated! Heat from an acetylene torch will loosen the brass plugs and jets. It will also destroy all pot metal parts, and dissolve the solder in the low speed jet. If heated sufficiently, the jets and plugs can then be removed with normal screwdrivers.

Standpipe - unless it has already been replaced with a new one made of brass, it is not serviceable. Period. Expect to replace this part.

Low speed jet - you have maybe a 50 percent probability of salvaging this jet, expect to replace it. If you do get it out without breaking, compare to the factory specifications.

Multiple jet serviceability - once removed, check first to see if some previous "Dr. Goodpliers" (the evil twin of Mr. Goodwrench) has destroyed the slot and/or damages the various orifices, and second that it is the correct multiple jet for the carburetor (when I first started doing these, there was a father/son "rebuilder" combination doing these, and if the part fit, it was the correct part - this was 50 years ago). Compare all of the orifices to the factory specifications.

Special tools - there is a standpipe wrench that will be handy for installing the new standpipe. Getting the old one out generally means using some chemical to dissolve the remains.

Once the casting is completely stripped, there are a number of methods of removing the rust: some prefer Naval Jelly, others sodium hydroxide, I prefer glass beading.

Fuel valves - there is a difference of opinion here. I recommend neoprene valves, and sell them in the kits we sell. Another gentleman whom I previously mentioned prefers the steel valve, and we offer these to those who request them at extra cost in the kits. The extra cost is due to our costs. Each has advantages and disadvantages. The neoprene will seal better than steel, but the tip can be damaged from rust debris in the fuel and then not seal. The steel will not be damaged by debris, but steel, even the Monel steel used for these valves WILL rust, especially if subjected to ethanol fuel. I have posted a picture several times of a very rusted ORIGINAL Carter valve. Obviously the rusted valve will not seal. So the choice here would be yours.

Epoxy paint can be removed if one uses the proper chemicals.

Don't forget to test the float - submerge in hot water. If there are leaks, you will see a stream of bubbles like an intertube with a nail!

Having typed all of the above, my professional recommendation is to have one of your friends/relatives in Colorado ship the core to either JYD or Chipper for rebuilding, and have it waiting for your when you return to the States.

Jon.

As one that Jon has recommended I will agree on his recommendations and add a little more information.

I have rebuilt nearly 1000 carburetors in the past 20 years. The vast majority are 1925 to 1931 Carter updrafts.

There are a few Carter factory tools that are critical in properly servicing those carburetors. In addition to the standpipe wrench, proper sized flat bladed screw drivers are a must. Use of loose fitting screw drivers on stuck brass parts is what destroys the slots. After that is when most send the carburetor for rebuild. I would like to thank those folks for making my job much tougher.

The other tool is the low speed jet tube puller. Probably 90% of the updraft carburetors that I receive have the solder joint on the low speed jet assembly broken or It gets melted in the heating process for removal. That requires a puller to remove the tube. Trust me needle nosed pliers don't work.

While I agree with the comparison Jon presented for the needle/seat assemblies, I need to present my preference. It is the steel needle. While corrosion and damage are a potential problem, the weight compared to the neoprene or Viton tips is why I prefer the all metal needles. Modern gasoline contains significant amounts of unsaturated hydrocarbons. There are inhibitors added at the refinery that have a limited lifetime. These unsaturates can quickly combine to produce gums and varnishes. These are very sticky and can hold parts together like the needle to the seat. In running my old Chevys I have experienced the problem on numerous occasions. A rap with a screwdriver handle or other light duty metal object often is enough to break the needle free. The gas liquid will prevent sticking until it dries out again.

A complete (not for sale) Carter tool kit from 1935 with the tools to service all of the updraft brass bowl Carters, is pictured in my virtual carburetor museum:

Carburetor virtual museum - Carter section

Jon.