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Rebuilding Common Classic Jeep Carburetors

Posted in How To: Engine on November 7, 2014
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OK, we know what you’re thinking: True carburetors are old news, not all that efficient, can’t handle elevation changes, don’t like bumpy roads, and won’t do steep climbs. So, what’s the point? Carburetors have been around since the invention of the internal combustion engine back in the 1860s and are still in use today. Since the introduction of fuel injection, unless you’re a circle track racer or work on small engines, carburetor tuning and repair has largely turned into a lost art. Some of our best memories are when dad taught us how to rebuild carbs back when we were still playing with Match Box cars (we still play with them—don’t judge). To this day, we can still rebuild a Rochester 2G blindfolded. We shudder at the idea of a father and son bonding over a lesson in how to charge the family Prius. Ugh…

If you don’t have a lot of experience with carbs, the Rochester 2G is an excellent starting point. The 2G series is hands down the easiest carburetor to rebuild. The great part is there are no complicated air bleeds, check valves, or metering rods. Everything is integral.

The Carter WCD is only slightly more complicated than the 2G. With the addition of metering rods, you’ll have several extra-small parts. Often times, a lot of these small parts are not included in kits, so you’ll want to keep close tabs on them. If you have cats or small children, you may want to grab a few sandwich bags (ask us how we know).

The Carter W-O is the granddaddy of Jeep carburetors and has to be by far one of the most complex rebuilds we’ve ever attempted. We recommend, when pulling this carb apart, having plenty of clear space on your workbench and your camera handy.

When pulling apart your carb, it’s a good idea to take note of anything that looks out of the ordinary. However, if this is your first time, you may not know exactly what ordinary is. If you have this much rust and sediment in the bowl of your carb, you have two problems: Your fuel tank needs serious attention, and you can just about guarantee this garbage is going to be in everywhere in your carburetor.

So now we know why we couldn’t get this Jeep to idle and why it sputtered and hesitated when cruising. If there is this much sediment sitting in the bowl, it’s a safe bet its plugging the tiny idle-air circuits and probably every other part of the system.

What you’re looking at are the idle-air adjusters, and as the name implies, they control the air-fuel mixture at idle. This is an all-too-common problem, as these adjusters are made of brass, which is soft and easy to damage. What probably happened is the last person to make adjustments on this carb was inexperienced and used a screwdriver to bottom out the adjusters and torqued them down too tight. To avoid this, we just use our fingers. The mixture screws have knurled heads to make them easier to grip.

It’s always good to check everything for signs of wear. Wear on the needle shows up as a small groove around the rubber tip. If your needle has a groove like this one, it’s time to replace it; otherwise, fuel will keep leaking into the bowl. We’ve experienced the extreme case where the bowl filled to the point that it was shooting out the vent, causing the Jeep to flood and stall.

A good kit will come with everything you need to replace commonly worn parts. From the looks of it, this accelerator pump had never been changed. Good thing our kit came with a new one.

Sometimes, with these old carburetors, certain parts can be difficult or even impossible to find and you’re stuck practicing your MacGyver skills. Luckily for us, with a little fine grit sandpaper, some steel wool, and a little patience, we were able to polish out the groove in the idle-air adjusters (another reason the Jeep wouldn’t idle).

When setting the float level on a Rochester 2G carb, you measure from the top of the gasket to the soldered lip. With the bowl cover turned upside down, the measurement between the gasket and the soldered lip of the float needs to be 15⁄32 inch.

When setting the float level on a Carter WCD carb, you measure with the gasket removed from the machined gasket surface to the lowest portion of the float. The WCD has two floats attached to the same needle so it’s important to check both sides. With the bowl cover turned upside down, the measurement from the machined gasket surface to the bottom of the float should be 3⁄16 inch.

Adjusting the Rochester 2G accelerator pump is fairly simple. With the idle screw backed completely out, place a straightedge flat on top of the air horn and measure from the flat edge to the top of the linkage. The measurement you should have is 11⁄16 inch.

Adjusting the Carter WCD accelerator pump with the addition of the metering rods is slightly more complicated. Both adjusters for the accelerator pump and metering rods are located on the same cross shaft. With the idle screw backed completely out, loosen the set screw on the metering rod adjuster, bend linkage until the top of the accelerator pump linkage is level with the edge of the pump well. Now that the accelerator pump is properly adjusted, check to be sure that the metering rods are bottomed out and retighten the set screw.

Unfortunately, we were unable to find any information on how to set the float level or metering rod. As such, we just didn’t change any of the adjustments in the pump and metering system and just matched the length of the new accelerator pump linkage with the old. If we have issues, we’ll just have to make adjustments the old-fashion way—by ear.

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