Tech Corner: Carburetor Rebuild Tips

Tech Corner - IntermediateWhile much speculation surrounds the exact date–or even who exactly invented it–the carburetor appeared in the world sometime in the late 1800s. They remained the standard for a good hundred years until the adoption of fuel-injection in the late 1980s/early 1990s. But even though the past thirty years haven’t seen production cars with factory-installed carburetors, they are far from uncommon. Many still exist out there in the paved wild, and chances are you’ll even come across a few in your lifetime. And if you happen to purchase a vehicle with a carburetor, you’ll need to regularly maintain and likely even rebuild it. Additionally, if you’re looking for enhanced performance, carb modifications are a handy solution.

Little Effort, Big Reward

Carburetor work is some of the easiest and most rewarding that you can take on. It’s often a one person job that can be accomplished in just a few hours. There’s no majorly frustrating or tedious work involved, just patience and some mechanical know-how. And by the time you’re done, you’ll likely notice night and day differences in the way the engine is running.

Identifying the symptoms for a carburetor rebuild are pretty straightforward. A good rule of thumb? If you’ve recently picked up a car equipped with a carburetor, you should plan on rebuilding it. You don’t know how long that vehicle has been sitting unused, and what kind of crud has built up thanks to evaporating fuel or deteriorating parts. Likewise, if you’re finding leaks or are experiencing a stumble in the throttle, you should consider cleaning up and rebuilding. Carburetors work with really tight flow tolerances, and any sort of compromise to those tolerances will cause you a headache. Long story short: it’s worth your while to occasionally replace gaskets and clean up the internal workings of the carb.

Keep It Clean

All carburetors are different, so the exact procedure required to tear them down and perform a proper rebuild will vary. However, the general plan of attack often remains the same, regardless of model. What you’ll be looking to do is replace any gaskets, pumps or seals that may have deteriorated, and clean up the larger metal components as best you can. Depending on how filthy it has become inside, you may have to use different levels of cleaners.

For a quick job, carb-cleaner out of the can will do just fine. However, that really only takes care of the big stuff. There are a lot of buildups of grime that aren’t visible to the naked eye. If the carb you’re working on has been hard-used or is long overdue for a cleaning, you should consider soaking the parts overnight in a chemical solution. You can pick up kits specifically for this from your local parts store. This step will allow the cleaners to soak in and break down any deposits that have built up over time. If you’re looking for the extra piece of mind, there’s nothing wrong with performing this step on any carburetor you are rebuilding.

Movin’ on Up

When it comes to modifying a carb, OEM styles can be limited to the options available to them. Because of this, many builders will likely swap to an aftermarket carburetor, as they can be easily dialed in. If you happen to be working with an aftermarket carb, like a Holley double-pumper or something to that effect, you may find that you can heavily modify the platform. And in this situation, throwing in modified parts as you work may not be a bad idea. You’ll already have the carburetor torn down completely, so making the swap will require no additional steps. Metering blocks, floats, float bowls and even the main body can all be replaced. Often, hot rodders will focus on upgrading the jets and changing the sizes of the diaphragms. You can take it that extra step if you see fit.

A Word to the Wise

The most important thing to keep in mind when performing a carburetor rebuild is organization. More often than not, you will find yourself inside a carburetor because of dirt and debris. You won’t be doing yourself any favors working on one in anything short of a clean and controlled environment. Additionally, consider marking hoses and connections, or snapping a picture before you begin disconnecting things. The last thing you want is to find yourself with a bunch of sparkling clean parts and no idea of where they go. Also, consider doing the rebuild on a large pan or a surface with clear edges. If a ball bearing jumps out, you’ll be amazed–and dismayed–at how far it can roll.

Ultimately, take your time and enjoy yourself. This can be a fun and enlightening job. It’s relatively easy to do and when you’re done the reward is instant. Not too many things in life work that way but hey, maybe that’s why we love cars.

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