Fine Tuning Your Carburetor

Although I have tuned countless carburetors over the years by “ear”, I decided I wanted to make sure I had tuned my trucks new carburetor to be as efficient as possible. Especially since my hearing is NOTHING like it used to be!

The next step in carburetor tuning is via a halfway decent vacuum gauge. You connect the gauge to a vacuum source – in this case I connected to the line right off the intake manifold that runs to the vacuum advance unit on the distributor. I immediately saw a wobbly reading of approximately 16.5 inches of vacuum. After adjusting the mixture, it rose to a little over 18 (you want to see between 18-20 or so) and was pretty steady. Also, the periodic “puff” in the exhaust decreased, which was good.

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