Initial Carb Adjustments

[piecesparts]

Originally Posted by myersjeremy

How can I use the vacuum gauge to dial in the carburetor? You would want it set to where it was producing the most vacuum?

Here is some info that I supplied to another individual on this forum that is looking for the same stuff that you are. See if this explains the situation enoguh for you:

First off; the air mixture screws are for the Idle circuit only. It has nothing to do with the fuel metering circuit after the transition from the idle slots to the power circuit. That is where the rods and jets come into function. HOWEVER, be careful that you do not take the engine too lean and burn a valve. You will need to spend time looking at your exhaust pipe color and your spark plugs to see if you are going to far. I skipped the purchase of a tuning kit and just bought a collection of rods and jets that went two to three steps on both sides of my factory installed parts. I now have a full set of rods and jets from over the years, but I can figure a fuel adjustment to a gnat's tail, if I want to. Do you have the original carb install book from Edelbrock? It gives the rods and jets that were in it for assembly and it gives you directions that you can go to improve on that. If not then borrow one or go to a store and copy one from a box on the floor.

Setting your idle mixture is definitely best done with a vacuum gauge connected to the intake manifold instead of by ear. Take one of the idle mixture screws in to a point that the idle drops off to a stutter and then start opening up until the idle stops increasing. Now turn the screw back inward an 1/8th of a turn. Do the opposite screw the same way. repeat this a couple times to ensure that the settings are at their best point.

Take a look at your timing and see where it is set at. If you advance initial timing some it will pick up your acceleration and take away some of the doggyness that you hate. Listen closely for detonation sounds on acceleration and also watch for "dieseling" when you shut the engine off. I timed my truck and my Son's truck with a timing light that has the advance feature on it and set them up for a TOTAL advance setting around 36 degrees. Not all engines can be set there, but you can get close.


The air cleaner is important, the more air in, the more power to work with. What height of filter element, preferrably a 4" tall one. The little short filters and a chrome cleaner assembly may be causing a turbulance issue above your carb and making you loose Horsepower. Look into a quality filter and set it up to work for you.