[mhsprecher]

I am sure there is a better way to do this, but I copied this from a post that H. L. Chauvin wrote on a recent question about a high compression head. This sounds like an interesting experiment to me:

FWIW: One humble opinion heard on one (1) vintage, very inexpensive method to increase an original Model A Engine's performance.

Model A racing engine re-builder, Mr. Ron Kelley, explained to me about many of his past experiences with testing horsepower on Model A engines on his "calibrated" dynamometer, most of which he recorded on printed charts in the past indicating horsepower and overall engine performance.

He said most never realize that one of the most effective horsepower gaining methods at the "least" cost to a Model A owner that he observed and tested is simply trying to increase the velocity and volume of the fuel mixture.

This method is related to what racing engine re-builders refer to as porting; i. e., smoothing engine interior surfaces adjacent to the where the fuel mixture is flowing.

Some Model A owners never understand and consider that smoothing the interior fuel passages to increase fuel flow is similar to one barely depresses a Model A accelerator where the carburetor butterfly throttle opens ever so slightly; hence, more of the fuel mixture is entering the combustion chamber at a more rapid rate which means the Model A engine's rpm's are increased.

This fuel/liquid/ air faster flow hydraulic engineering theory is not any different than that of using "Manning Charts" to determine the flow of fluids for designing engineered storm drainage.

For example, for fluids, because of interior surface friction, one can observe that:

A. Water flows faster in a new, clean concrete culvert than in an exterior drainage ditch full of thick grass.

B. Water flows faster in a new, ultra smooth PVC pipe than in an old very rough interior surfaced cast iron storm drain pipe.

Mr. Kelley further explained that while re-building stock Model A engines that he sees today, he observed several minor things can be done to increase engine performance only by slightly increasing fuel flow.

He recommends trying to provide smooth uninterrupted surfaces, (which causes turbulence and reduces fuel mixture velocity), where the fuel mixture flows such as:

1. Start by verifying that the interior of the carburetor venturi is smooth as opposed to having some of the earlier 1950's reproduction venturi's which had an internal lip which should be removed.

2. Verify that the carburetor to intake manifold gasket interior hole is enlarged where it does not protrude into the intake manifold thus causing turbulence. (Also, an old sagging Model A manifold with non-aligned openings at the engine block does not help to increase engine fuel flow.)

3. With a Dremel tool, smooth out the cast iron interior surfaces of the intake manifold and the engine's cast iron intake and exhaust ports. Smooth out very rough surfaces, protruding cast iron fins at corners and sharp corners; however, never cut deeply into the thin cast iron inside the engine ports such that one cuts into the engine's water jackets.

4. Remove and round off the sharp bottom lip on all valves and slightly round off the sharp top lip found on valves.

5. Insure there is no carbon build-up on the top surface of the engine block which can reduce valve opening size and fuel flow.

Just hope this can help someone some day.