[BRENT in 10-uh-C]

I think there are some confusing statements being tossed. First off, it is my opinion that an oversized Model-A intake can be a just as good, --if not better than a stock 'B' intake manifold. I think much of it has to do with the size of the manifold draw tube. Originally a Model-A manifold was 1.000" rough-cast. The Model-B intake was 1.250 machined, ...and I personally take mine to 1.300" in size. Therefore if someone bores an 'A' manifold to a smaller size than the 'B' manifold, I think it is an accurate statement than an 'A' will not flow as well as a 'B', however if it has been bored larger, then it is at least equal if not better. A stock Model-A manifold is fine if it is reamed, --OR bored 2" above the throttle plate IF a Model-A carburetor is mated to the manifold, however when a 'B' carburetor is mounted onto one of those manifolds, this method has the opportunity to slow the velocity down in the larger 'B' venturi. Also, if the larger 'B' carburetor is mated to a smaller sized manifold, there is a potential for reversion which severely limits the air flow up the draw tube as there is constant air flow interference. Porting just for the sake of enlarging is usually a detriment if it has not been R&D-ed with a manometer to find where the change in airflow is most needed.

I did not want to touch on this earlier to avoid confusion but the cylinder head compression does not necessarily mean a larger intake size would benefit the engine. This larger manifold/carburetor is affected more by camshaft design. After a "larger" camshaft, ...the size of the intake valve affects the need for more fuel & air flow.

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