If you go with too big of a carb, you reduce the flow rate through the carb. To move the same amount of air through a hole, the air flows faster through a smaller hole, and slower through a larger hole.
For a carb to work, it needs volocity of air flow. With low engine speeds you get less efficiency,but the throttle plates are also closed causing a quicker air flow around the plates and the idle jets then a larger bore carb would provide.
Any carb is most efficient at wide open. The problem is at wide open it also supplies extra fuel for max performance. That extra fuel has to blend and atomize well. With too big of a carb, the flow is not enough to atomize the fuel well, and you just dump a lot of liquid gas in the engine. Liquid does not burn. It must turn into a vapor. As a result performance suffers, and the engine bogs.
Without the enrichment a carb delivers the best efficency at about 3/4 throttle. Again a larger carb is not as far open as a smaller one, so it's efficency suffers, and mileage drops as well as throttle response.
The small carb is always better, until it gets too small to supply all of the engine needs. At that point efficency is way up, but performance suffers.
This is the advantage of the q-jet. The small primaries create a very good efficency of a small carb, and provides better tip in throttle response as well as better mileage in a street driven car. You in effect have a tiny carb working well for most driving. BUT when you want the power the moster secondaries open up and provide the volume needed. Needed, not excess.
On the other hand the uneven arrangement does cause a slight distribution varation of fuel to the cylinders. The rear gets slightly more fuel than the front. On a track this can slow you down a tiny bit. A Holley type carb with the same size openings at all 4 spots gives a slightly better fuel distribution at wide open throttle. So on a track the Holley design can perform better. Granted we are talking hundrends of a second. On a track that matters, on the street you can't tell the difference, but you will lose a bit of mileage and tip in, just what you need on the street.
But either way, going to big drops the car efficency, and everything suffers. Common mistake.
) Just lookin for some opinions...
