gas mileage Mechanical vs Vacuum Secondaries

Hey:

For the record my point was never that a double pumper couldn't be driven on the street with acceptable efficiency.

I was trying to answer the OP who asked if it was true that double pumpers get worse mileage than vac secondaries (even if it only gets 1mpg worse mileage, that's still worse, yes?). I answered in the affirmative, and tried to explain why, and what is required to be done to get a double pumper to function correctly once it has been jetted down for economy.

My response about Quickfuel carbs may not be completely accurate as I have only ever owned two of them. It is possible that they have other models that would be more readily adapted to efficient street use. My response is accurate to my carbs though.

I have found that Bob2000 site to be very helpful over the years. I think that diagram can be huguely helpful to people starting out. I didn't want him to get a bad rap because of a misunderstanding about something I posted.

These are facts.

My opinion is that if I weren't going to race a car at least semi frequently, I'd run a vacuum secondary carburetor on it. A good vacuum secondary is so much cheaper and easier by comparison, especially when you live in a climate where the density altitude swings by 3500 feet or more from May to October.

I run a vacuum secondary Holley on the car when I'm done racing for the year, and when I get it out of storage in the spring. The rest of the time, it wears a double pumper.