Technical Modified Holley carb for better fuel mileage

Guy's,
Something I have worked on lately and want to share. I have been running a Chevy 250 that is juiced up a bit. The carb that has been on it is a Holley Progressive 2 BBL 500 CFM. It will give between 18-22 MPG depending on how hard I push it.
Recently took a 600 and 750 4 BBL and converted them to 3 BBL operation. Basically block off the driverside primary barrel and run it. So far I have tested both of them and am quite impressed with the performance and mileage I am getting.

The thought is: When running a 4 BBL at cruise speed. Both barrels are barely open and are not using the main jet circuit properly, using mainly the idle circuit, especially on a small engine. By using 1 BBL the main jet circuit is working and doing a very good job as a fuel atomizer.

<iframe width="560" height="315" src="https://www.youtube.com/embed/iXdFLCIz-BA" frameborder="0" allowfullscreen></iframe>

 

As soon as the throttle plate p***es the idle slot it is pulling from the main jet and power valve (depending on vacuum) circuits AND the idle circuit.

 

When they used to run the Mobil Gas Economy Run, the trick was to run such a small carburetor that you could run at full throttle and be just above the minimum speed. It was said at the time that a carburetor works best at WOT. I am under the impression that gas that is atomized or vaporized is the only gas that burns. The rest is for the air pump and the converter. So the best mileage should go to what ever atomizes the gas best. I guess what you are doing is pretty much the idea behind spread bore carbs. Small primary, big secondary. Only scaled down. If you like it it's good enough for me.

 

Interesting. Similar to the spread bore 4bbl concept.

 

Be careful with this info. I once read about a fellow that invented a carb fix like this, and Std. Oil sent 'some men in black suits' to see him. "Little ride", he was never heard from again.

 

I watched the video..He claims he has 2.56 gears..But doesn't he have a 5spd trans? I watched him shift..2.56 x od ratio can be from 2.099 to 1.76 depending on od ratio..What am I missing?

 

It is a 5 speed , but with no overdrive.
Another reason I did this, the Holley 600 and 750 are about the cheapest carbs to buy. Parts are everywhere and easy to tune.