could you share the number of the combination of jet/metering rod you are using?

I have a 1955 Ford Customline 2 dr. with the 272. Using the later distributor and 57 manifold. Running a jetted down 600 Edelbrock. With stick and overdrive and 4:89 gears. Got back from Montana and got between 21 and 22 mpg.

Too much or too little timing will reduce mileage since the engine will not be performing optimally.

Everything else equal, another carb generally will not increase or decrease mileage.  The reason being that the engine needs a certain a/f ratio for best performance or economy.  If the engine gets that ratio, then there will be no difference, regardless of the carb because it's getting the exact same amount of fuel and air.
There is a range that is generally acceptable for the a/f ratio of any engine.  If one carb is tuned closer to the performance ratio and the other is tuned closer to the economy ratio, then you will see a difference, but that is the tune, not the carb.
Long story short, you need to tune.  There is no such thing as bolt on and go if it is maximum performance or economy that you are after.  The best way to tune a carb is to  use an oxygen sensor.  It saves loads of time vs plug reading and allows you to see exactly what is happening in real time under various conditions, making it real easy to determine what needs to be done.  Get the book "How to Super Tune Holley Carburetors."  Obviously tuning will be modern Holley specific, but the theory applies to any carb.


Lawrenceville, GA

Assuming that the distributor is a 1957, John Mummert pointed out recently in Y-Block magazine, that the 57-58 distributors have an aggresive centrifical advance curve, because those 2 yrs specified intial at 3 degrees. Apparently setting the initial at 8 degrees or more can cause problems with detonation. Would it also have any effect on Mileage?       


Paul

My 56 292 automatic best with the stock Holley and Load-matic was 12, same with a Carter WCFB from a 53 Cadillac (small base 331") and newer distributor. Dual quads, WCFB's, get 10+, all in town driving. I'll not go back. 

56 Vic, B'Ville 200 MPH Club Member, So Cal.

I have been runnng an E dual quad setup since 1966. Worse I go was 9 around town. Best was a little over 17 on a T Bird Club economy run. Your milage may varry.

Would an Autolite 4100 with 1.08 venturies get better mileage than a stock T-pot on a 292 with Fordomatic?


~DJ~ AKA "Bleach"
1956 Ford Fairlane Town Sedan 30K original miles

My bone stock 56 Crown Vic 64B , 292, standard no overdrive, 4;10 gears (original owner towed a boat with it) gave me 10 mpg city, and about 12.5 highway. 

On a recent trip from New Hampshire to Massachusetts I gassed up on the way out of town. When I got back I noticed the odometer turned 100 miles almost exactly by the same station I'd used earlier. I decided it was a good point to check the mileage. To my great surprise it took only 5.8 gallons, that's about 17.2 miles per gallon with my new supercharged Ted Eaton motor. WOW! No massive power runs but I had to play with it a bit. Just couldn't resist a little display of acceleration now and then.

Y's guys rule!
Looking for McCullouch VS57 brackets and parts. Also looking for 28 Chrysler series 72 parts. And early Hemi parts.

MoonShadow, 292 w/McCulloch, 28 Chrysler Roadster, 354 Hemi)
Manchester, New Hampshire

Have you spent any time tuning?


Lawrenceville, GA