Improving MPG

If you are humbled when your “A” buddies brag about getting >20 MPG, chin up as 10/15 MPG is about average or about ½ the average of your daily driver.  If you are getting less than 10 MPG here are several options:

OPTION 1 – Lie about it!  This is very effective if you seldom drive the “A” and acceptable to most gear heads.

OPTION 2 – You should road check your speedometers calibration.  Many “A’s” are equipped with 4:11 gears instead of the standard 3:78 ratio.  Jack up one wheel, chalk mark the tire and fan pulley and count the engine revolutions to one wheel revolution.

OPTION 3 – Installing the aftermarket air filters reduces mileage by about 1/3, worsening as they become clogged in a few miles.  They eliminate dirt contamination but rich mixtures dilute the oil causing excessive wear.  The rich mixture is caused by a pressure drop downstream from the filter.  Some owners overcome this by using a larger cartridge such as CA3445, and I have seen some install a vent line from a drilled port just ahead of the choke valve to another to the top of the float chamber, plugging the original float chamber vent.   This looks OK.

OPTION 4 – Carb jet orifices MUST be to specs (see chart).  Most old jets have been opened up by improper cleaning, flow increase horrendously if a few thousandths over spec.  Always check new jets before installing.

OPTION 5 – Invest a couple social security checks in an aftermarket overdrive and/or 3:45 gears.  The payback in increased gas mileage is about 354 years, reduces RPM from 10 to 30%, less power on hills and reduces braking efficiency.

If all of the above does not work, go back to OPTION 1!

This tech tip was originally provided by Pete Amsler and printed in the June 2000 “A” Quail Call.

Bookmark the permalink. Both comments and trackbacks are currently closed.