Flow Testing Model "A" Carb Jets

B

Bill Lee/Virginia

Senior Member
Most previous carb jet flow testing puclications show the "Flow Tester" water column at 36 inches. Recently, several times, I saw comments/writings that show the water column at 36.25 and 37.25 inches. Is this due to modern fuels consisting of 10-15 percent alcohol? In addition, have the suggested flow rates of the Model "A" Ford carb jets been changed to compensate for the alcohol in today's fuels? Thanks in advance.
Bill Lee/Virginia Peninsula
 
Bill Lee/Virginia said:
Most previous carb jet flow testing puclications show the "Flow Tester" water column at 36 inches. Recently, several times, I saw comments/writings that show the water column at 36.25 and 37.25 inches. Is this due to modern fuels consisting of 10-15 percent alcohol? In addition, have the suggested flow rates of the Model "A" Ford carb jets been changed to compensate for the alcohol in today's fuels? Thanks in advance.
Bill Lee/Virginia Peninsula
Click to expand...


I wouldn't fool around with the original flow range of the jets just because of a little ethanol. If you need a richer mixture adjust the carburetor adjusting rod.

According to an old carburetor expert named Al Blatter, who worked at Bendix on fuel controls and also knew people who were employed at the original Zenith Carburetor plant, the original flow range was full rich.

Or in his words, "Our experience with carburetors using the original calibration is that the engine is full rich. We suspect the gasoline produced 50 years ago (written circa 1980) was of lower quality than today's fuel. In addition, Ford probably tended to require the rich setting to insure better driveability in cold weather."

So unless someone has run a test to prove otherwise, the fuel of today may be getting closer to the fuel in the Model A days, in some respects, and the original flow range is about right.


Larry B.
 
Last edited:
Thanks Larry for the info and advice BTW, I have one of your HC heads on my speedster and it runs smooth and powerful. Also, many thanks for your interest in building a better mousetrap for our Model A Fords. Sincerely,
Bill Lee/Virginia Peninsula
 
You must log in or register to reply here.
Back
Top