Old Blue (1/2 ton truck) came with a 216 ci engine and according to the owners manual (Instructions for the Operation and Care of Your 1937 Chevrolet Trucks)produced 29.4 horsepower (N.A.C.C.). Question 1. -- What does N.A.C.C. mean?

Question 2. -- The July 2005 issue of G&D has an great article by Mr. Benzel about his 1937 rumble seat coupe. His coupes 216 ci engine was rated new at 85 horsepower. I believe this is correct too as I checked another reference today and it indicated the same rating. Does anyone know why the two engines would have produced such different horsepower performance (29.4 vs 85)?
Thanks, 37Blue

Don't know what N.C.C.A. stands for, maybe a taxable horsepower rating or a predecessor of S.A.E.(Society of Automotive Engineers?)?

The two engines have the same or nearly the same horsepower, just different rating methods.

The 29.4 horse power is what was called the "taxable" horse power It formulated from the bore and the number of cylinders and means nothing as to actual power.England and perhaps other contries taxed the car according to this number...Small bore engines/cars were favored in England because of this tax.Chrysler products used special small bore engines for export-and their engines already had a small bore long stroke engine.The Hudson engine that had a small 3 inch bore and a long 5 inch stroke were also favored.A small bore version of the 216 engine was also available a few years....it was called the Cheetah engine.
I believe that this method on horse power rating/tax is no longer used.
The 1937-40 216 passenger car is rated at 85 at 3200 RPM "brake" horse power which is the actual power developed on a dyno.
The truck engines were rated at 78 horse power.The lower power was due to a restrictor plate under the carburetor to limit high RPM"S- a governer effect..This was used to discourage winding out the engine thru the gears when pulling heavy loads.Would encourage the driver to up-shift sooner-thus "saving " the engine.Was used on trucks up thru 1940.

Thanks guys for the info. Chevgene's info and George33Eagle's thought that the N.C.C.A. acronym maybe tax related seems possible. I wonder though if the tax collectors would have agreed with the horsepower calculation and interpretation.
37Blue