Engine AF small Bore vs Large Bore
 

Recently I purchased a model A engine with the prefix AF, searching in the web I found some information in the text below... from the Ford Garage web page, I'm curious about the engine bore... Why Ford produced engines with a small bore and a large bore? What engine have more HP?

For example, engine number 1234567☆ was produced at the Rouge and might have had a prefix of ☆A, ☆AA, ☆AF, or ☆AAF depending on whether it was for a car or truck (clutch), and whether it was for a large bore engine for the US, a small bore engine assembly for export, or a RHD engine and transmission assembly produced at the Rouge for export to a RHD non-British Empire country, such as some South American countries at the time.
Non Rouge-built:
Small bore engines produced in England (RHD) used numbers from assigned number groups granted by the Rouge to the foreign engine plants, however the 'F' in the prefix was only used to indicate the small bore engine. Large bore engines did not carry the 'F' in the prefix.

For example, engine number 700001☆ was in a group of numbers which was assigned to Ford's engine production operation in Manchester, England for their use, and may have ultimately had a prefix of ☆A or ☆AA depending on whether it was destined for a car or truck. It may also have had an 'F' at the end of the prefix (i.e. ☆AF) to indicate if it was a small bore engine.

Re: Engine AF small Bore vs Large Bore
 

I have one AF block, however it has the standard A bore, not a smaller sized bore. I was told it came from an RHD Model A phaeton that was brought stateside from Australia. Rod

Re: Engine AF small Bore vs Large Bore
 

As I understand it, England taxed cars on theoretical horsepower, which was calculated from bore and stroke. So many cars had small engines, to avoid the higher taxes.

Re: Engine AF small Bore vs Large Bore
 

The way I understand it tells you from what area that it came from, as you found out that also tell were it was made. My avator is my truck that I am personal restoring from ground up. This is a production sheet for 1928.https://www.fordbarn.com/forum/attach...1&d=1309809015

Re: Engine AF small Bore vs Large Bore
 

"AF" was used two ways! In England it referred to the small-bore engine used to lower taxes based on bore size...
In USA (the source of Argentine Fords) and Canada, it designated a car built with right hand drive. Ford produced both RHD and LHD stuff all over the world, as USA and Canada supplied a number of RHD markets and England built cars headed for LHD places on the continent. There were also a fair number of RHD cars sold in the USA, apparently, ordered by rural mail delivery men!
An AF in Argentina almost certainy would be a regular bore engine built in the USA for the Argentine market.

Re: Engine AF small Bore vs Large Bore
 

Oh thanks Bruce!! you always have an answer!!...