The Ford Barn

john charlton · 06-14-2017, 12:17 PM

You are right the 3" bore AF engine is much smoother than a 24 HP engine ,due to less rotating weight etc etc . The bottom end is the same but smaller pistons and lighter con rod ( wrist pin end more narrow) make the difference . The AF engine produces 28 BHP at 2600 RPM which is OK on the flat but in hilly country you can really feel the difference . Luckily Suffolk is fairly flat !!! . Because of higher operating speeds the AF engine had a propensity to fret and eat the fibre timing gear . This brought the vehicle to a halt and the timing gear then changed . As the sump remained on no one thought to check the oil pump pickup filter and after a few timing gear changes the filter screen would get completely blocked with Celeron fretting debris and then terminal engine failure .I have taken oil pumps out of dead AF engines to find the oil pump screen covered with what looks like a dense brown felt layer .After WW2 24 HP Dagenham B engines were plentiful as they were used in generator sets and many other applications etc etc so the AF motor was changed for a B ,The "HP Tax" had been abolished so no extra tax for a 24 HP engine . The rear end also had to be changed to 3.78 to 1 . from 4.55 to 1 .

John in sunny warm Suffolk County England .

06-14-2017, 12:17 PM	#23
john charlton Senior Member Join Date: May 2010 Posts: 1,343	Re: A little film you might enjoy You are right the 3" bore AF engine is much smoother than a 24 HP engine ,due to less rotating weight etc etc . The bottom end is the same but smaller pistons and lighter con rod ( wrist pin end more narrow) make the difference . The AF engine produces 28 BHP at 2600 RPM which is OK on the flat but in hilly country you can really feel the difference . Luckily Suffolk is fairly flat !!! . Because of higher operating speeds the AF engine had a propensity to fret and eat the fibre timing gear . This brought the vehicle to a halt and the timing gear then changed . As the sump remained on no one thought to check the oil pump pickup filter and after a few timing gear changes the filter screen would get completely blocked with Celeron fretting debris and then terminal engine failure .I have taken oil pumps out of dead AF engines to find the oil pump screen covered with what looks like a dense brown felt layer .After WW2 24 HP Dagenham B engines were plentiful as they were used in generator sets and many other applications etc etc so the AF motor was changed for a B ,The "HP Tax" had been abolished so no extra tax for a 24 HP engine . The rear end also had to be changed to 3.78 to 1 . from 4.55 to 1 . John in sunny warm Suffolk County England .