The right side of the ACE engine |
This drawing gives a very unusual view of the ducting of the preheating tubes of the intake;
and the caption of
the picture in the magazine states :
The valve side of the engine. Observe the method of enclosing the inlet rockers and the shape of the induction pipe( Again I ask you to bear with me on the size of these pictures.) |
The 1920 Ace had the long and curved intake with the carburettor
angled across the bike like in this drawing. This is the
same consept the constructor,William Henderson had used on the
earlier Hendersons.
The long intake were prone to freezing and
condensation even in summer days and the Ace were given this
additional preheating system as shown so clearly in this drawing.
I have experienced myself how the long angled intake on my own 1916
Henderson is frosting on the outside on hot summer days when the
carburettor is adjusted down to run lean.
Later Ace got the option of a much more efficient short, straight
"Police Intake".
The casting of the all cylinder had an extra cylindrical lump on the exhaust outlet. This was for taking exhaust gas out to preheat the intake manifold on the no 4 cylinder only. The factory kept these on the cylinder castings for several years even though they quit the complicated preheating system after 1921. I am not sure when they adopted the second series of Ace cylinder casting like those shown in page 53 of Jerry Hatfield's "Indian Four Motorcycles"...... |
| Return to 1920 Ace presentation |
This took away the preheating of the intake manifold
and changed the the preheating of the carburettor slightly. The change in
construction meant a lot to performance and many Ace owners replaced
their old angled intakes with the more
modern straight ones. Not many old early intake manifolds have survived.....