Cox Model Engine - Cylinders

Cylinders

There were a wide range of cylinders produced with three different wall thicknesses. Most are interchangeable between all engine types which can create problems when buying a used engine. All early cylinders had a thin wall which was later found to need improvement because they bent easily in a crash or when trying to undo with a Cox wrench. Some people refer to these as Mk1 cylinders. The next type was thickened at the exhaust ports and are also known by some people as Mk2. The third type was thick wall the way down from the cooling fins to the bottom. This one facilitated the exhaust throttle ring and some people refer to this as a Mk3 although Cox never referred to them like this.

Referring to the Cylinder Cross-sections above:

1. depicts a thin wall Tee Dee .049 cylinder with dual booster ports on the bypass port.
2. is a late model thick wall cylinder with slit exhaust and a single bypass booster.
3. is a Black Widow #1 cylinder with no bypass booster with a stepped wall.
4. is a pre-1955 cylinder used on early Space Bug, Space Bug Jr, Thermal Hopper and Strato Bug. Note how the thread diameter for the glow head is much smaller. No engines produced after 1955 used this cylinder.

The most powerful cylinder piston combination without a doubt is the number 4 Tee Dee 049 cylinder. This cylinder has a tapered grind and tapered and lightened piston so the piston fit gets tighter as the piston reaches top dead center (TDC). The intake or bypass porting is 2 deep ports with 2 bypass booster ports on each bypass. This setup causes a swirling of the intake fuel air mixture which promotes better combustion. The Tee Dee cylinder was the basis for the design of the Venom and Killer Bee Cylinders.