You wanna see small fins, look a any of the ZDZ engines
...The Model T Ford had no ball bearings in the spark advance, it was a cup mounted in front of the cam on the engine block and was controlled by a rod activated by a lever on the steering column...A roller on the end of the cam made contact with 4 metal segments connect to the coil box with wires to activate the spark ignition buzzer boxes, one for each cylinder...[8D]
My spark advance is mechanical, operated by a rod from the carb...The ball bearing is behind the hub...It is completely linear and costs about $35 less than a syncro.. The syncro spark design HAS to lag behind the crank rpm and will cause the engine to bog if the low speed needle is adjusted too rich..The lag is almost imperceptible, but can be demonstrated by intentionally richening the low speed needle...
FWIW. the Model T Ford was the most produced car in the world until eclipsed by the VW Beetle...Over 15,000,000 Model T's were produced and did very well, thank you...
