This got me wondering what governs the ignition timing and why a particular setting is chosen by the engine manufacturer.Kevin Birch wrote:It sounds like timing, if it was ok until it was tuned. I set my timing as per the book, and got it spot on, 5 degrees advance at tickover, with 38 degrees maximum advance above 2500 revs, with both vacuum and mechanical advance working as they should. The car lost power, and the temperature just kept going up and up. Increased the advance by a couple of degrees at a time and the power came back in and the cooling went back to normal.
Interceptor Mk1 with "B" series engine: 12½ degrees, with "C" series engine also 12½ degrees, with "D" series engine now 5 degrees. Interceptor Mk2 with the "E" series, also 5 degrees. What is the difference between these engine series particularly between the C and D that would change the ignition timing value? Very little that I can see.
All have the same compression ratio of 10:1. The "B", "C" and "D" have the same camshaft part number, the "E" has a different one. All use the same inlet valves.
Each engine series has a different carburetor. The "B" series has the Carter AFB 4131S, the "C" series the AFB 4299S and the "D" series introduces the AVS with the 4401S and the "E" has the AVS 4682S
So, among all this, what influences the ignition timing settings?