Stroker timing changes ?

mbaird said

The point was to start a discussion explaining why the timing needs to change . Aspects like piston speed , cylinder filling, changes to DCR etc…. Many know that canges are required after a component change but not exactly why . The ability to visualize the process helps us become better tuners .

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It’s hard to give specifics because there are too many variables.

But, if you are going from say a 1.85 r/s ratio and you are going to 1.53 you will probably need 2-4 degrees more initial as a baseline.

That also depends on your compression ratio, the fuel you are using, cam timing and even coolant temperature.

You want most of the combustion cycle done by 12-15 degrees ATDC so any time you change the r/s ratio it affects ignition timing.

As a very general rule the lower r/s ratio the more total timing it will want depending on rpm and induction efficiency.

It really takes a a few hours on an engine dyno just to determine what the engine wants for a timing curve.

Then it takes time to screw around and get the mechanical curve to match what the engine wants, while keeping in mind that ALL ignition boxes retard with rpm so you have to account for that too.