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Old 10-03-2012, 02:01 PM   #107
roger 04 rt OP
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Joined: Nov 2011
Location: Massachusetts
Oddometer: 2,254
Originally Posted by rutard View Post
Have you seen Poolside's - Timing Adjustment How-to? It's not a dynamic change, but may allow you to shift the curve.

Keep up the good fight!
Yes, I did see it. Quite an ingenious way to set the static timing.

Looking at the scatter-plots a few steps back and given that the timing varies from 5 degrees or so (at idle) up to almost 45 degrees of advance (at high rpm and middle throttle), I don't feel I know enough to make a shift of the whole curve.

However, a richer mixture does burn faster (I'm 6% richer than stoic at the moment) so it may be that I have advanced the point of peak cylinder pressure somewhat (chart of flame speed below). So I guess one could argue that I should retard the timing curve a bit since I've richened the mixture. Or maybe I should just accept a bit of advance and some additional part throttle power that I've gotten from sliding the dotted line to the left (second chart below).

Originally Posted by mouthfulloflake View Post
Let me pile on the thanks, and accolades Roger, great info!

I fully retard my HES plate a while ago to try and reduce the pinging I get with low octane fuel in the summer months, it really made difference that I could tell in the pinging, but I do feel like I lost some low end 'snap' from the engine.
Thanks. Any idea how many degrees you moved the timing by rotating the plate the way you did?

roger 04 rt screwed with this post 10-03-2012 at 02:08 PM
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