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# How to choose ign timing numbers with no base map

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so watching a few of the webinars Andre and even looking at my own ecu I wonder, how do you go about selecting certain ign timing numbers if you are building a timing map from scratch. I understand that around idle most cars like anywhere from 15-20 degrees, but say on your higher rpm/vacuum zones, like the attached picture the numbers are in the high 30's low 40's. Are these numbers just inputed to make the 3D map look proportional? Thanks in advance for any replies.

This is good question. I had similar project where i converted carb to efi. I took the old distriputer initial timing and total timing and build a map based on that. It didn't work. I hope we get good feedback.

Anyone?

Copy a table from a similar engine, take 3-6 degrees of timing out from 2500 RPM up, then tune from there on the dyno.

You could also just put a value of 15 - 20 degrees in the whole table and tune it on the dyno.

Note that you can't really tune ignition timing without a dyno.

THE MOST IMPORTANT THING IS TO MAKE SURE YOUR COMMANDED TIMING EQUALS THE ACTUAL TIMING USING A TIMING LIGHT. Too many people skip this step then get all confused about what the timing table needs to be to avoid knock or achieve MBT.

If i start without a base map (megasquirt usually), i put in some reasonable numbers. For example, most engines will be fine on 8 psi of boost with around 15 degrees of timing, so i will put that in, around 25 degrees in part throttle, etc. Then i will start doing steady state tuning, starting with the lowest rpm i can do (usually around 1500 rpm). I will tune that row of fueling, and then the timing in that row according to my torque readout on the dyno. When it stops increasing when adding timing, thats mbt. I will use that row to get an educated idea of what the rest of the part throttle timing will look like, and adjust it a bit. i will then move on to the next rpm, continually adjusting the next row to what my dyno shows in the previous row. Once i get to full throttle, i will do a partial pull, maybe to 5000 rpm, just to see how the engine is going to act according to my fueling/timing numbers. From that point on, i will creep up to mbt, and pull a few degrees out depending on fuel. Thats just a brief summary of it. You cant really do it without a dyno. You can street tune it, but youll never know if you are truly at mbt, or just staying away from the knock threshold.

Hope that helped

Thanks for your input guys, I watched some worked examples on the practical tuning course and Andre explains the process pretty well. Thanks again guys

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