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Old 02-18-2012, 01:54 AM
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The reason big cams need so much initial at idle is because they are LEAN even though they can smell pig rich. Lean AFR is a very slow burn and therefore needs much more idle advance. Look at your cam card. You have a total of 69 deg overlap! (int = 37 and ex = 32.) That is a big cam that has built-in EGR! Because of overlap the exhaust gas is contaminating (i.e., LEANING) the intake and you get lean AFR as a result. Give the motor whatever it wants at idle. I suggest you weld a bung into the exhaust and buy an O2 data logger to help with tuning.

There is no magic number to give you for WOT. Every engine requires its own number and that is determined by experimentation. Look at all the suggestions so far. There are no two agreeing numbers and that is the way it should be. Every engine and environment is different. Look at all the variables like gas or E-85, winter gas, summer gas, cold morning, or hot, humid afternoon, raised compression but by how much? Look at all the suggestions and note the assorted numbers. Pick a conservative one and start testing and reading plugs. As soon as you see pepper on the insulator back off timing 2 degrees. Good luck and have fun.
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