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Old 05-10-2014, 12:07 PM   #6
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Join Date: Aug 2010

Originally Posted by midnightsaint View Post
What it looks like to me,

Your wastgate allowed a little over boost notice the spike at the start then a drop. Notice a spike in the a/f ratio at the same time? You caused a momentary lean condition at that point. Not major, what boost controler are you using?

Always start tuning a car with stock cam timing. With the amount of smoothing and the choppiness of the graph, you may be have some issue in the cam set up or spark plugs getting blown out. A good a/f ratio does not always dictate no knock. Check the plugs for signs of pinging. Small pepper specks on the plugs.

Something else to add, if I remember right, the distributor on the 740 is attached to the back of the cam. When you changed the cam timing, did you reset the ignition timing? This is over looked often on these time of set ups. You advance the cam timing and advance the ignition as well(correct me if I am wrong on this could be retarding it)

You have a good set up. A little fine tuning will do wonders before throwing more parts at it.
Hmm. I see that spike on the curve now. I think I'm going to run the cam straight up and see if it helps. I think the cam being advanced, paired with the advanced timing of the chips, may be causing spark blow out. I'm using bpr7es plugs set to factory gap, with fairly new wires, rotor/cap and coil, so I know plugs are up to the task. If that doesn't help I may just try a little bigger gap on the plugs.
I was under the impression that the EZK controlled ignition timing advance, so I don't believe I advanced ignition timing when I advanced cam timing.
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