- Thread starter
- #51
justacanuck
Proven Member
- 118
- 62
- Dec 19, 2023
-
Cypress County,
AB_Canada
Just as I explained this, it occurred to me, this could be why our timing is out from expected: Could the intake cam timing having been advanced by 6 degrees make the whole system 6 degrees more advanced than what we measure at the crank?Yes, we toggled the diagnostic mode in ECU when checking the base timing. It looked like it was very slightly advanced when I started. We therefore moved the cam sensor, ever so slightly, to get base timing closer to 5 degrees BTDC. (unless I am misunderstood how base timing is supposed to be set)
Also, not sure if I mentioned this before, but our intake cam has a custom timing gear and it is set to ~6 degrees of advance (this may or may not be a true reflection of the actual cam position because I have not "degree'd" (?) the cam myself. I understand there may some variation in manufacturing tolerances, particularly between different manufacturers.
Based on the final numbers I am reaching, before onset of knock, I suspect we are still a few of degrees further advanced than what I could detect with our really old timing light (I suppose it may also be possible that the balancer/pulley is slightly out of alignment?)
(*edit: No. the spark occurs precisely when it occurs, and the timing light flashing on the pulley shows the result.)
Either that or the advanced intake cam must retard the timing of the exhaust cam relative to the intake cam, because the intake cam is tied to the ignition timing?
**EDIT: I'm wishing now I had reset that cam timing back to proper ZERO, before we started this, but it would be tough to set it properly with the engine in the car.
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