40° is alot of WOT timing even for a low compression engine like a AMC Jeep V8. I would pull it back a few degrees on the top-end. Even without knocking it can actually hurt performance to have the timing over advanced. Was looking at an AMC 304 timing curve in a service manual the other day helping a Jeep TBI conversion guy with his rig. It had a factory spec of 35° @ WOT.
Edit..Said 30° but that was ignoring the 5°
This is what I ended up with on the 304 and it ran really well. The timing was set at 5° per the stock emissions label to prevent future confusion. I set the initial value in the ECM for 5°.
5* initial
Started the centrifical advance at 1,200 rpm, quick rise to 16° by 2,000, then on to 30° "mechanical" @ 4000 RPM
15° vacuum: start @ 6", fully advanced @ 13" in a straight linear line.
Gives the truck 35° total at WOT and 47° at cruise. ECM whacks the EST advance to 42°. 42° plus 5° is 47°.
Probably could have added a few degrees and run higher octane gas but what is the point? It runs great on 87 so why mess with it.
304 is stock save for a tiny RV cam, headers, duals and the TBI conversion. Probably could have dialed in more initial, kept the same idle timing and brought the advance curve in more quickly but as it was it would blaze the tires in the CJ at will in 1st gear.
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