LA360 initial timing too high - are there different timing covers?

nm9stheham said

I can't see from the pix but does this engine have a choke plate on the primaries? If so and it is closed while you did this adjustment, that may explain the 19" of vacuum. Are you trying these adjustments full warmed up or cool/cold, right after start up? The engine has to be fully warmed up, and the choke plate fully open before you do this.

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It does have choke plates. The engine was fully warm and choke open when I was trying to adjust and got 19". At one point in this process, I did adjust the choke to be about 1/3 closed warm. If I recall, I could get the timing a bit lower with more choke but it was still popping out the pipes. Couldn't the 19" be the result of higher than normal idle (900-950)? I double checked my gauge with a hand pump, and it appears to be accurate.