Mattax said

I agree seems like not enough initial, but its a big engine. Do you know the cam duration?
Can look at the Barry Grant chart for a ballpark initial.

Anything that lowers 'dynamic' compression or allows more exhaust dilution at idle will need more initial.


Another thing to watch out for is the initial isn't the initial.
Easier to give an example.
Say timing is set at 13* at 1000 rpm.
Then when placed in gear, because its not making much power, rpm drops and unknown to us, the timing drops with rpm.
Now its 11* at 800 rpm. Its not making much power, rpm drops and unkwn to us, timing drops with rpm.
Finally it hits the real initial timing at 9* and 650 rpm, its not making much power, so rpm drops to 500.

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