[wakealanche]

I just switched my PCM(Pleasure Craft Marine) 454ci engine with a yl670av Mallory distributor to a ylu624av unilite distibutor. I was wondering what the correct ignition timing should be.
It was set at 12 degrees BTDC & ran great but the manual says it should have been 5 degrees AV, 9 degrees[MV].(I assume AV relates to the suffix on the distibutor?) What should I set it at?

[DoubleVision]

I`d set it at 10 - 12 Degree`s BTDC. I think most manuals are just trying to meet emissions requirements, if you hear detonation, slow it down 2 degree`s at a time until it stops and your set.