Reply With QuoteYou might also check the ignition system. Ignition troubles can have symptoms like you're seeing. Along these lines maybe pull the distributor to see if the gear is OK. Along with wiped out cam lobes there has been wiped out distributor gears. Zinc additives have been removed from many oils, blah, blah. Rotella is one that still has the good additives. The diesel rated oils still have the zinc additives. I also agree that 20 degrees initial is too much. 36 total seems fine, but like in a drag car you'd fine tune that with top end MPH. The 12 initial, all in by 3200 RPM sounds good, but I don't know boats. A typical street car hot rod would probably have it all in by 3000, maybe even by 2700 or 2800. The guy that said initial doesn't matter isn't wrong. Some guys set up a hard core motor with locked in timing and that's it. As far as vacuum, you listed the advertised duration, but that doesn't tell much - it varies so much from one cam company to the next. Do you know the .050 duration? If you know that, you should be able to get some sort of an idea on vacuum at idle. You get near 250 or 260 degrees duration @ .050 and you's got a pretty lumpy cam that won't have a lot of vacuum. Also see if you know the lobe separation - it also comes into play. That number should be something like 108, 110, 112, etc. I think somebody also mentioned checking for boken valvesprings. You could do a basic check by pulling the valve covers and turning the engine over by hand. One more thing could be a bent pushrod.
