What is wrong
 

Ok so we just repowered my boat. 94 sunsation dominator. Bravo 26. 6 1/2 deep drives. Last year we ran 489 9.6:1 comp 284hr cam 230/236 .547/.547 lift l29 heads with stamped rockers air gap intake and quick fuel 750 carb. Pertronix marine distributors. Max rpm was 5100 at 72mph with roughly 400hp @28 max timing

This year we have 489 8.2:1 comp crane 741 enginequest 320 heads, crane gold rockers, victor jr intake, quick fuel 750, kn filters with stub stacks, pertronix distributors. Max rpm 5100 at 72 mph. Timing at 34 currently afr 12.5 Wth is going on. We should have 120-150 more hp per side. Im all ears

I had to read that twice looking for which blower. Why 8.2:1?

We are set up to run blowers in the future. It is a hard runner, much quicker than previous year build. My peak should be at 55-5600. Do I need to bump timing up to 38-40?

The first set up was doing pretty well considering the use of truck heads . Its hard to make big power even at 489 cubes , with 8 to 1 compression ratio. But for mow you should def be safe with 87 octane until the blowers go on

Dropped compression almost a point and a half and put in a bigger cam and went to a single plane.

Prob needs more carb.

Dropped compression is minor as it is only a 3% difference in power per point. Old heads flowed 255 at .600. Now we are at like 345. Also I took into account of compression when comparing to 525efi which is 8.75:1. Same cam. Way better heads. Weak carb. Im almost thinking carb and timing increase. Does the general rule of 1 degree advance equals 1 percent hp gain on bbc

How big griff

Got a buddy with 489's with Brodix BB-2 heads. Not sure on cam. Merlin intake. 850 Holley 4150's with the towers cut off. 35- 36 degrees timing. 89 octane. 5,200 - 5.300 RPM. Pushes a '96 303 SR-1 to 75 - 77 MPH. Way less efficient and heavier hull than your Dominator.

How far can i lean on my timing with 8.2:1. I am running 87 now but am not afraid to run 91. Also im running comp lifters set at 3/4 preload. Could that be an issue