155 commercial timing

[cdoliver]

Hi, I've been reading up on the 155 commercial. I have a 1990. I'm trying to set it up correctly. I understand that it was intended to run on 75 octane and the timing is set to run that octane. I'm using this motor for recreational purposes and will only use 87 octane. The airbox cover says 28 deg. Is this correct for 87 octane? Should I adjust it? Also what should the RPMs be WOT for this motor. I assumed 5800, but I can't seem to get there (I'm only getting 5000 with a 21p) without going to a 17p on a 18ft bass boat... I'm thinking the gear ratio may be for the V8... Thank you for the info.

 

[Benny1963]

Re: 155 commercial timing

the sticker on the air silencer is usually right ,my 1983 150 149 cid
is setup at 28 i believe some of the commercials had different gear ratios
check your cav plate setup you may be able to pick it up a hole start flush
with bottom of transom and move up one hole at a time watch water pressure