I have an 88 Formula 242 LS with the 454 Mag. Timing spec is 8 degrees before top dead center at idle. Would I gain any performance by advancing the timing?

idle timing means very little. 31-32 degrees at 3500 on up. any more will greatly shorten piston life.

Possibly for a minute or so you may gain 1, maybe 2 mph. Then you might be pulling the engine to replace pistons, valves, and other things.

Leave it set to factory spec.

Most BBC's like 34 total, provided you have the proper quench area and octane for your compression. It has to do with the chamber design and the time it takes for the flame front to ignite the fuel. If you advance your timing and gain speed you should still be safe unless something else is going on. As soon as you advance timing and either lose speed or don't gain any, back off. The instant you have pre-ignition or detonation you lose power. You'll find that 90% of BBC's are running 34 degrees or something very close.

Thanks guys, I'm gonna leave it where it is at, but check to make sure I'm getting full advance.

34* total is fine on 454mag. I doubt you will gain more than 1mph though.

A 454 Mag at 8* usually gives you around 32 total. You can swap out the TBoltIV box off of a 6 cylinder and pick up around 3* of total advance, but you can also bump your timing 2* fairly safely.

Assuming the gas you run doesn't allow your motor to ping, you can run 10* BTDC. It will add around 25 rpm to your top end (again, assuming you don't ping).

Listen closely for pinging when the boat is heavily loaded, and the day is hot and so is the motor. If you detect ANY, then back it off again. I'm fairly sure you won't have a problem unless you are running some pretty junky fuel.

MC

How soon (rpm) can a BBC bennifit from full timing of 33-34 degrees if you could program the timing curve? Would 33 degrees @ 3,000 rpm reduce exhaust gas temps ?

My 500hps with upgraded carbs, bigger cams and all new valvtrain are at 37-38 @ 3000 you think thats to much.

36 should be about right.
38 is probably zero additional power, and running unnecessarily closer to the detonation threshold. My guess is that unless you are running a strict diet of 93 octane, you ought to bring it down a couple of degrees. If you feel you have lost rpm, you can always bump it back up.

That's the good thing about a boat. If you leave the trim settings alone and run with "timing setup A" and then "timing setup B" back to back, the one that makes the most power will show up on the tach. (It's best to run slightly less than optimal trim for these "dyno" runs to ensure consistency - unless your boat runs real close to getting an additional chine out of the water on top end in which those cases can exaggerate a performance increase).

MC