Well I am almost ready for my boat to go in the water after I hauled the engine pulled off the transom and had the steering shaft and upper shaft replaced. My question what octane fuel should I run in my 350 mag? T he boat is a formula 206 ls all I have left to do is put on a lower shift cable and put on the outdrive!!! So this should happen the next couple of days!!!
Thanks AGAIN

You can run any grade with a 350 Mag. I usually ran 89 because that was what was available at the gas dock when I had a 350. Not a high compression motor that you will have problems with if you run 87 etc...

Not sure how long the boat has been out of the water but if it has been some time you may want to put some High test in there to get the octane level back up. However once you get that old gas out you can put the cheap stuff in there no problem.

Jon

I run regular or mid grade fuels.
Try adding a fuel system cleaner to the first tank and then add stabilizer to each tank there after. I do that so I don't have to worry about gunk forming in the tank and carb.
Don't forget to change the fuel filters a couple of times this season. It may load up with junk for the tank. Check the carb filter too, most people forget it's there. Mine was removed a long time ago.

I just pulled out the original Mercury Operation And Maintenance Manual, dated 1987, and it recommends 89 or higher octane fuels.

Like I said before if you need any info I have all the original manuals, schematics and brochures for the 206.
Just ask.