Oki. Do you know how the mpg´s are in cruise/top speed on this rigg?

I never really paid attention. Of course we don't pay as much for gas as you either.

All black Merc motors where rated at crank...EFI gave it 330hp carbed 310hp

98 boat coulda been either way, but guessing it's efi..

They are EFI.

I just want to know about how far I can get ona tank.

Depends if your WOT ir just cruising...I'd say 100 miles you better be looking for gas. I ran mine hard for 90 miles and was sitting on E same fuel tank.

I get around 1.5 mpg cruising easy. Made a 120 mile run last year (one way) running 42 - 45 the whole way and burned almost exactly 80 gallons.

If I remember right Merc used to put both numbers in the owners manual. Carbed 7.4s were never 310hp though. 330 at crank, 300 at prop... I think the efi engines were all rated at the prop. (502 was 415hp, 454mag was 385, etc). Been a while back though so I could be wrong.

not trying to argue for sure, but I've always understood only blue motors where rated at prop..500's 470hp prop etc. 502 415hp at crank 496ho 425hp at crank

Getting a little fuzzy but I think early 90's, everything was rated at the crank but Merc started publishing both numbers. When things switched from carb to efi I THINK they started rating at the prop. Then I guess went back to the crank with the 496 platform? Really up until a couple of years ago I thought my 496 mags were 375hp at the prop. Anyway, some google searches would probably clear it up since Merc definitely wasn't very consistent. I could be wrong, who knows....