fuel economy older engine

[gazza2006au]

and idea how much fuel a 71 50hp evinrude will use?

[FNQCairns]

A fair bit relatively speaking today, they where thirsty and HP was rated at the flywheel so it will output nearer 40hp relative again to today.

Fuel use will depend on what you use it for, short bay trips from the ramp chasing whiting/flathead etc then a days fuel can be negligible, range wider and a modern 4 stroke 50 will use a noticeable amount less somewhere like half.

Going out on a limb say 15L/h as sensible most at fast cruise, still if on tinny it will be less than on a glass boat, proping, people on board, length, hull design...so many variables.

[finga]

Not much if it was in my shed with the rest of the old motors.
They only get a dry run every now again.
But on a normal boat the usage will vary greatly as mentioned by FNQC dude.

And it would be gutless compared to a 50HP made this century or the last 2 decades of the last century.