Re: 1974 Evinrude 70 h.p. motor
I ran a 1976 Johnson 70 HP for a few years on a 15' fiberglass tri-hull. The motor was very easy to work on. 1974 will put you past the hydroelectric shift era for Johnson/Evinrude, so you should be good to go there. The shift Shaft screw is not any more difficult than other configurations. Its located in an odd position between the carburetor and starter. If I recall correctly, the easy way to get it off was to remove the air box. 6 extra screws need to come out. The problems I had with the motor were mostly electrical/spark related; the rectifier was not functional when I got the motor, and the power pack went at the end of the first season. Luckily enough there are very well-defined troubleshooting procedures for the CDI ignitions, and parts are readily available (although as a previous poster mentioned, some can be a bit on the pricy side). The 1976 model years had a unique problem with mid-range acceleration, but it was supposedly limited to the 1976 models only. Be very careful about replacement parts; some of the parts are interchangeable with similar motors up to the mid-80's some are very unique to the 1973-1978 models. I believe in 1978 there was a change in the lower units, and that is where I started to find a lot of incompatibilities. As to fuel, I would run that boat 4-6 hours at a time at high cruising speed/WOT (pulling tubes for the kids or running from fishing spot to fishing spot all day long) on 6 gallons of gas. I would estimate it would burn through about a gallon an hour if run right around 5K RPM.
I would be more concerned with a 1974 fiberglass boat. Make absolutely sure you are not looking at a fiberglass shell around a rotted wood core. Check the transom for any flex, check around the seats and at the base of any livewells or storage boxes. $2500 is too much to pay for a 1974 motor, a trailer, and a restoration project hull.
Good luck.
Rgds
Eric
