Originally posted by Paul Moir:
Welcome to Iboats, LDS HP!
Here's a little additional information on the FD-11:
Displacement: 22.0 CI
WOT RPMS: 4000-5000, 18hp @ 4500RPM
Spark plugs: Champion J4C (replacing J4J) gapped at .030"
Fuel/Oil mix: 24:1 87 octane gas and TC-W3 outboard oil.
Lower unit oil: BRP (replacing OMC) "HiVis" or equivalent 90 weight outboard gearcase lube.
Parts are still widely available and as far as outboard parts
go, relatively inexpensive. The engine is extremely easy to work on with only a couple "special tools". The most important of those is the service manual
Outboard motors are happiest when they can be run full throttle (at the very least occasionally). They must have the proper propeller attached so they can reach their WOT (full throttle) RPM range. I'm pretty sure your engine would be propped correctly for your boat, but could you describe the boat a bit more? How heavy, what style of boat, what material is it made of? Can you find any numbers on the prop you have?
The 22.0 CID engine saw long service for OMC and was a very popular engine. They even saw race duty (although heavily modified). I think they discontinued it in the 70s as a 25hp, when the new 25/35hp engine came out. Outboards generally, and from this era specifically, seem to have extraordanary life spans. It's far rarer to find one that has worn out than one that has been abused to death.