Re: Top speed with 18hp Evinrude on 14′ aluminum

[chris-p]

Stephen,

My best advice is take your time, measure, inspect, and play detective.

Start with the bore. It is first within spec? Not out of round? Tapered?

The bore should be 2.496" Opinions on out of round tolerances or wear will vary.

Your piston to cylinder wall gap should be within .0035 to .004. Mic your piston OD, then subtract that from the Bore.

The ring end gap by the book is .007 to .017, however any more than .014 and I re ring for sure.

Once you determine if your block is good (always step #1), move on to your pistons. Measure OD. Inspect side wall for grooves. Inspect wrist pin bore.

Check the rods. MIC the ID of both big end and small end bores. Inspect for damage or grooves, or signs of overheating.

Needle bearing re use will get varying opinions. If they are bluing, absolutely toss em. Inspect them with a magnifying glass. When I do a rebuild, to be honest I install new. I figure if they got through 75 or so years, they have done their job.

Crank bearings are another tricky one to "test". Again, if I am going through trouble of a full rebuild, I install new bearings on the crank.

Check the crank halves, ensure they are true. Clean up spotless. Obviously install a new spaghetti seal. Use the proper primer and anaerobic sealer. Silly to go through all this, and pump silicone into it. Don’t laugh, seen it done. Install new gaskets, and ensure gasket surfaces are clean and true. Change ALL the seals.

Then, when complete, ensure you properly break it in. We can help with that. When you are done, if done properly, will last another 100 years, for your kids, and your kids-kids, to enjoy.

As you can imagine, doing it right is definitely NOT cheap. Yet rewarding.