Re: 1988 175 evinrude compression higher on one side of the engine than the other.
You seem to have two port heads on your engine, from reading your thread. (not possible) If the engine is a true 88 175, it is a big bore block. 160 cubes. Due to the way the crossflows were made at the factory, it is not unusual for compression to vary a little between heads. 5-8 lbs variance is not unusual. Personally, I'd prefer the compression between heads to be generally equal over the life of the powerhead. Your variance is outside of that norm, so you have something to check. Make sure both heads are matched. Typically OMC created head part numbers that were sequential. Your 88 175 engine should have these heads on it: 332137 starboard, 332136 port. Those part numbers are cast into the head. It is possible someone changed one head to a non-stock one and that could account for the variance. My guess is that the low head readings are more normal for the stock heads. A high compression big bore head (325638/639) would produce the higher readings you see. Perhaps one of the heads was damaged at some point and replaced. I don't think OMC ever made special low compression head gaskets for that big bore, but if they did-that could explain some of the variance. Perhaps that engine is really a 175 small bore from an earlier model year? What is the model number of the engine?
