Re: 1968 mercury 500
Bob,
When you say struggles, are you saying the started turns over slowly?
I have a 1963 500 and the first thing I did was oiled (Seafoam) the pistons via the sparkplug holes and let it soak in for a week. Then replaced the following; Timing belt, impeller, condenser, fuel pump and carburetor gaskets, needle and seats, floats, fuel lines, sparkplugs, and lower gear oil. I also cleaned the points and adjusted them while I had it apart.
When tearing down the carburetors the manual comes in handy for information on clearing the passages.
I don?t know if your model has the grease fittings on the distributor, mine had two, but grease and oil everything.
When you go for startup run the oil mix heavy at first. Put it in the water or on muffs. Don?t put a load on it, don?t rev the engine, just start it and let it run. I did this for an hour and smoked out the entire neighborhood with a 24:1 ratio. Running it rich with a heavy amount of oil warming it slowly gives everything a chance to get lubricated and work out the 6 years of oxidation.
