Quote:
Originally Posted by canstanza2007
Thank you for the info, Schurkey, a few more questions, the replacement engine is supposed to have 56,000 miles on it, what should the compression be, what other things should I check before buying this engine? (Oil pressure ???) Also can I swap over the carburetor, is one better than the other?
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Mileage is less important than proper oil changes. Nobody seems to have done frequent oil changes.
Cranking compression will vary with cranking speed, altitude, and other factors. I like to see about 150 psi, but I probably wouldn't get that in Denver. As always, evenness among cylinders tells more than absolute numbers.
Oil pressure: higher is better within reason--and using proper oil. Jacking-up the oil pressure by using heavy oil is cheating. The most-telling condition is fully warmed-up, in gear. Under 10 psi is trouble, 10 to 20 psi is pretty normal. Back when those engines were new, 10W-40 oil was very common. Today, 10W-30 or 5W-30 would be more usual.
If I were buying a used engine, I'd do a cylinder balance test with a vacuum gauge connected to manifold vacuum. It's simple, quick, requires a minimum of tools, and provides useful information. A 12-volt test light and a vacuum gauge is all that's needed. Connect the vacuum gauge to manifold vacuum. Warm-up the engine, then slide the test light probe between the wire and the distributor cap boot. A bit of dielectric grease on the test light probe helps to slide the probe. Do NOT damage or pierce the plug wire. The test light will short out the cylinder when the spark is able to ground through the test light (the light will not glow.) Watch for even vacuum drop as each cylinder is shorted-out in turn. If you short a cylinder and the vacuum doesn't drop, that cylinder is weak or dead. If possible, short the two groups of "every other" cylinders. So if you can, short-out 1, 4, 6, 7 and 8, 3, 5, 2. This tests the carb idle mixture adjustment.