> Take the top cowl off and the ID plate on the engine will be > visible. Mine > states clearly that it is a C-90. If it doesn't have an ID > plate I would be > wary!
According to the FAA, if it doesn't have a data plate, it isn't an engine. On the other hand, old Continental data plates were painted with most everything except the dash number and the serial number. So there are a lot of legal data plates that look like someone just punched a bunch of numbers on a scrap of aluminum. You can't necessarily tell a C-90-12F from a C-85-12F unless you know which serial numbers were which. Another way to tell for sure is pull a plug out and measure the stroke. The C-90 has a longer stroke than the 85. (I don't have the numbers off the top of my head). Or look at the prop. If it's got a 52 inch pitch (metal prop) and it makes more than 2050 RPM static, It's performing like a C-90.
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