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C85 stroker or O200 Installation

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JimC

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I assume you are talking about on a J3.
There are 3 ways to go.

1) Install an O200 crank and pistons in a C85. There are two STC's available to do this. The engine remains a C85 and can then be installed on the J3 by logbook entry per J3 Type Certificate A-691. Note that the stroked C85 has less valve lift than an O200 and will not turn up as high or put out as much power as the O200 (but, it still does quite well).

2) Install an O200 by 337, with a previously approved 337 as supporting data. This requires using a McCauley 7142 prop (which is just about a perfect match for the O200 on a J3), and it does not require the addition of wing tanks or supplemental fuel. You placard the instrument panel with a Maximum RPM limitation of 2640 rpm, which is what the engine wants to turn during climb anyway, when you use the 7142 prop. This is by far the cheapest way to go, and will give the best performance because it does not substantially change the weight of the aircraft.

3) Install an O200 by STC. This requires limiting the fuel in the nose tank and requires the addition of a wing tank, which is a lot of work if the wings are already covered.

The O200 Type Certificate is E-252, but you won't need it.

All the best,
JimC
 

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