Buy a first run out engine and overhaul it. There is seldom a problem with the O-200 cases. If you find a problem when you spec out the case, you can send it off to DIVCO to have it milled and line bored. The last O-320 case I had them do cost me roughly $650 to have welded, milled, line bored and Alodined.
The crank can be turned down to -.010/-.010 and re-nitrided for around $500. A new crank was $3300 last time I checked. A new crank may not fit an old case without some machine work to the nose of the case. At some poitn in time, Continental increased the radius of the shoulder that supports the front thrust bearing on the crank. That radius doesn't quite clear on the old cases, so they require a tiny bit of machine work to clearance the crank in front of the front thrust bearing/oil slinger. That is the same mod that needs to be done to use the O-200 crank in a C-85 case. Buy new cylinders. The older cylinders have an A.D. against them as there were some that failed due to excessive cylinder pressures, so the timing was retarded to lower the cylinder pressures. Especially if you want to run high compression pistons, you want the new cylinders. That also affords you the option of converting your engine to the modern pushrod tubes and pushrod tube seals. In the long run, you'll be glad you did. If you buy the O-200-D cylinders, you'll also get the higher compression O-200-D pistons. I would not use C-85 pistons in my O-200 again. I ran them for 350 hours, then removed them due to some issues I was having with the incorrect fit of the pistons. The worst problem was that the top ring was actually running off the top of the bore in 2 of the 4 cylinders and hitting the aluminum head. That was causing some really strange ring wear on the bottom side of the top ring. If you are really gung ho about high compression pistons, buy a set from LyCon as they will fit the engine properly. Note that the C-85 is not a production engine anymore, so the pistons are somewhat expensive anyway, so you might as well buy the LyCon pistons that fit correctly and are actually a bit higher compression, or the O-200-D pistons. FWIW, I converted mine back to the stock pistons, then built a tuned exhaust system, and got a net gain in performance with the lower compression engine. A good exhaust will get you a lot more than the high compression pistons. There are lots of arguements about the cams. Some guys say the C-90 cam will produce more torque because the C-90 red lines at 2475 RPM. I would still use the stock O-200 cam if you intend to have the engine turn it's rated RPM. I fly mine at or near red line most of the time. The engine is quite happy to turn 2750 or more. You might talk to LyCon to see what they recommend as building high performance engines is their thing. Just keep in mind, high performance eats into reliability and longevity. The only reason for replacing the MS carb with the Ellison is if you plan to fly aerobatic flight with negative Gs. It certainly won't out perform the MS carb, but it is an adequate way to get fuel mixed and into the engine. The cost of overhauling a run out engine back to new spec is significantly less than the cost of building up a "new" engine. Depending on what the engine needs, I would say it will cost roughly 35 - 50% of the cost of building up an engine with all new parts. But by all means, do what you think you want. -Jeff Scott Los Alamos, NM > ----- Original Message ----- > From: Craig Williams > Sent: 12/11/12 04:15 AM > To: K Rnet > Subject: KR> best O-200 option for my KR > > Ok you continental guys out there I need an opinion. > > I am going to build an O-200 with the C85 pistons, ?? cam and Ellison EFS-3. > My question is would you buy a run out O-200 or start with a case and build > the entire engine from scratch. Also what cam would give the best > performance? I suspect cost will be similar but maybe not. > > Craig > www.kr2seafury.com > _______________________________________
