AlbertBallVC Posted October 8, 2015 Share Posted October 8, 2015 I am rebuilding an OPS.21 engine to aircraft spec, it was originally a car version back in 198? The crankcase, bearings and crankshaft are unused original OPS parts. I ordered some new parts to complete the rebuild but the tolerances aren't as good now as the original parts (I had to machine the backplate to allow the crankshaft to freely spin). I would like some advice on how to install the very fiddly wrist pin wire cir clips that are quite large and the other question relates to the wrist pin, it has a blind hole drilled through it, should the blind end face the front or the rear of the engine? Any advice would be much appreciated. Quote Link to comment Share on other sites More sharing options...
Steve Hargreaves - Moderator Posted October 10, 2015 Share Posted October 10, 2015 I'm not familiar with the engine but often the reason for a blind hole in a gudgeon pin is to prevent a path between opposing ports being created as the piston passes them.....if this is the reason then it doesn't matter which end goes where..... Fitting the wire circlips is an absolute pain...the only tip I can offer is to keep calm & keep trying. Also try doing it in a large clear plastic bag so that at least when the things spring away from their intended position the bag will catch them. Do make absolutely sure they are fully home & seated correctly before running the engine.....a loose circlip will usually spring out at the worst moment (ie max rpm) & wreck the engine.... Good luck!! Quote Link to comment Share on other sites More sharing options...
ROY DAVIES 1 Posted October 10, 2015 Share Posted October 10, 2015 Fitting circlips. Obtain a piece of brass tube 2" or so long that will fit the gudgeon pin hole (just) Fit a circlip Squarely in to it and using a squared off pin or a drill shank that fits the tube (just) push the tube up against the gudgeon in the piston of course and push the circlip home, check it has entered the groove and your done. Quote Link to comment Share on other sites More sharing options...
AlbertBallVC Posted October 10, 2015 Author Share Posted October 10, 2015 Many thanks for the advice fellas. Finally got the circlips in using the plastic bag as suggested to capture the flying circlips. The engine has now been rebuilt. Thanks again for the responses, it's much appreciated. Quote Link to comment Share on other sites More sharing options...
Keith Berriman Posted October 10, 2015 Share Posted October 10, 2015 I am not sure and may well be overruled but if my memory serves me right your OPS engine may rev at nearly 42000 RPM at full throttle were as an aircraft engine revs around 22000 RPM . I assume your revamp drops the revs down as I am not sure if an aircraft prop can take the revs Quote Link to comment Share on other sites More sharing options...
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