Griffon 58 Repairs

The top photo shows the gaping hole left in the crankcase by the flailing rod. This was caused by failure of one of the con-rod bolts, followed by the other, and appears to be just that. At some point in the past the split pins had been removed from the bottom-end of the engine, which is unusual as this assembly is designed to be removed complete and dismantled on the bench. All I was able to do on inspecting the engine originally was to chech the condition of them centre main bearing and see that none of the big end nuts were loose, then fit new split pins, it could well be that the bolts have been over-tightened at some time, so as a precaution we are going to replace them all. Rolls-Royce came up with an interesting graph showing how the loading on these bolts increases above the normal level by running the engines a light throttle openings and high rpm, due to the induction vacuum, so we will be looking at limiting this engine to 2000rpm, and the Merlins perhaps slightly higher. The lower photo is how the engine stands at present, January 2007, while we overhaul the cylinder blocks, two liners and a pair of con-rods and pistonswere written off. The engine was doing 2500 rpm when it broke, at this speed those huge pistons are going up and down the 6.6" stroke over 40 times per second meaning that extensive damage is unavoidable. The big hole in the crankcase has been repaired, using a section from a Meteor crankcase and Robins expertise!