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I don't recall off hand what engine I had on a lincoln 225. The generator end of the cam has a set of centrifical counter weights that control the spark advance. There is two small pins that hold these weights on the cam shaft. One sheared at the cam and allowed the weights to grind into the block and snapping the shaft. Best I can remember is there are bearings for the cam in the block. Subsequent damage....good question. You'll have to look around in there and check everything. There is no timing chain, helical gears drive the cam from the crank and also the oil pump (flywheel end). The flywheel is on a keyed tapered shaft and can be very difficult to remove. The flywheel is cast iron and usually very brittle and easy to break. You need to take great care in removing this. Soak for a long time with penetrating oil after removing the retaining bolt. I took a couple pieces of bar stock and placed them behind the flywheel on the hub then tack welded them together on the exposed ends with a couple more short pieces (home made bearing puller plate in large size). Use a big two jaw puller to put medium pressure on the bar stock (pulling on the hub of the flywheel). Then use sharp but light blows on the puller bolt and be prepared to catch the flywheel. It's heavy and will usually come off with quite some force behind it. You don't want to break it because they are well over $500 for a new one. Once off, you will have access to the timing cover. You have to compress the valve springs to allow the cam followers to slide away from the cam and the cam will then slide out. Now you can inspect the internal of the block for damage. You may also wish to remove the lower portion of the block to clean the oil pan out and check for damage on the crank. The generator can attach to the crank in a couple ways depending on the mfg. It's either a direct shaft connection with a splined or keyed shaft coupler. The other is a plate connection. One plate on the crank and one plate of the shaft of the gen held together with 4 or 6 bolts. I'll tell you right up front that parts for the Onan are very expensive. Often times you pay more for the parts to rebuild an old engine like this as you will buying a whole new welding machine. Good luck!
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