tecumseh vibration

Hi all,

Bought my early 70s 10xl for a daily mower. Also would like to add other implements. Previous owner (not that he was particularly forthcoming about some of the problems) told me that the engine had been replaced with a rare off-the-shelf replacement three years prior--all flashings and guards in place. Got the thing running and there is a LOT of vibration at full RPM. Previously owned an AC Big 10, so I feel like I know what kind of vibration to expect, but this is insane. Web research suggest that Tecumseh's are bad where vibration is concerned. On the other hand, a guy I know suggested that there is a way somewhere in the bottom half of the motor to properly balance the engine.

Question is, do I try to fix this issue or give up and try to find another motor? If another motor, what kind of luck am I going to have with a newer engine from a different manufacturer?

Thanks for any thoughts.

As an engineer working for a foundry that supplied Tecumseh, Briggs, and OMC crankshafts for years, I can say that Tecumsehs are no more prone to excessive vibration than any other manufacturer's engines. It sounds like that "off the shelf" engine has been rebuilt with non-standard parts affecting the balance or it was intended for an application which had an external baling arrangement.

Thanks for your reply! So you are saying there is no way to eliminate the vibration short of rebuilding the engine? What would you do if you were me?

Thanks again.

Oops, i meant balancing.

Some engines have extra balance weights in the crankcase, gear driven off the crankshaft to cancel the normal out-of-balance condition 90 degrees to the cylinder axis. If the engine has been apart, these weights may not be timed right and that can really screw up the balance big time.

What's really sad is that the thing idles like a dream, very low rpms, very sweet. If I could run it at half speed, that would be ideal. One thing I did notice is that it is much nicer at 3/4--is it possible that it is over-revving when I throttle it up to 1/1? I imagine that would cause a lot of vibration.

Maybe if I can find a reel-type tow mower. My dad uses a big gang mower to mow his field. Seems to work well, but I haven't seen one for lawn use other than the push type.