Small Engines (Lawn Mowers, etc.): replace engine?, head bolts, heli coil

Question
thanks for the previous answer michael,

I have an old tecumseh 4 hp, 4 cycle engine on a AMF two stage snowblower.  It hasn't run in years so I started by having a professional acid bath and rebuild the carb with a rebuid kit.  I put in a new sparkplug and since have kept it clean.  I disposed of the fuel and added new.   I replaced the condenser and points.  After all of that, it idles really rough (the screw adjustments have been double and triple checked-they are accurate) sometimes backfiring little but the best way to describe it is spitting and coughing (it takes many pulls to keep it going but after a warm up it sits on its own running roughly).  I checked many of your previous questions before I sent this and tightened the head bolts, however it seems that some of the threads and bolts had been stripped (including in the head)and when I tried to tighten down on two of them they obviously are stripped out.  Now I notice oil running up and out from under these bolts and I cannot get this thing to get any more throttle beyond idle--it just sputters out, backfires, and dies if I increase the throttle. Sounds like I have lost compression in the head somewhere or someone tapped a new hole and broke the cylinder wall...Is it time for a new engine?

thanks,
Ryan

Answer
Hi Ryan,

You may be able to add a Heli-Coil type insert to be able to add bolts and properly fasted the head.  The condition you describe now, is not good and probably the cause of the poor running.  You could test the compression, to confirm.
A new engine may be the easiest and best value.

Keep me posted,
Michael