Compression issue after rebuild

E

Emsguy

Member
Help everyone…. Ok, this is going to be lengthy. I have completely rebuilt my Briggs and Stratton model 31C707-0026-G. It all started with a broken piston Rod arm. I figured while I was rebuilding and the engine was old I replaced multiple parts. (Cam shaft, cam shaft timing gear, tappet valves, all gaskets) I just put everything back together, started it up with out the spark plug, turned the ignition key and the flywheel spins freely. Put the spark plug in, tried to turn it over and the fly wheel doesn’t want to turn. There is a lot of resistance. The flywheel just doesn’t want to turn. I did a little research and found that it could be a valve issue. I have a Briggs and Stratton service manual and adjusted the rocker valves to the required specs. Put the valve cover back on, cranked it over and had the same results. I now have back firing out of the carb and exhaust. It’s also very hard to turn over to the point where my starter was smoking, no issues with the battery and the starter is fine. After adjusting the valves, the flywheel will spin much better when I have the throttle cable to the lowest setting. When it’s at max, flywheel barely turns. I am suspecting that something is messed up with the timing in the cam shaft even though I lined the marks up. Does anyone have any suggestions?
 
To verify if compression remove the spark plug.

But I am thinking either an assembly error, wrong rod, or aluminum build up on the crankshaft journal.
 
Ok so oddly enough I tightened the valves a little more than the specs and now it’s turning over with no problem… but now I have no start…
 
StarTech said:
To verify if compression remove the spark plug.

But I am thinking either an assembly error, wrong rod, or aluminum build up on the crankshaft journal.
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I have compression now. I tightened the exhaust valve up a little more than specs… either my feeler gauge is wrong or some other reason. Now i have no start
 
Also, I confirmed that I do have spark. I also sprayed a little carb cleaner into the intake to see if it would start and no luck
 
Ok update on this… I took the whole thing apart and found that I had the cam shaft timing not lined up correctly….. smh…. Got everything back together, tried to adjust the valves again and now I have back firing out of the exhaust when I have the throttle cable at low speed. At this point I’m stumped…. Still won’t start
 
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