starter dragging (valves have been adjusted)

[tley]

20 hp briggs intec gold (31c707)
Today I went to move it after it has been sitting for about two months and would not start (starter dragging). Having these symptoms several times before, I knew the valves needed adjustment. That did not work, maybe a dead battery? Nope, 12 volts at the battery. Bad battery? Maybe voltage dropped to 2 volts when starting. Replaced the battery today, no change in problem. Through all of this I have checked and rechecked the valves several times. Starter spins freely with spark plug removed. Spark plug does have spark. It ran fine when i parked it 2 months ago, although I can not remember if starter had started dragging or not. I read elsewhere that there is supposed to be a "decompression bump" in the valve train? I am not sure what I am looking for here, is there any video demonstrating this? I fear that I may have a cam that has gone flat...
Thanks for any input

 

[7394]

Briggs uses a bump on the cam lobe so it can bleed off compression at engine cranking speed. Making it turn easier.

Setting the valves requires finding TDC, then turn CW an additional 1/4 INCH, & then adjust valves. That was how my 20 HP Briggs Intek was.

 

[Rivets]

Check the oil level to make sure the crankcase is not full of fuel. Pull the spark plug and try the starter. Does it spin easily with no plug?

 

[tley]

Thanks. I am fairly sure the valves are correctly adjusted as i have done this a few times. The more research i do the more its looking like a bad cam.

 

[tley]

Motor turns easily with spark plug removed

 

[d_sharier]

In regards to the 31XXXX Briggs, I have seen 3 this season that have suffered a cam shaft failure that involves the compression release. The compression release had come completely off of the camshaft. Briggs has changed the part number to a newer camshaft. I believe they extended the manufacturers warranty to cover the cost of the part only for another year. So they know these are showing to be a problem. If you have ruled out all of the other possible issues, electrical, other timing, and valve adjustments, I would be willing to bet you may fall into this category. With the engine off, spark plug in the engine, can you spin with engine over, by hand, without having to struggle through the complete cycle?

 

[SeniorCitizen]

Check cam relief bump condition with your feeler gauge. Think about that for a minute and if the bell doesn't ring check back.

 

[possum]

Just in case you did not. See how much if any fuel has gotten into the crankcase.

 

[tley]

Yes the motor is very hard to turn by hand past the compression stroke. The valves seem to only open and close in their normal fashion, i do not observe an additional opening to relieve compression. Pretty sure my compression release has failed.
As far as parts go, looks like a case gasket and the cam/lifters is about all i would need for cam replacement?

 

[SeniorCitizen]

Zing, the bell didn't ring.