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Briggs and Stratton Valve timing degees

#1

E

earl6969

My engine is a 31C707 0154E1 050228ZA. I have the camshaft out and am trying to determine if the cam lobes have slipped on the splines causing the valve timing to be off. Does anybody know at what point(in degrees) each valve is supposed to open.


#2

M

motoman

earl, Don't know what that engine is but would expect a cam to be indexed to a splined shaft with some sort of ref. mark. If the splines are apart can't you examine for damage or twist?


#3

pugaltitude

pugaltitude

Both the cam shaft and crank gear have a dot which you use to line up.
They should be very visible.
Slot into position.


#4

E

earl6969

Both alignment marks are together. I was told by my parts store guy that the lobes can slip around the splines they are pressed onto, causing mistiming. My old one has no obvious defects visible to the naked eye. He sold me a new camshaft. Compression is releasing now during starter spin(like it's supposed to), but it will not start. It backfires every few turns now instead of backfiring more often. I initially set it .003 int. and .005 exhaust but it just backfired really loud. Through trial and error (making small adjustments) it backfires less often and quieter, but still won't start.
I'm stumped now.


#5

E

earl6969

earl6969 said:
Both alignment marks are together. I was told by my parts store guy that the lobes can slip around the splines they are pressed onto, causing mistiming. My old one has no obvious defects visible to the naked eye. He sold me a new camshaft. Compression is releasing now during starter spin(like it's supposed to), but it will not start. It backfires every few turns now instead of backfiring more often. I initially set it .003 int. and .005 exhaust but it just backfired really loud. Through trial and error (making small adjustments) it backfires less often and quieter, but still won't start.
I'm stumped now.
Click to expand...

I'm gonna check the flywheel key.....................


#6

pugaltitude

pugaltitude

It could be the flywheel key but back firing and not starting could be a symptom of a blown head gasket.


#7

Fish

Fish

Those cams with the splines were bad for wearing off lobes, but I have never seen one spin.

I would pull the valve cover off and watch the valve movements closely, turning the engine over by hand. Sounds like a loose valve seat or a sticking valve.


#8

M

motoman

Look for a pushed guide


#9

E

earl6969

It was the flywheel key. I cannot believe I let that one get me again !!! LOL


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