Briggs 15 HP wont start

[mikey55]

I have a craftsman rider with a 15 HP Briggs 28N707. I replaced the connecting rod and reassembled and it wont start. The connecting rod melted onto the crankshaft but the crankshaft was OK and all else was fine. piston was fine and cylinder was OK. rings were OK. I gets spark. It gets gas. It backfires when I crank it. When I turn the flywheel by hand I hear hissing from the cylinder like air escaping? I set the timing gear and cam gear exactly with both markers aligned. Is there another way to set the timing markers? Do I need to position the piston in a particular location before aligning markers? I just aligned the markers and set the valves? Please let me know if you have good ideas.

[John W]

You probably have the marks aligned 180 degrees out.

If correct, with the cam gear timing mark and the crank gear timing mark aligned, both valves are closed. If the marks are aligned and a valve is open, you need to remove the camshaft and rotate it 180 degrees.

Have a look here for the procedure to degree a camshaft:

John W

[DR, Bob]

FYI if your exactly 180 degrees out rotate the crankshaft 1 full turn and your marks will line up ( cam makes 1 rotation for crankshaft 2 rotations. so every other rotation of the timing marks show 180 degrees out) Did you have the head off? if so did you reuse old gasket? if so the gasket is shot and leaking? do you have any comprestion? are you sure you got the timing marks right? that is my first thoughts you could be out a couple teeth I would start there.

"John W"

[mikey55]

[Tony Kimmell]

I don't understand what they are saying either... because the cam on a single cylinder engine CAN'T be 180 out. If it was, then the timing marks would be on opposite sides of one another! As long as the marks are aligned, it's in time.