Carb blowing gas back on Z225 A John Deere

[mowermonkey]

Guys, 18 HP Briggs model 31 P 707 blowing gas back thru carb. I have put new camshaft, tappets, and adjusted the valves to .003 and .005.
I pulled the head and lapped valves, seem to be good. Installed new springs and keepers. Nothing seems to help !!!
Any ideas?

 

[Scrubcadet10]

did you line the timing marks up on the crank and cam gears?
Did you install the camshaft to remedy the problem, or did it start after you installed the cam?

 

[mowermonkey]

Yes, I aligned the marks while installing new cam. I put new cam in because I couldn't feel the comp. release bump while turning by hand.

 

[Gumby83]

If you’re still trying to figure this out -

If I’m understanding, there’s gas blowing out of the carb on the air filter side, correct? If so, this is a matter of valve timing. The intake valve is opening at the wrong time and allowing pressure from the exhaust stroke to escape through the intake.

I’m not familiar with the specifics of your engine, but I’ve seen a couple of Briggs engines sheer the gear or flywheel key, so even though the timing marks were lined up, the timing was still off. If you didn’t have a clear view of the crank gear when installing the new cam, verifying the crank gear is clocked correctly would be worthwhile.

 

[Fish]

Was it doing this also before you did all of that work?