Briggs won't hold valve clearance

Check the rocker arm studs. They may have broken loose and are backing out. If loose remove, clean of all oil, apply blue Loctite, reinstall, and torque to 150 in-lbs.
 
The Rocker Ball Set Screw or Nut is torque to 45 in-lbs.

Scott
Thanks for the response.  By the way, I'm performing the method of setting valve-lash by rotating the crankshaft CCW to TDC of compression stroke, inserting a rod in the plug hole, continuing CCW crank rotation until piston lowers apprx 1/4", then setting the valve lashes.  My ref for this is the B&S-published repair manual (online), and I'm defining CCW as viewed from looking down on the top of the engine.  Am I correct in these procedures?  

Hmmm I always did the CW rotation per Service bulletin ASPI 28. Into the power stroke and not into the compression stroke.
 
https://drive.google.com/...pKUJnh7ek5rNEMzb2tHc2s

As long as I been servicing these Briggs engines [10 years now] I didn't see the reference in the service manual until you pointed it out.
 
I actually use a difference method anyway which is a very old method. What Briggs has is a newer method but prefer the old method as I am set in my ways being nearly 60 now.

Sorry for the late resonance I tend to fall off to sleep when I sit down and relax after putting in 10-12 hrs in the shop. I burn my dinner the other night that I had in the oven because I didn't wake up until 4 in the morning. At least I only had the oven at 250 but the chicken was still charcoal.
 
Yes it is the setting of the valves by doing one valve at a time on these singles and twins. Takes longer but at least don't need to measure the piston position beside I got careless when learning to Briggs way and had to pull the head to retrieve the broken dowel once. When it came to V8s you can do half one time and then the other half but I don't see solid lifters anymore except on old engines and a few racing engines.
 
As for the ACR [compression release] bump it occurs on the intake for the 793880 camshaft. As you look at the engine this is the lower valve with the aluminum push rod. Much less raw fuel is wasted as it gets reused and not just not discharge with exhaust. Either way the ACR bump only occurs at start up. There are guys that insist it is always the intake but it depends on which engine you are working on as it can be the exhaust on some models.
 
With the ACR being fragile on these camshafts you do need make sure the bumping occurs. It shouldn't hurt it by turning CCW as it just swing the ACR arm out but it doesn't make sense to me to turn the engine backward of its normal running directions. Now I do see enough of these 310000 series engine where they have broken ACR causing hard starting that I stock a camshaft kit and crankcase gasket at all times.
 
Must be an inherit thing for the 310000 as the 280000 and 330000 uses the same camshaft without problems so far on my end. Just like the head gasket design used on these engine tends to fail a lot too but this follows this design to other models using it. I have several engines destroyed because of this as they burn a lot oil without smoking.