That is not my experience on the gaskets. I checked up to a dozen online sources for parts, including gaskets. I chose the one that had the best prices, seemingly for the same merchandise. I keyed all searches to 287707 0220-01 with date code 9408034A . This is an OHV engine, that's the numbers off it.
From PSEP webpage http://www.psep.biz/store/briggs_and...asket_sets.htm
MODEL 287700-287799 BEFORE CODE DATE 97100600
THIS IS A BRIGGS ORIGINAL EQUIPMENT GASKET SET (INCLUDES OIL SEALS)
I received a set that all gaskets fit except for head gasket, which was an L-head gasket.
I finally found the correct gasket at K&T Parts House, which is #23-11077 on the package. That arrived a couple of days ago. It's the same as 273280s.
I took air cleaner off tonite, suspecting a major problem there. The housing cover was tight, and found that air cleaner element was screwed down tight. Housing attached tightly to carb throat. Dust & debris on outside of element, housing outside of element gray/brown with dirt & dust. Removed element and inside of air filter & housing was clean, not even dusty, just like it should be. So, the problem certainly wasn't the air cleaner element.
On disassembly the cylinder was wet with oil, top end had plenty of oil, air cleaner was fine, but entire bore, all the way around cylinder walls, is nothing but scratches & scoring, like it ran with no oil! Rod was knocking, lots of rattling and engine smoking, using over a quart per 8 hours of oil.
The cause of the problem is Briggs designed this $1,300+ engine with a lame-brain cheapo splash oiling system. Oil pan sump is 9" wide but oil capacity is only 1 quart, meaning oil maybe 1/2" deep in pan at most.
So, everytime I mowed on my hills here which is all I have, the engine is starved for oil, causing extreme scoring on cylinder walls destroying the engine.
A colossal waste of a lot of time, money and effort thaks to a lousy design by Briggs & Stratton. Last one for me!