Re: online service manual for briggs model 28n707?
Reminds me of the arguments we used to have on the kart racing forums over valve lash, one side said that there was a performance increase from lift by running 0.0005", versus those that ran a more conservative and safe 0.002". Effectively there was a net lift increase of 0.0015"...however, the end result was that in multiple back to back dyno runs, there was more HP increase from wrapping the header vs not wrapping the header, than valve lash, which had no discernable effect on power/performance.
In this situation, the question is, is there a benefit from using 2 different feeler gauges, and having to explain which rocker is intake and which is exhaust, for .002" less clearance, vs streamlining the process by using one feeler gauge and being within the recommended lash range on both valves...
Personally, in testing, Ive set both valve as close as 0.002" and had no ill effects on running/longevity, no valve burning, and it starts normally...but briggs says no closer than .005 on exhaust or .003" intake... Ive also had engines that started absolutely fine, but you could hear the rockers clacking, and I find .010 or more lash...and it starts perfectly.
My experience tells me that, valve train wear is a crapshoot on briggs OHV engines. Ive got engines out there with more than 300 hours on them, never had the valve covers off, without problems. And Ive had tractors come in with under 60 hours on them, with more than 0,020" lash,....
Ive got customers that I have to relash the engines every 2 years, they arent slipping, they just wont crank when it gets over like 0.010" lash, yet others will crank with .015" or more.
1993 Wheel Horse 416-H
1997 K3500 Dually Sierra
Crew Cab, Long bed, Vortec 454
1995 K3500 Silverado
1995 K2500 Silverado
6.5 Detroit Turbo Diesel
1994 GMC Sierra Z71