Originally Posted By: AirgunSavant
Originally Posted By: Linctex
Lawnguy,
PLASTIC CAMSHAFT, you'll quickly understand that the need for high zinc in small air-cooled engines is near zero.
Right on... You must have looked at my 708 Exmark... lol
It was a Briggs 3.5 HP I pulled apart maybe 15 years ago. I was stunned.
Plastic gear, sure..... but plastic LOBES?
I guess the valve spring pressure is so insanely low, probably 10 lbs seat pressure and 20lbs fully open!
Meanwhile, my latest 347 stroker engine (roller cam) with Comp Cams valve springs specifies:
98 lbs @ 1.750" (installed height),
284lbs @ 1.200" (valve fully lifted)