The Ford Barn - View Single Post - Adjustable lifters keep backing off

rotorwrench · 05-22-2012, 01:20 PM

Most of the old valve grinding machines have a set up on them to grind the stems. Of course that started to change after the flathead era was pretty well over.

Motorcycles always used a collet type split nut with a tapered seat to lock the adjusters but you were expected to adjust the clearance every 20K miles or so on them. Those threads get tension every time the valve opens in normal operation so it's just a matter of time before the threads loosen up. Heavy valve springs will speed the process up. A collet lock nut would have been better but there is just not enough room for it.

05-22-2012, 01:20 PM	#30
rotorwrench Senior Member Join Date: Jun 2010 Location: San Antonio, Texas Posts: 18,018	Re: Adjustable lifters keep backing off - what do u do? Most of the old valve grinding machines have a set up on them to grind the stems. Of course that started to change after the flathead era was pretty well over. Motorcycles always used a collet type split nut with a tapered seat to lock the adjusters but you were expected to adjust the clearance every 20K miles or so on them. Those threads get tension every time the valve opens in normal operation so it's just a matter of time before the threads loosen up. Heavy valve springs will speed the process up. A collet lock nut would have been better but there is just not enough room for it.