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Joe K · 10-14-2019, 02:27 PM

My rebuilder recommended the single nut.

My first opinion was double nut - but never having any experience with either I asked him why for his preference.

"The double nut version relies on the frictional 'jamb' between the two nuts which we take as locknut. However, the friction is entirely lost once the first nut is loose - and the second nut free to turn by vibration. It's an 'all or nothing' lock.

Meanwhile, the single nut version relies on "prevailing torque," usually, but not always the the result of a plastic insert. That prevailing torque does not release suddenly like a single nut but requires a force larger than the torque necessary to set it to remove it."

Plus he says "The single nut version are easier, are adjusted faster, two wrenches instead of three, and more consistent in setting - just the action of setting the second nut on the two nut version can be enough to change the gap requiring re-doing it again."

I took him at his expertise - and have not had a regret. This included complete disassembly of the engine later for repainting - and a re-assembly using the marked & matched parts.

Joe K

10-14-2019, 02:27 PM	#2
Joe K Senior Member Join Date: Jul 2010 Location: Cow Hampshire Posts: 4,188	Re: adjustable tappets My rebuilder recommended the single nut. My first opinion was double nut - but never having any experience with either I asked him why for his preference. "The double nut version relies on the frictional 'jamb' between the two nuts which we take as locknut. However, the friction is entirely lost once the first nut is loose - and the second nut free to turn by vibration. It's an 'all or nothing' lock. Meanwhile, the single nut version relies on "prevailing torque," usually, but not always the the result of a plastic insert. That prevailing torque does not release suddenly like a single nut but requires a force larger than the torque necessary to set it to remove it." Plus he says "The single nut version are easier, are adjusted faster, two wrenches instead of three, and more consistent in setting - just the action of setting the second nut on the two nut version can be enough to change the gap requiring re-doing it again." I took him at his expertise - and have not had a regret. This included complete disassembly of the engine later for repainting - and a re-assembly using the marked & matched parts. Joe K __________________ Shudda kept the horse.