RCinNC
Well-Known Member
Thanks Reno. I knew that's a general rule of thumb, but there are enough factors at play with lubricated threads that I'd hate to generalize. I just dropped in on the Engineering Toolbox website, and the table of values I saw on the site show that torque reduction can vary quite a bit based on what the lubricant is. For something like SAE 40 motor oil the torque values are reduced by 30-40%, but for a graphite lubricant the values are reduced by 50-55%. That's a pretty big jump between the low end of the motor oil and the high end of graphite, and I have no idea where anti-seize would fall in that range, or even if aluminum anti-seize would be the same as copper.
When it comes to threads in an aluminum head, I get kind of paranoid because the penalty for failure can be kind of high.
It's a moot point though if the spark plugs are tightened based on instructions like "tighten by hand until the gasket seats, then tighten an additional 1/4 turn". I think that's how it was when I changed the spark plugs on my girlfriend's CR-V.
When it comes to threads in an aluminum head, I get kind of paranoid because the penalty for failure can be kind of high.
It's a moot point though if the spark plugs are tightened based on instructions like "tighten by hand until the gasket seats, then tighten an additional 1/4 turn". I think that's how it was when I changed the spark plugs on my girlfriend's CR-V.
