Installing 2000 Mazda Miata spark plugs

I have a question about installing spark plugs with a metal gasket. I’ve noticed that after installing the plugs to the specified torque if I go back and check, they will require more tightening to get the specified torque. So, do I torque then once on installation or go back and re-torque them after installation?

I would re-torque them. The gasket is taking a “set” and losing torque. I’ve not experienced that on gasketed plugs but I don’t usually check them after installation. Be sure you aren’t over torquing.

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I agree with you about re-torqueing. I suspect the gasket “relaxes” after the initial tightening. Thanks for you input.

I would not re-torque them, those are crush gaskets and by re-torquing them you are just further crushing the gasket.
I will admit I never use a torque wrench on spark plugs. In more than 60 years of doing it I have never had one come out and never stripped one.
As a teenager working at a gas station we used to remove, clean, re-gap and reinstall them for 25 cents each. Back then plugs were cleaned at 5000 miles and replaced at 10,000 along with points and condenser.


Maybe do check them once after you torque them the first time, but other than that one check, I’d leave them alone. Over tightening spark plugs is an easy way to damage them and the head.

Everything is designed to work properly with just the initial torque setting. Things that are designed for multi-step torquing (e.g. torque to yield head bolts) clearly spell out the specific requirements and take into account the additional break away torque from an already partially tightened fastener. You’re risking damaging both plug and head by second guessing the experts that designed it.

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Thanks all for your inputs. I think I will play it safe and torque them once on installation. Thanks again. Ron