9outof10mms
Enginerding, good coffee, and factual opinions.
2A Bourbon Hound 2024
Supporting Member
Multi-Factor Enabled
Word of caution to those who do their own spark plug changes: don’t use those cheap-o 99-cent disc ones that are hanging a the register of every auto part store. Mine was off by a full 0.01”.
I was changing the plugs on the wife’s Jeep today (side note: simply old plugs can cause a hellacious misfire—damn temperamental Jeeps) and checked the gap on my “pre-gapped” Bosch plugs. Using my cheap-o disc thing, I noticed they were off by a good 0.01-0.015”. It wasn’t until the 5th one (of 6 total) that I thought to myself: mayb something else is off—there’s no way brand new plus would all be this bad. So I dug out grandad’s old metal shim gap set. Sure enough, I had now over-gapped my new plugs by a good (you guessed it) 0.01-0.015”.
Never again will I trust a cheap measuring device. Grandad’s old metal shims worked like a champ, and the little wrench tool it comes with is far easier to bend the spark arm in either direction without worrying about busting the electrode. I’m talking the “feeler gauge” style.
I was changing the plugs on the wife’s Jeep today (side note: simply old plugs can cause a hellacious misfire—damn temperamental Jeeps) and checked the gap on my “pre-gapped” Bosch plugs. Using my cheap-o disc thing, I noticed they were off by a good 0.01-0.015”. It wasn’t until the 5th one (of 6 total) that I thought to myself: mayb something else is off—there’s no way brand new plus would all be this bad. So I dug out grandad’s old metal shim gap set. Sure enough, I had now over-gapped my new plugs by a good (you guessed it) 0.01-0.015”.
Never again will I trust a cheap measuring device. Grandad’s old metal shims worked like a champ, and the little wrench tool it comes with is far easier to bend the spark arm in either direction without worrying about busting the electrode. I’m talking the “feeler gauge” style.