Answers
Intermittently after it rains, my check eng light comes on and when I accelerate my car shakes and stutters. Since it happens after it rains, I think it is my spark plug wire harness. Since I am replacing the wiring, I am going to replace the spark plugs as well. I need to know what the gap is though.
The gap is .043 but most sparkplugs gaps are already preset .
This video explains spark plug metalurgy and the trend towards precious metal electrodes
I replaced my spark plugs with some Autolite Double Platinum spark plugs, but now it shakes and hesitates to accelerate, my manual says to set the gap at .043 or (1.1) and also my service engine light turned on. Should i reduce the gap? or what should i do for my car to stop shaking and hesitating to accelerate. Its a 2004 Nissan Altima 2.5SL 4-Cyl
go to autozone, pepboys, or wherever u buy ur car parts. ask for ngk spark plugs. u will have three choices. the cheapest and NGK V-Power, NGK platinum, and NGK iridium. i would recommend ngk v-power if u have no problem doing the plugs again at 30k miles. theyre also the cheapest spark plugs and deliver a good spark. platinums will double the life but cost more than twice as much as the v-power plugs. Iridiums i would only get if the vehicle is highly modified. Goodluck !...PS....They all come properly gapped so dont touch em.
go to autolite website thsy list them all
I own a 1983 Yamaha Virago 500cc, and I run Autolite 4263 plugs. I need new plug wires, but I'm not sure of the size. I've seen online 8mm or 6mm, and I'd hate to buy the wrong size. Anyone know what size I need?
7 mm
4143 is hotter.
Going "up" to heaven is cool
Going "down" to hell is hot
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Pre-WWI Spark Plug Charts? - AACA Forums
I heard a story once that at least some of the early Metz cars used an extra long spark plug... I have a couple and they fit a hit and miss engine I have... One useful test would be to measure the spark plug hole from the edge of the opening to the piston chamber... If my information us correct the distance will exceed 2".. If this is correct other plugs will fit in the hole but the spark will occur so far from the chamber that ignition will be less effective.. as for books and references good luck.. I have a few that covered off major car brands but unusual brands like Metz... I have never found... tractor references are also very hard to find . My earliest car sparkplug catalogue is 1932.....
1966 Autolite Spark Plug Ad
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Autolite program aims to break spark-plug misconceptionsSearch-Autoparts.com - Nov 05, 2009
The promotion, set to run for six months, gives do-it-yourselfers the opportunity to put Autolite spark plugs to the test. Consumers that purchase a set of
Autolite Spark Plug Platinum Tapered Seat 14mm Thread .460" Reach Projected Tip
Autolite Double Platinum Spark Plug AP3923
Autolite 86048 Premium Silicone Spark Plug Wires
LOT OF 24 SPARK PLUGS. AUTOLITE, BOSCH NOS 
Ford Racing Performance Autolite spark plug information