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2020 Corvette of the Year Finalist (performance mods)
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The longer plug above the threads means its a colder plug I believe. the part to worry about is the theaded part that projects iinto the cylinders. IF that part is the same then you dont have a clearance issue to worry about internally. Now a colder plug versus a hotter plug is another can of worms that will get really confusing fast with a lot of engineer types throwing all sorts of info at you here. If you have stock iron heads look at the original plug heat range index. If you have aluminum heads, find out what the manufaturer designed them to use with what compression. My aluminum heads manufacturer wanted a specific NGK plug.
Now externally for the length, are you running any of the external shielding or headers? Usually with headers there can be a clearance issue
Last edited by Rescue Rogers; Jun 29, 2019 at 07:27 AM.
The longer plug above the threads means its a colder plug I believe. the part to worry about is the theaded part that projects iinto the cylinders. IF that part is the same then you dont have a clearance issue to worry about internally. Now a colder plug versus a hotter plug is another can of worms that will get really confusing fast with a lot of engineer types throwing all sorts of info at you here. If you have stock iron heads look at the original plug heat range index. If you have aluminum heads, find out what the manufaturer designed them to use with what compression. My aluminum heads manufacturer wanted a specific NGK plug.
Now externally for the length, are you running any of the external shielding or headers? Usually with headers there can be a clearance issue
Thanks..the part that is weird is it is identical numbers r45ts..no headers bone stock L82..manual and reproduction owners manual says thats the plug..heat shield yes, the factory nightmare..i will get a coil and maps and see if same there too. after seeing thos mess and China plug..i was cnsidering ngk equivalence
Last edited by interpon; Jun 29, 2019 at 08:14 AM.
Forced my hand ...NGK length will work (slightly longer than originals) as at least one heat shield no way getting plug wrench on it..
made in japan..even closer to original size..i noted the ac chine one had slightly shorter threads..
insulator is only difference i see and all other sizing identical to original
fyi i had napa pull their ac delco and was the same as other. Compared on counter
I use the NGK v-groove in my AFR aluminium heads btw.
Says ngk ur4 compatible..look better match than ac delco
what a pos the cap was too..and echlin coil..had to remove some plastic to fit center pin and then it broke installing..
omg what a chore on the wires someone slap who came up with that heat shield..
Spark plug question
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