Are the Autolite AR-13 spark plugs considered a cold plug? That is what the shop put in my motor when they built it and I was wondering if there might be a better one for on the street.
camaro man
thanks for the chart. So it looks like the difference between the AR13 and the AR94 is the reach. Is it possible with 049 iron heads with valve size 2.19 intake, 1.88 exhaust, flat top 9.3 comp pistons there would be any problem with the 1/4 inch longer reach? I'm just wondering why the builder put in plugs for a small block. What would the performace difference be switching to the longer reach?
Marc if you trust a shop to build an engine you should be able to trust their plug choice too. What symptoms are you having that suggest you need a colder or different plug? Have you asked the builder why he chose the plug he did?
I have been thinking about someday adding a little nitrous later this year and I didn't know where the AR 13's fell in the hot to cold range. As far as the motor is concerned it runs fine, but the plugs aren't burning clean, they're usually on the black side. I think the carb might be jetted a little rich for daily driving. Next time I see the builder I'll ask him.
AR series plugs run 1-5... thats a medium heat. (second number)
1= cold
5=hotest
The "over seas" like NGK are 1=hotest and colder as they go up.
1= cold
5=hotest
The "over seas" like NGK are 1=hotest and colder as they go up.
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