Spark plug - The 1947 - Present Chevrolet & GMC Truck Message Board Network

TRC LEE · 03-23-2017, 09:58 PM

Having spark plug issues. Need some help. 66 truck with 250. Original plug is AC 46N. Suggested replacement is AC R44XLS. Which has a 13/16 head. The threads and reach seem fine but when I get the plug into the head there is no room left for a socket to tighten it up. I am wondering if the head has been changed somewhere along the way or am I missing something. What plugs are you running in your 250? The plugs that were in the truck when I bought it are an NGK iridium plug UR5GP that is so short it really doesn't seem to be the correct plug.

03-23-2017, 09:58 PM	#1
TRC LEE Registered User Join Date: Jun 2015 Location: Chattanooga Tennessee Posts: 5	Spark plug Having spark plug issues. Need some help. 66 truck with 250. Original plug is AC 46N. Suggested replacement is AC R44XLS. Which has a 13/16 head. The threads and reach seem fine but when I get the plug into the head there is no room left for a socket to tighten it up. I am wondering if the head has been changed somewhere along the way or am I missing something. What plugs are you running in your 250? The plugs that were in the truck when I bought it are an NGK iridium plug UR5GP that is so short it really doesn't seem to be the correct plug.



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