So I needed to change my spark plugs in my 03 Silverado 5.3L. Well I went out and got AC Delco plugs (41-985) and they are preset to .040 they even say not to deviate from the set gaping, Well when I pulled out the old ones they where gaped at .060 (41-974), but when went to look up the old ones on AC Delco's site they weren't there. So my question is did they change the gaping requirements or did the last person that changed plugs put the wrong ones in?

Becuase now my RPM gauge needle does climb as smoothly when I Rev the engine in neutral.

 

I think someone may have installed the wrong plugs, you should be able to look at the emissions label under the hood and find the proper gap setting listed.

 

Somone installed wrong plugs if parts store gave you right plu for the right vehicle the acdelcos will be right as they come pregaped

 

Ignition System Specifications

Application .................................................. ........Specification
Firing Order .................................................. .....1-8-7-2-6-5-4-3
Spark Plug Wire Resistance ..................................1000 ohms per ft
Spark Plug Torque ..............................................15 N·m ..........11 lb ft
Spark Plug Gap .................................................1 .01 mm......... 0.040 in
Spark Plug Type ...............................................125 71164 [GM part number]
.................................................. ......................41-985 [AC Delco number]

 

Ok thats what I thought, but what kinda of damage can be done with that gaping size difference if any?

 

it will just run like crap

 

Overheating of spark plugs and then the plugs will get damaged faster. also you will have carbon particles floating around in your combustion chambers which , after a while, will ruin your "valves" . (I NEED AN ENGLISH DICTIONARY !!!!! The thingies that go up and down in your engine block ).