I HAVE AN 05 RAM 1500 5.7 HEMI my spark plugs are goin on about 40k and have a gap of .054 the spec is .045 do u think that is why im not getting the gas mileage i should ?

 

i def can be. You should change the stock plugs every 30kmi. They are plain ole coppers. Replace them with plain ole coppers. Don't waste your money on platinum or iridium. The Hemi requires 16 plugs. Copper is soft on the pocket at that point...lol Coppers the best conductor hands down. Make sure the gap is within specs. The .054" is running the cylinders hot and could be causing them to fire late or even misfire on higher revs causing bad gas mileage. Either way, the Hemi's good for 13city/17highway if you were to combine everyone averages. both ridiculously high and low. Regardless of what you are getting, I'd replace the plugs.
Bad plugs can do bad things. Just detonation alone can break aprt the skirting on the pistons. has happened to Hemi's before because guys use 87 octane instead of 89 like recommended. Also, that is a common thing among the Ford Modular motors when pinging has been occuring for a while due to low octane gas, especially with the loads of Ethanol they are putting into the gas nowadays.

 

Shoud've replaced them while you had them out. Don't put the cheap champion coppers back in unless you want to replace them again in 30k with the gap being off in half that. Yes, copper is the best conductor that's why even the high end plugs use copper for the core...it's the tips that give plugs longer life, maintaining gap, anti-errosion/oxidation and all that crap. NGK makes a great plug and their platinums aren't expensive.

 

haha thanks guys i thought it was that plus using super helps get some better gas mileage in the hemi