went in to parts store to pick up some new spark plugs, and i thought i was in school...the sales person gave me his 2 cents and then some!!!

he told me because im running a mild cam, headers, 650 carb., i should use a diff. spark plug! , now all what they had in the store was autolite(cheap sh!t)computer calls for Autolite 65, he told me to run Autolite 64, claims to be a better plug for my app! is this true or he is just lost in another planet??

3923 autolite . the champ Je11y's are fer the big stuff. who do you think you are? mister big stuff....

raelians are from israelia?

the 65's are symbolically correct.

RN12YC Champion plugs. Have Champions for eons and not had a problem with them. They Have been the OEM plugs on Mopars for as long as I can remember and I have been involve with Mopars for 40 + years.

64 is a little colder plug then the 65. I use 64`s with no problems. Champions worked well for me too. Mike

The 65 is close to a N14Y champion which is a hotter plug. Performance engines usually need a colder range plug. From what I remember a 64 plug is closer to a N12Y champion. Mike

because your car is cooler..

I ran one heat range lower for a while to see what it looked like in one cylinder for a test.

I don't kno what you mean by mild but if it runs on pump gas with a full exh system (street car)and no overheating issues then I would probably just run a stock 360 plug. Colder plugs foul easier so if it's not needed then why bother ???
If this is a race only car go ahead and try a colder plug. some like to tune for different tracks /track conditions by changing plugs & adjusting timing.
It"s your call, really

anew plug on the market is the E-3 diamond fire
spodda save gas and give a cupilla horse power gain, about 5 depending on the application this i did sea this demoed on a dyno on tv if you believe everything you sea on TV

The heat range of the plug is an indicator of how quickly the plug cools off between firings. A colder heat range will cool off quicker than a hotter range.

You want to run as hot a plug as the engine can stand, this ensures that deposits get burnt off so the engine will run well for a long time. To hot a plug and it can cause detonation and the tips will erode away faster.

The stock heat range is just fine, one heat range cooler will not make a difference if the engine was running well with the stock range.

The 3923 mentioned above is one heat range cooler, a 3924 is stock. These plugs have a 5/8" hex for the socket (but are the same other wise) instead of the 13/16" of the 64 or 65. The 5/8" hex makes it easier getting the plug past header tubes, the 3924 plug is what comes stock in 3.9/5.2/5.9 liter magnum engines.

I typically use Autolites simply because the local Walmart has them and it saves me a few miles of driving to a parts store to get something else. I would avoid the gimik plugs like E3 and Splitfires, once the voltage potential builds up enough to jump a spark you only get one regardless of how many or the configuration of the ground electrode.

The platinum and an iridium plugs last longer than a conventional plug and that is why they exist, not to make more power or increase mileage. They were developed so the manufacturers could extend plug changes to 100,000 miles.