Hello, all I have a question, I would like to replace the plugs i have. I am currently running a set of acell #414S plugs, I cant recall the heat range of these , and a search has also turned up nothing as well, The plugs that i am looking for must fit AL AFR heads with the gasketed type. The reason i purchased the Acell ones were because they were the short version and they provided more clearence for my wires as the SLP pipes are very close. Any way were do the Acell #414s plugs fall in the heat range chart? What the heck should i be running for a plug in a street engine? Thank you , looking forward to your replies.

The 414S is considered a race plug. Not exactly what you want on the street.

The last digit is the heat range. Yours is a #4 which is cold. With Accel plugs, the higher the number, the hotter the plug. If your plugs are not fouling up then the heat range should be ok. If they are fouling, go up one heat range.

Because it's a special shorty plug for headers, I don't see a cross reference to any other brand.

Thank you for the reply,

I was just wondering "where" on the cold/hot scale they were at. I am chasing a "Ping" and just wanted to eliminate the plugs as a possible source.Thanks again.

Plug temperature is the temperature at the tip of the plug and has nothing to do with engine temperature. Rule of thumb is to run the coldest plugs possible without them fouling. Changing jetting or timing will change the plug temperature.

Too hot a plug and the tip melts away. Too cold a plug and it can't burn off the deposits and fouls up.

I just told him before that a 'too hot' plug can stay hot while the engine is running and be a hot spot - ie a source of detonation.

Since those are cold plugs, i'd put it out of mind. I'd still look for the HEAT LINE though.

He's got an injected car with loads of compression ratio and a dinky small cam. Not much fix for that.

GTA - I never asked, did you get ping when you were on the dyno or has this recently cam about? How do the plugs look? ie. can you tell if it's detonating on a certain cylinder in particular? One injector might be partially plugged/leaking causing it to run lean and cause knock. Do you have a temp gun? Try shooting each header after a good hard run and see if there's much deviation. With port injection the mixture is a lot more consistent cylinder to cylinder. (You should see the plugs I just pulled out of mine, you can easily tell which was where, one side of the RPM intake manifold was lean )

Sonix,

I Just was curious about the plug heat range, and they look great with no signs of detonation.As for having a "funky" injector i should not have that problem as i have just upgraded my injectors..got rid of the poor orginal Multecs in favor of a new set of #24's. So I have not been able to grab a new data log of the car and will be unable to do so untill sometime in May.

In regards to my KR it apears in the higher RPM ranges 3000 Plus, but i have been unable to rule out valve train noise ( rollor rockers ) and the KR logs are never consistant, some times it will pull quite a bit then the very next run it will only pull about 2-3 *. Hopefully it was a poor injector but time will tell. thanks folks for the input.

Sonix, you have mail!