teej281

If youre gonna replace the plugs, dont put TR6's in because they are one heat range cooler than stock and thats no good.

cliffyk

For nearly any "streetable" application there's nothing "better" about the TR6s.

People running very high compression and/or high boost use them because when close gapped they were more resistant to spark "blow-out" and production of a weak spark. This occurs when the chamber pressure is quite high or when using certain fuels and AFRs.

It requires a higher voltage to ionise the gap under those conditions, and a fresh set of non-resistor, conventional center electrode plugs is one way (at one time the only way) of meeting that challenge. The downside is that they don't last very long (30k to as little as 15k miles), particularly with a modern EDIS (Electronic Distributor-less Ignition) or COP (Coil on Plug) based system where there is enough potential voltage to fire them right down to a nub--with an ever increasing gap--in rather short order.

This leads to why I chose the word "were" above. These modern ignition ignition systems have more than enough potential to blow through all but the most demanding combustion chamber conditions, and produce a nicely energetic spark.

Coupled with fine wire, precious metal, plugs the EDIS and COP systems will provide dependable, high performance, service for 100k miles or more.

teej281

I have TR6's now cliff and they have about 30k on them...should I replace them? And i know its dumb to have them in my car...put them in when I didnt know any better. lol

cliffyk

I would at least pull them out and look at them--at 30k miles they will likely have a gap you could drive a freight train through.

Two problems with that. First is that the widened gap requires a higher voltage (and more power) to ionise--more power = more heat dissipated in the COP = increased chance of insulation breakdown = failed COP.

Also sometime in the not too far distant future, assuming the COP doesn't fail first, the gap will grow to where the COP cannot fire the plug--or worse yet fires it very weakly which can lead to a weak initial flame and detonation.

devongarver

I got my TR-55's really cheap on ebay, if you decide to switch plugs to the normal heat range lol

teej281

Yea, im gonna swap back to normal heat range, which i thought was the TR7's? I thought the TR55's were another range colder than TR6's? And i've got problems with detonation i think because below 1500rpm if i put any load on the motor it seems to ping and I cant get it to go away no matter what gas I put in it. And its a canned tune pretty much with a/f ratios datalogged and additions/subtractions calculated manually and values plugged in to make sure they are correct. So looks like its time for new plugs.

devongarver

MOTORCRAFT

PART# / HEAT RANGE
AWSF-32C / stock heat range - copper plug
AWSF-22C / 1 Heat range colder - copper plug
AWSFA-12C / 2 Hea range cooler - copper plug
AGSF-32C/ Recommended for FRPP heads(not sure on heat range)

NGK

PART# / HEAT RANGE
TR-55/ 3951/ Stock Heat Range
TR-6/ 4177/ 1 Step Colder
BP7EFS (PN - 3526) BR7EF (PN - 3346) two steps
R5724-8 (PN - 7317) two and a half steps
R5724-9 (PN - 7891) three steps
R5724-10 (PN - 7993) four steps

AUTOLITE

PART# / HEAT RANGE
764s / Stock
103s / 1 heat range cooler
AR94 / 2 heat range cooler
AR93 / 3 heat range cooler
AR92 / 4 heat range cooler

CHAMPION

PART# / HEAT RANGE
YS-59C / -3 or -4 below stock heat range

DENSO

PART# / HEAT RANGE
IT16 / stock heat
IT20 / -1 heat range
IT22 / -2 heat range
IT24 / -3 heat range

teej281

Sounds reasonable to me. lol

cliffyk

The fact that it is pinging means the values are not correct.

Cooler plugs may help a bit, but if they do then your timing and/or fueling are dangerously close to the "edge", I.e. too far advanced and/or too lean.

teej281

I wish I could have you do a tune for my car cliffy. lol