I have the tr55's in there right now and for 18 bucks for a set its hard to beat but a mechanic at work said that the delco's were worth every bit of 6 bucks a piece after having tried the similarly priced, to the tr55 that is, bosch unit. I dont have stumbling like he had from it but still why are they 3 times as expensive? Are they worth it? and damn the iridium ones are even more....

 

My mechanic told me the same thing, he worked for a chevy dealership. I didnt notice a damn difference. Stick to NGK or Autolites.
This is the order of plugs Ive had installed the past year...
ACD>NGK>ACD>NGK>Autolites... and so far I like the autolites the best.

 

If they don't say AC,Champion or Autolite don't waste your time bringing them home.
The plugs made over THERE don't do as well in American Muscle as in Ricer's.

 

I'll offer a slightly differing opinion.... my stock AC/Delco platinum plugs had a habit of losing the tiny platinum pucks. Lose one and you have a 0.075" gap, lose both pucks and you have a 0.100" gap. Numerous people have reported similar problems with the AC/Delco platinum plugs.

I've used NGK and AutoLite for low level nitrous and both worked fine. My preference between the two would be the AutoLites. I run some Champion plugs with the 300-shot. Others have had good luck with Rapid Fires in bolt-on setups.

Interestingly, my 2001 Silverado pickup appears to have come from the factory with NGK plugs....

 

I have not had any trouble with the tr55's but just thought I would ask, I may try the autolights this time around... also my car is simply a bolt on car with headers so is there any sense in getting iridium plugs or platinum or anything out of the ordinary and what do those metals do anyhow? I ll search for the autolights...

 

The platinum pucks are added to the center electrode and the ground strap ("double" platinum) to resist erosion of the electrodes from the high voltage discharge. That's the way GM thinks you can let the plugs go for 100K miles without replacement. If you use a non-platinum plug you might find you need to replace them at 20-25K miles or so, because of the gap opening up.

I don't know anything about the supposed or real benefits of the Irridium plugs.

 

I use "modified" plain copper Autolites... swap them out every 5-10K miles (It's simple with Hooker LTs, takes less than 30 minutes, and normally do it while I'm waiting for my oil to drain for an oil change). I had issues with the Iridum (sp?) and Plat. plugs in the past with the pucks going out, and just wearing out in general and running like crap, and at $5-$6/plug it gets expensive... whereas the $1/plug for the copper Autolites and just swapping them out at every oil change is sweet for me.

 

Yeah I think im just going to go with the tr55's again and gap them to about .04" since they are about .065 right now after nearly 20k miles. Hopefully it will keep it closer to the recomended .050 for more of the spark plug's life.