The sweet spot varies due to combustion chamber shape, quench area, Intake to Exhaust size ratio, Exhaust valve positioning and flow characteristics. it also determines how much efficiency can be gained.
GRofT is: The gap should be positioned somewhere between the center (horizontal axsis) of the combustion chamber and the exhaust valve center axsis. The objective is to position it in the lowest flow area to get the best ignition and largest flame front.
In the LS6 it can be anywhere between the 1:30 to 3:00 position in the example you provided.
In the LS7 the larger Intake to Exhaust valve size ratio dictates a more critical positioning and a 2:30 position works best tending more toward 3:00.
Getting some sputtering and missfire with my TR5 Iridiums with only 7k miles on them...a little dissapointing...i pulled out the plugs, all are pre-gapped at .035. I wonder if i should put the TR55's in..or would anyone recommend the TR6's?
My LS7 o6 Z06 started cutting out slightly at the strip last year after sitting all Spring from 6000-7000 RPM. It wasn't flat like a plug but a surge.
Voltmeter showed normal across the posts. I had good plugs so I did a battery cell test and found one cell dead. These newer cars computer needs X amount of amps/volts to operate correctly. Changed out bad celled battery which was under warranty, AC Delco. Problem solved. These cars shouldn't be eating plugs like the cars of the 60's did. They eat more battery's then plugs. I've never pulled a bad plug yet with over 150 passes on a few Z06's unless I had a mech/issue. Knock on wood I haven't had any mechanical issues that would cause me to check my plugs. Remember we are still using a 12 volt system changed from 6 volt in 1955 to 12v when the V8 was first introduced to the corvette. In 1956 they added a higher CCA battery but from the 1950's on these cars have had a ton more electonic/electrical demanded on that battery. Check your battery cells if plugs are good.
the car would start bulking under part acceleration i guess running lean since its a hot plug. i then looked up ngk and it recommends the TR6s for the ls7, i then switched to tr6s and car runs awesome now. i have always used tr55s on my ls cars but i guess the ls7 likes a colder plug.
Just finished putting some NGK Iridium plugs in mine an hour ago...TR-5IX with GM high performance red wires...not that it makes much difference or increases performance..but looks nice since they are red, and affordable.
Try going to gmpartsdirect dot com and enter part # 12495519 for these red 8mm wires currently on sale (C5Z06).
Not sure if part# 89018058 for C6Z06 are the red wires or not (you may have to contact them and ask).
Thanks for the info im ordering these for my c5z06 and im going to install the ngk tr6 with these wires. i pulled one plug out to see condition and the gap has increased to .050" thats alittle used as new ones are gapped at .040" so with the new plugs should gain mileage and a more efficient burn
03 Electron Blue z06
Last edited by 4ryanr; 02-14-2013 at 06:13 PM.
TR 6 installed and with the new wires from gmpartshouse
Now to wait for spring to take the car out to test through the rpm levels and see if these plugs will act responsive.
I was wondering why the original plugs when check were all gapped at .060" what would the reason be the difference ? The new ones i check at .040" before installing as suggested.
03 Electron Blue z06
Last edited by Jim Lembo; 02-24-2013 at 09:24 AM.
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