Seems NGK are popular plugs maybe someone can give me a recommendation. I don't have the number and also thought I would give list of mods in case that effects things.

Engine is bored .040,forged pistons, balanced, milled heads (.010), slightly thinner than stock head gaskets, new valve job. Canton road race oil pan.

TB airfoil, CAI, Hooker shortubes (with custom collector work) custom low restriction exhaust, and some other "free mods" including ported stock MAF.

 

Why not run AC delco's. They were kind of expensive at the parts house but good quality and last. The box says they will last 100k but i won't run them that long. I've heard NKG's don't last very long at all.

 

Is there a specific part number of the Delco or NGK plugs I should look for.

If it helps the car spends most of its time at 2000-4000 RPM. From 50 degree weather to mid 90's. I would rather not change plugs for the seasons if that would be needed for the best performance.


I am in a "spec type" autox class so I am looking to get the best performance out of what I have. I am not really looking for any HP numbers just to keep what I currently have crisp.

 

nothing majorly different with your setup over stk. you can run the recommended plug for what a LT1 f-body would use. For NGK it would be a TR55VX (platinum) plug. You may not be able to find this # anymore as NGK has grouped all their platinum plugs into their g-power line. I'm going to do plugs soon on my ride and I'm going to try iridium plugs this time, NGK TR55IX.

hope this helps.

Tony

 

Everyone likes to tell me I'm wasting money on them, but my completely stock engine, with exhaust manifolds went 12.82 @ 106 MPH last year with SF10D Splitfires. With the CC305/ported heads/full weight/stock suspension/full exhaust/shorty header/95,000 mile stock bottom end, this year I've went a 12.25 @ 111 MPH...With the same # Splitfires.

Frank

 

I ran a best of 12.18@110 on a 125 shot on the stock AC Delco plugs for the LT1's. Good plugs. This was on a 4500 lb Impala SS
HVY SS

 

Stick with stock heat range and gap until you add boost or compression...I am running 12:1, so I went to TR6's and .040 gap, and even with a dying opti, I noticed a difference. Realistically, you will not notice a difference in hp or torque with any plug. Correct gap and a non fouled plug is what really matters. TR55's or the equivalent will be perfectly fine.

Now, realistically again, you will not be able to notice a difference in rwhp with a multi point plug like splitfires or Bosch platinum plus 2 or 4's until you do a total ignition system upgrade, and I don't mean a coil. I'm talking Crane Fireball or MSD 6AL or 7AL systems that will alter the way the plug fires. Stock systems will not fire the plug in a way that benefits from the multi point technology.

 

I am using he TR55 IX and like them.