Hey guys,

I'm looking to head to the dyno next week to finally get my car tuned (AI heads/cam + all bolt-ons) by the guys at Second Street Speed. I'm going to switch (per my tuner) to a colder plug (TR6s) from the TR55s I have now.

My plugs in the car now were never indexed, so who knows where the gap is positioned. I'm going to index them before I get to the dyno.

My question is, where are you pointing the gap? Most people just point the gap between the intake and exhaust valves, but would it make more sense to point it towards one valve or the other? I know on a lower compression engine it wouldn't matter much, but I want to make sure I have ALL my bases covered. Also, if I'm being too **** about it, just tell me. Heh...

Any thoughts? Thanks in advance.

 

Most of the time the plugs is indexed toward the intake valve. However, some engines work better when it's pointed toward the exhaust valve. Not many though. However in all cases, you won't even get a 1% gain. Way to much work for way too little payoff. In a dragster, sure. It's 1% of a much bigger number and it's easy to get access to the plugs.

Let it go.

 

That's all I needed to know. Even if it's half of 1%, still 2 or 3 HP. I'm changing the plugs anyway.

Thanks for the input.

 

Actually the dyno is needed to do the indexing. Just merely pointing them without checking may not do anything. So unless you have a small fortune to pay for dyno time while someone pulls and shims each of the 8 plugs. You are still probably wasting your time.

And one other point. You don't need to replace the plugs, merely shim them till they stop in correct position. But if I remember correctly, (help me out here) aren't the plugs used in the LT1 a tapered seat plug????? I can't for the life of me remember.

So how do tapered seat plugs work with indexing shims???? Maybe Rich can chime in here.

If they are gasket seal plugs I could see it but if they are tapered seat (again I can't remember) I don't see them working well.

 

Ask Bill or Lon at Second Street Speed.

I supsect they may tell you not to worry about it.

 

Hahaha...I'll do that.

Thanks Fred.

 

They do make tapered seat indexing washers for typical 14mm threads. And about changing my plugs, I'm changing them first, so thought indexing might not be a bad idea while I'm at it (going from a TR55 to a TR6).