Going to get car dyno tuned and would like to have everything top notch for the tune. I run high octane all the time, so burning a hot plug isn't a problem.
Best advise?

 

On my cammed/bolt-ons c5z - NGK's TR55's gapped to .040. IT was recommended by the tuning shop.

 

Agree. However, it is best to go TR5. The 55 and 5 are the same, but the 5 comes gapped at .040. If you gap the 55, which comes gapped at .055, to .040, the ground strap is bent and shrouds the electrode. So, if you want a larger gap, do TR55s, if you want smaller, TR5. Everything else about the plugs are the same.

 

Good to know, thanks. Will switch them up this season.

 

What would be a typical interval to change them at? 10k 20k?

 

I'm glad you said that. As far as I would have known, I'd told you just tr55's; I had no clue that plugs were altered so much from the old style, or that plugs had become so fickle.

I really appreciate the help. Thank you.

 

Ha ha, I asked for one thing and got something totally different. I asked for the TR5's as you had prescribed, but just checked my box and they are NGK IridiumIX plugs.
Any thoughts to quality? I figure they are going back for the TR5's, but thought I'd see if this is even a decent plug.

 

I just picked up a set of ngk tr55 and they're gap at 55. Works pretty good.

 

Seconded, mine were from Amazon, and half of them were bent wayyyy out of spec.


I learned two things,

• Don't order spark plugs from Amazon!
• How to gap a spark plug.

 

IF,,,,,,, you are going to get the car dyno tuned, here are some things that I highly recommend:

New PLUGS. "Already in progress".
New Plug Wires
CLEAN THE MAF
Clean the throttle body/throttle blade.
Check ALL your vacuum lines and the air ducting between the MAF and throttle body and make sure that they are properly sealed/air tight!

If you'er O2 sensors are old, I STRONGLY recommend replacing them with new ones.

Once you have that base line and the car starts to run poorly in the future, you should only have to FIX something stated above to get back to a good running engine.

Bill

 

I couldn't agree more.

I went ahead and picked up AC Delco coils from the Chevy house.

After returning the wrong plugs, I've got the correct plugs you suggested.

I bought Bosch O2's: up stream & down stream. I'm curious if you think those are ok?

I also just replaced the cats and I went with a high performance cat. While I was there, I went ahead and removed my Borla stingers and went with straight pipes over the axles. I like it better. I get a little weight savings and it seems to actually run smoother.

Also, I want to see what your thoughts on GM Hot Wires might be. I have JBA's on the car currently- I didn't install them- they were on the car when I bought it but I'd like for the new to be a good, solid plug wire.

I run a high grade silicone coupler from the intake to the tb; the accordion style couplers create too much air turbulence and tend to rip.

I am wondering if you have or know of a URL link for a good map/layout of a 99 c5 vacuum & pressure line system?
I can spray the vacuum lines with carb spray and listen for idle changes, and I can hit the pressures lines with soapy water to look for bubbles, but a preimptive which-is-which is more helpful.

By the way, you've been graciously helpful & and I just want to say thanks. People like yourself and all the others so willing to generously offer up so much help, well, flat out make this forum and being a Corvette owner so great. I also own a 03 Cobra and the "ford" (Cobra, mustang, set) forums/websites & members are not nearly as knowledgeable, helpful, and most of the time, Without rude attitudes.