I was thinking of changing my plugs on my 2000 4.8 Vortech supercharged truck.
I have been researching gaps for supercharged motors. My plugs are currently gaped at .50. From the searching I've done it seems like my people are saying my plugs should be gaped at .35.
Upon inspection of the plug I see that it has a burnt line that runs down the insulator tip near the ground strap or side electrode. I talked to my buddy and he said this is usually cause by too large of a gap.
The truck runs pretty much ok. It needs tuning which i am in the process of. I just have this slight stumble that happens about every 30 seconds driving at a steady speed. No stumbles at WOT or accelleration. You feel it a lot more so when the a/c is on. Without the a/c on you really have to pay attention to notice it.
So, what do you guys think? What Gap do i need? Ideas on the burnt line on the insulator tip means too much gap?

 

Alrighty then. Guess I'll gap them at .40 and see what happens.

 

If the gap is too large, it will feel like a rev limiter almost when you go WOT. It will still run fine at part throttle unless they are way too big. Factory gaps are .060 I believe, and cruising speed the engine load is still the same as factory. What kind of plugs? Sure there are no cracks?

 

I've got NGK TR6's now gaped at .45. The fan shroud cover says to gap factory plugs at .60. They were at .50 until this morning. It went on a hour drive and i think it ran better. I really had no issue with how it runs when they are gaped at .50. Other then a slight stumble every 30 seconds with the a/c on. A/c off you can barley feel that stumble, but its still there though.
Its still does does the "stumble" with the new gap of .45. Its not as bad as it was with the larger gap. The stumble just feels like the motor takes on a brief second of load. Like a fraction of a second. You can hear the exhaust note change to what it would sound like under a little load as well.
I just need to change the plugs anyways. It doesn't require too much energy. I just don't know if .50 is cold enough.

 

Most people just stay with the .035 they come at.

 

I wouldnt do .045 with a blower. .035 should be good unless you start running over 9psi or so. You sure that "load" you feel isn't just the AC compressor kicking on? If so, that's normal. Also, when you add forced induction, the factory recommended .060" gap goes out the window, along with many other things.

 

If you gap them that wide you will probably blow your spark out under boost. What plugs are you running? Most people run NGK TR6's as they come at .035. Do a search and you will see a consensus.

 

I'm going to get some new TR6's with the .35 gap. I haven't owned the truck long. Trying to work out the bugs. I guess the previous owner just didn't know what he was doing with his .50 gap.

 

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