Spark plug gap

[Cabikejumper]

First, I have read quite a few threads on what gap and plug to use. There were too many different variables and gap ranges to come to a conclusion.


Most of you know I am dealing with a random misfire after L&M cams were installed.

talking with a shop last week, they think the gap is blowing out and causing the misfire. This is from telling them symptoms via email. I just haven't heard back from them yet and I know they are pretty busy.

I currently have TR6 plugs gapped at .035. That's what I read to use on another forum but some threads recommend .024,.027, .030, .035 etc.


so, what gap do I really need for MY mods.


2010 GT500
L&M NSR cams
lethal off road x
corsa extreme
VMP 2.5 pulley
idler pulley
thermostat
JLT resinator delete.

 

[GT500RedStripe]

If this is at WOT, try closing the gap to .28 to eliminate spark being blown out.

 

[NightRide]

I had the same setup minus cams tr6 gapped at .030 with good success.

 

[Mainn]

If this is at WOT, try closing the gap to .28 to eliminate spark being blown out.

This. Try it, and if you still have the misfire, you can almost be certain it's not spark blowout caused by the plugs and their gap.

Except, uh, .28 probably isn't a good idea. I think you mean .028".
.028" is what I would try as well.

 

[Cabikejumper]

I will try .028 What is the smallest gap/largest gap. Is there a rule of thumb to follow when modding.


I am
Misfiring 0-2400rpm. At wot (which I've only done twice) it doesn't mis at all. Just cruising it'll miss

 

[Mainn]

I will try .028 What is the smallest gap/largest gap. Is there a rule of thumb to follow when modding.


I am
Misfiring 0-2400rpm. At wot (which I've only done twice) it doesn't mis at all. Just cruising it'll miss

The majority of cars work with a gap somewhere between .028" and .035". The smaller the gap, the less chance of spark blowout.

 

[Blackmax]

Could be coil pack, bad plugs, if you have a Wot box if could be a bad connection. I have always used .025 gap.

 

[Cabikejumper]

No WOT box, plugs are brand new, bad cop would throw a code of whichever cylinder was misfiring thiugh. 99.8% sure that all 8 would not go bad all at once. 100% fine before the cams were installed.

The shop I was talking with got back to me today. They reccomend .028-.030.



Another thing, the shop who installed the cams broke two of the lock tabs on the COP. The used two zip ties on each to keep it plugged in. I removed the ties and wrapped elec tape around the coil and plug to keep it snug until I figure out how to fix the tab they broke.

This was the first plug change since I've owned the car. When I out the cops back on, there is slight play from the cop on the spark plug itself. They push down when I out the cop cover on. Is that a normal?

 

[stkjock]

how much boost?

.028-.030 seems small unless you're at 17+ lbs

I run mine .028 IIRC at 20#

 

[Cabikejumper]

I am right around 13psi

 

[stkjock]

I think .032 would be more than enough at 13#

 

[Mainn]

Yeah, 13psi isn't much. I run a gap of .035" (as evident in my sig) and I'm running 16psi, with no troubles at all. Cams shouldn't affect it all that much.

Only way to test it is by actually doing it and decreasing the gap, though!