420A Plug Gap

[Blitzeclips]

Would there be any altering of this needed during the install? Can I leave the stock gap where it is @ 8psi?

I was thinking of setting it to .28 or .29 after some tuning and uping the boost to keep my idle consistant.

If anyone knows or can help out here, please do! TIA guys..

 

[andymoraitis]

The only time you need to go below .028 is if you're running high boost numbers and the spark is being blown out. Without an MSD, I'd run .026 or .024 at 26 psi or more, but with one, I can still run .030 without a problem. Leave it at .028 and you'll be fine. If it stutters at all and you know the plugs and wires are good, drop it to .026 and see if it improves.

Hope that helps,

Andy

 

[steve]

I don't know how strong the ignition on a 420A is. Start with a stock gap and close the gap down if you have problems with missing under boost. Andys suggestions are accurate for a 4G63 but the 420A may be different.

Steve

 

[BigRand]

for NT's w/ turbo if your running low boost

keep the gap between .32 &.30 and as you go up to high boost, check your gaps and see if you need to close them down to .30-.28

 

[Blitzeclips]

So leave it stock until I turn up the boost?

If I'm missing under boost close the gap gradually until it runs properly?

 

[andymoraitis]

Andys suggestions are accurate for a 4G63 but the 420A may be different.

Steve

Doh! I can't believe I missed that...

 

[steve]

If I'm missing under boost close the gap gradually until it runs properly?

That's my understanding. You want to run the biggest gap that you can.

Steve

 

[Blitzeclips]

hmm... Thats interesting..

From my assumptions, the further the spark equals less feul burnt because its got a larger gap from the pistons... Runnning the gaps closer would give more feul therefore creating a stronger spark under higher pressure (AKA-Boost)

Sound correct? I want to know why the gaps are altered so I can understand the sytem better for future reference..

So enlighten me if I'm wrong.. or off per se..

Thanks again guys.

 

[steve]

From my assumptions, the further the spark equals less feul burnt because its got a larger gap from the pistons... Runnning the gaps closer would give more feul therefore creating a stronger spark under higher pressure (AKA-Boost)

So enlighten me if I'm wrong.

From http://www.ngksparkplugs.com/techinfo/spark_plugs/installation.asp?nav=31300&country=US

"Most experienced tuners know that opening gaps up to present a larger spark to the air/fuel mixture maximizes burn efficiency. It is for this reason that most racers add high power ignition systems. The added power allows them to open the gap yet still provide a strong spark."

How big a gap you can run is depends on the rest of the ignition system but the goal is to run as big a gap as you can and not misfire.

A couple more references:
http://www.ngkntk.co.uk/technicaltips/sparkpluggap.asp
http://en.wikipedia.org/wiki/Spark_plug#Spark_plug_gap


Steve