spark plug gap for headswapped cars

[tomustang]

My personal experience is that .035 is NO FREEGIN GOOD for a N/A Stang. When I gapped the plugs to the factory setting, the car ran MUCH better. I'm sticking with .053-.057.

See when I done the swap with the stock gap I didn't feel any difference in power at all, didn't even notice anything. After I tried .40 I was sold and felt the gain.

 

[CobraM23]

At first I had TR-55's in at .054 and I had detonation and missing every once in awhile. I gapped them down to .035 and the car runs a hell of a lot better, no detonation at WOT or missing to be heard of. It does ping going up a hill in OD but thats to be expected. My car runs better with the smaller gap.

 

[tomustang]

At first I had TR-55's in at .054 and I had detonation and missing every once in awhile. I gapped them down to .035 and the car runs a hell of a lot better, no detonation at WOT or missing to be heard of. It does ping going up a hill in OD but thats to be expected. My car runs better with the smaller gap.

What gas?

 

[mrvax]

See when I done the swap with the stock gap I didn't feel any difference in power at all, didn't even notice anything. After I tried .40 I was sold and felt the gain.

Are you saying you did the PI swap, gapped the plugs to factory specs and did not feel gains from the swap???

 

[RysRed96GT]

i at least recall for mine that it was smoother going from the .054 gap to .040. my current plugs, though they're a year old, are gapped to .040 and the engine purrs.

 

[tomustang]

Are you saying you did the PI swap, gapped the plugs to factory specs and did not feel gains from the swap???

Well the stock plugs were gapped to factory specs when I bought them

 

[CobraM23]

What gas?

93

 

[mrvax]

Well the stock plugs were gapped to factory specs when I bought them

Yes but what I'm asking is are you saying you did the headswap and felt no gains until you gapped the plugs to .040?

 

[tomustang]

Yes but what I'm asking is are you saying you did the headswap and felt no gains until you gapped the plugs to .040?

Yes, It was more like a struggle feeling than a gain,

 

[mrvax]

This whole thing with the smaller gap doesn't make sence to me. You'd think that by having the larger gap, there would be a slightly longer burn time, much like the MSD (multi-spark-discharge) product. A short gap would have a quick burn.

Provided of course that you had enough voltage to carry the spark across the larger gap just seems like it would work better. I know it did in my case but I'm surprised by the people who say they felt .040 was better.

 

[billyfe390]

If you felt a gain by reducing the gap you have weak coils or bad plug wires.

If its NA you make the most power with the widest gap.

 

[tomustang]

This whole thing with the smaller gap doesn't make sence to me. You'd think that by having the larger gap, there would be a slightly longer burn time, much like the MSD (multi-spark-discharge) product. A short gap would have a quick burn.

Provided of course that you had enough voltage to carry the spark across the larger gap just seems like it would work better. I know it did in my case but I'm surprised by the people who say they felt .040 was better.

Higher compression runs better with a smaller gap 9.0:1 to 10.3-5:1

Something many do not know, is that with Higher Compression ratios and Superchargers as well as Nitrous, in many cases smaller spark plug gaps must be used as well as the use of a much hotter ignition system (see above). These higher cylinder pressures require more energy to jump the spark plug gap.

http://www.centuryperformance.com/spark.asp

3. Gapping

Since the gap size has a direct affect on the spark plug's tip temperature and on the voltage necessary to ionise (light) the air/fuel mixture, careful attention is required. While it is a popular misconception that plugs are pre-gapped from the factory, the fact remains that the gap must be adjusted for the vehicle that the spark plug is intended for. Those with modified engines must remember that a modified engine with higher compression or forced induction will typically require a smaller gap settings (to ensure ignitability in these denser air/fuel mixtures). As a rule, the more power you are making, the smaller the gap you will need.

http://www.ngkspark.com.au/tech_index.htm?http://www.ngkspark.com.au/pages/tech_content.htm

If you felt a gain by reducing the gap you have weak coils or bad plug wires.

That is also true.

 

[DropTopPony]

My denso's are gapped at .055 but i do have Screamon Deamon coil packs and livewires for a hotter spark. That is what they suggested with denso plugs...Runs smooth.

 

[CanadaStang]

My 98' ran great after the Pi swap with the plugs gapped at .054. Idled and ran the same as before the swap only the power difference was day-night compared to before.