Spark Plug Gap Load on Coils

[Soft Cars]

Would a set of spark plugs gapped to .040'' be less of a load on the coils than a set of plugs gapped to .060'' ?

The reason why I ask is because Denso specifies .040'' for my application while all the other plug manufacturers including ACDelco specify .060''.

 

[wpod]

Yes with in the usual, electricity takes the easiest path to return the current to source.

 

[atikovi]

The reason why I ask is because Denso specifies .040'' for my application while all the other plug manufacturers including ACDelco specify .060''.

What does the car manufacturer specify?

 

[Soft Cars]

What does the car manufacturer specify?

.060''

 

[atikovi]

If it's a GM car, I would go with that. The coils would be designed to handle it. Bigger gap usually means a fatter spark and better combustion, economy and emissions.

 

[Soft Cars]

If it's a GM car, I would go with that. The coils would be designed to handle it. Bigger gap usually means a fatter spark and better combustion, economy and emissions.

Yes I don't know why Denso specifies .040''.

 

[barryh]

The 40 thou gaps will put less stress on the coils because the plugs will fire at a lower voltage but is there any benefit if the coils were designed for 60 thou gaps. 60 thou will have been specified for a reason which will be it produces the optimum spark and the best ignition performance without misfires. You will in any case be putting less stress on the coils with new 60 thou plugs than you were with old ones.

 

[dubber09]

Different plugs for the same engine may have diffrent gaps, don't be alarmed, go with what plug manufacturer says for the engine.
Example from my recent Volvo plug job - Volvo (NGK?) and NGK plugs show one gap 0.030, Denso 0.040 and others - other values.

 

[Jetronic]

the voltage to fire and maintain the spark is lower with smaller gap, but the spark lasts longer. Not sure there's much in it. My car specifies 0.030" with fairly potent coils. but turbo so...

 

[Soft Cars]

The 40 thou gaps will put less stress on the coils because the plugs will fire at a lower voltage but is there any benefit if the coils were designed for 60 thou gaps. 60 thou will have been specified for a reason which will be it produces the optimum spark and the best ignition performance without misfires. You will in any case be putting less stress on the coils with new 60 thou plugs than you were with old ones.

So would it be safer to avoid Denso plugs since they specify their own gap?

 

[CharlieBauer]

So would it be safer to avoid Denso plugs since they specify their own gap?

Yes. And generally speaking, the OE plug is best. Compare aftermarket options to that and verify the gap from the owner's manual. Sometimes the information about what the factory gap is that is provided with the spark plug is incorrect, even for the OE product where that same spark plug can apply to more than one engine.

The main reason to not use OE is to upgrade to finewire and iridium which will use less voltage compared to regular plugs. But again, you should verify gap as well as heat range is correct.

 

[spasm3]

I generally under gap by .005.

 

[dubber09]

Technically, smaller gap with very same plug will give better more reliable ignition, larger gap will give a bit more complete burn.
Different plugs may have diff gap specs for the same application.
I'm not talking about heat range spec here while some applications/engines may benefit from diff than stock heat range plugs.

 

[Rhymingmechanic]

Yes I don't know why Denso specifies .040''.

The Denso plug could be a different design vs. the original.

For example, the GM pickups around 2000 came with platinum plugs gapped at .060. GM later revised their recommendation to an iridium plug with a .040 or maybe .044 gap. So the new plug specified by the manufacturer itself conflicted with the underhood decal and the owner's manual.

 

[willbur]

Would a set of spark plugs gapped to .040'' be less of a load on the coils than a set of plugs gapped to .060'' ?

The reason why I ask is because Denso specifies .040'' for my application while all the other plug manufacturers including ACDelco specify .060''.

Denso have a tech support line or website? Ask there. They could help you rather than 100 opinions here...LOL

 

[Sam_Julier]

I run NGK G-Power platinum plugs in the 240s.

The gap out of the box is never the Volvo .030 spec. Always larger.

They look new when I replace them at 20,000 miles. The rotor and cap don’t look as nice. Which is why I replace the plugs, rotor and cap as a set. The engine runs beautifully.