spark plug gap

4179 Views 8 Replies 4 Participants Last post by justacivic, Mar 27, 2001

justacivic

Discussion Starter · Mar 23, 2001

I read this article on the Hot Rod Mag. and want everyone input:
"Savyy hot rodders know better. If the rest of the ignition system is functioning properly, baseline new plugs using the manufacturer's spec, 0.040" for example, then open the gap to 0.050" and test performance. If the engine feels more responsive and the ignition doesn't misfire at high speed, you've made progress. Try increasing the gap another 0.010" and test again. The point is, wider gaps improve combustion as long as the ignition system can bridge the gap. Along with gains in power, lager gaps even increase fuel economy, although such gains usually requre at least a 1k-mile test loop at each gap-setting to yield a consistent pattern."
Another article I read on the NET
"The rule of thumb on plug gaps is to open them up in 0.002" increments at a time. When the car begins to lose power or slow down the go back 0.001"-0.002" and this in most cases is the optimum gap. It is important NEVER TO GO MORE THAN PLUS OR MINUS 0.008"."
I think 0.002" increments is the safer way to increase the plugs gap. Does any body done this?

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1993 B18B1 Power Civic CX

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Luder-xhpx

· #2 · Mar 23, 2001

I run a bigger gap than factory rated on my lude. Approximately 0.045-0.050 gap depending on the plugs I am running.

I do use a aftermarket ignition though... and coil/ wires too. (all crane ignition components and nology's.)

With that coil I use... I have had no problem with spark bridging that gap or misfiring. I could actually prob. go bigger on the gap still even if I want'd to... but I don't.

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93si4ws

· #3 · Mar 23, 2001

it does work and helps you get the most out of your ignition setup, when done correctly.

on our se-r we put ignition and opened the plugs and shaved 3/10th off our quarter.

i took mine .004 over, im still feeling it out before i mess with it again. i dont have any misses. and i think my butt dyno is going numb. im just looking to see if the gas mileage changes.

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don't touch me . . .
aim:jR93si4ws

93vtec4ws

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VeeTec

· #4 · Mar 23, 2001

On the other hand if you have a high compression, like 11.5+, a smaller gap actually works better. Same with forced induction.

The higher the pressure the harder it is for the spark to make the jump. The gains your speaking of generally work better with lower compression motors.

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Warren

93 Prelude VTEC N/A (lots of mods) [email protected]

00 Honda Accord SE (stock)

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VeeTec

· #5 · Mar 23, 2001

Ofcourse you can make an improvement in the spark and increase the gap if you get a good aftermarket ignition.

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93si4ws

· #6 · Mar 23, 2001

i thought thats what we were talking about. i haven't tried this on a factory ignition setup.

our se-r has a relatively low compression at 9:1, and with the msd sci-L and msd wires we've seen nice results.

my jdm h22 hosts an 11:1 c/r and i have the same sci-L, magencores, and a blaster ss. i haven't seen any drastic results, nor have i seen any downfalls. still trying to get a valid reading on mileage. the msd alone gave me 1-2mpg on average, so...

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don't touch me . . .
aim:jR93si4ws

93vtec4ws

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justacivic

Discussion Starter · #7 · Mar 24, 2001

I do have the aftermarket external ignition setup (MSD Red Cap w/Accel??? coil) for my LS hybrid Civic. So open the gap might help right?

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1993 B18B1 Power Civic CX

[This message has been edited by justacivic (edited March 26, 2001).]

[This message has been edited by justacivic (edited March 26, 2001).]

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Luder-xhpx

· #8 · Mar 24, 2001

yeah... you will get better responce and such.

try 0.044-0.050 gap. (if your gauge is mm... it is 1.12mm=0.044 gap... 1.14mm=0.045 gap... all the way to 1.27mm=0.050 gap.)

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justacivic

Discussion Starter · #9 · Mar 27, 2001

I'll open the gap to 0.050" from 0.044 (factory spec.). After some testing I might open the gap more or close the gap depending on the engine response.
Thanks everyone for your input.

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1993 B18B1 Power Civic CX

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