Spark plug gap

85GTStangGuy said:

0.43 and 0.52 gaps seem pretty big..... like, maybe, 10 times too big!

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CAMTWO1070 said:

If the OP has a Sniper setup theres a dropdown menu that you can choose the type of ignition and also the dwell can be modified to suit the spark output...

In all my years tuning and whatnot Ive learned alot from entities like MSD before MSD went chinese and melded with Holley...

Compression up to 10.25:1 gap can be safely between .050" - .060" wide...A wider gap creates a wider spark arc to fire the mix more intensely in the cylinder..

The compression of the engine dictates the initial sparkplug setting and therefore if a stock engine with GT40 heads runs about 8.5:1 compression you need to verify if your engine is making more or less compression than the stock engine because we all know that stock headgaskets are usually just .020" thick shims and the Felpro stuff starts out at .042" of thickness so its a matter of the preference of the engine as far as heatrange etc to fire the mix the most efficient way possible especially if the compression isnt up to par or higher than it previously was...

One thing for sure is with aluminum heads you want sparkplugs with a hotter heatrange or run the engine up over 200 degrees which I can see no benefit in doing as extra heat will expand metal parts even further.....

In my 410 w/ 10.25:1 comp and Edelbrock heads is it likes NGK V-groove racing plugs with .058" wide gaps and a 180 degree thermostat to make optimal power seeings I run a chip and dont run in closed loop ever because I dont want the ECU messing with my fuel trims......LOL

Best mod for any car with an EEC-IV ECU is adding a wideband controller into the EGR slot ..........

It makes a huge world of difference in the way the engine reacts and stays in tune with a wideband controller integrated in.....Even on a bone stock car!!

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