Spark Plug Gap

SPDNTKT · #1 (**permalink**) 04-14-2009, 04:23 AM

Hello all,
Question regarding spark plug gap. The motor is a side oiler 473 stroker built by Garrett Machine, runnnig an MSD ignition system. I just purchased the car (1,365 miles) and want to service the motor. The plugs are Motorcraft AGSP 32C's. What should the gap be on these plugs? I know with a hot ignition system you can run a wider gap. I haven't measured the gap on the old plugs, but they look overly wide. Any information would be greatly appreciated.

Regards,

Anthony

undy · #2 (**permalink**) 04-14-2009, 04:44 AM

.035" to .040"

Gaz64 · #3 (**permalink**) 04-14-2009, 05:16 AM

Yes, you can run a wider gap, but higher compression doesn't need big gaps.
Big gaps are for stock lean burn engines so they don't misfire up to 5000 or so.

.035 -.040 is a good rule of thumb for a street engine.

The spark will jump at the shortest path to ground, wider gaps encourages crossfire, lead leakage, ignition coil failure etc.

Have a look at some racing engines, they run as small as .018.

era556 · #4 (**permalink**) 04-14-2009, 05:19 AM

I use autolite 3924 and gap is set at .043". With an MSD ignition you can really open up the gap.Been working great for years.

SPDNTKT · #5 (**permalink**) 04-14-2009, 06:30 AM

Thanks to all for the information regarding spark plug gap. God Bless America!

Regards,

Anthony



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