The Great Gap Debate: What should my Spark plug gap be?

Ted Jannetty from Jannetty Racing Enterprises Inc. breaks down the in's and out's of Spark Plug Gap

[jwayne]

Lawnmower sparkplug gap search brought me here.

WOW!Great info in such a short amount of time!
This explains so much about small engines and regular engines.
You just got a subscriber. Keep up the vast knowledge 👏

[foreverstrong]

Thank you very much for sharing your knowledge with the rest of us.

[SmittySmithsonite]

Great info, Ted. The gap thing is just like the octane myth, that higher octane in and of itself will grant you more HP. Another one is the exhaust back-pressure myth, that lack of it will burn valves. Don't know how these tales get started, but there's alot of 'em out there!

On the spark subject, I had a '00 4.3 V6 in a '89 S10 Blazer years back. I had stripped all the FI off and went back to basics - carburetor and HEI ignition. I grabbed a HEI distributor off eBay real cheap, and ran the plugs at the factory setting of .060". I learned a little something about ignitions after that, hahaha! After burning up 2 Chinese HEI modules one after the other, I finally installed a much better quality Echlin module, closed the gap to .45", and still got just .5 MPG less than it did when it was fuel injected (carb was damn close right out of the box, lucky me). No more HEI failures every 4-8k miles either. 😁 That was the best running vehicle in my fleet after that. Prior to that, it had misfiring issues at full throttle that slowly crept down into lower and lower RPM ranges, and would also come and go intermittently. The Chinese just haven't been able to copy an HEI module yet, at least not on eBay. 😉

[elblitzb]

thanks for sharing!!! regards from Chile!!!

[ratdad]

Very good. You're exactly right! I hardly ever agree with anyone! 😁

[FredmChoice]

Thanks Heaps
I purchased new Plugs
NGK TR5IX
And increased the gap to .49thou (and added granatelli zero ohm wires)
What a pleasant difference😍...my LS3 is idling much much smoother and getting better mileage per litre ( before 18.5lts per 100klms, now 17.1lts per 100klms around town
HWY gets 8.9lts per 100klms

[williamtownsend]

I know Joe Mondello liked a .045 for the HEI, not sure why though

[dalelockett]

Thanks for sharing I just validated what you've said by me installing a 1 step colder set of plugs using a .030" gap replacing a set of OEM plugs using a .044" gap & ended up inducing cylinder combustion when I pulled the colder plugs & regapped them from .030" to the low end of OEM spec.... .040" gap & reinstalled the same 1 step colder plugs w\ this widened gap & data logged combustion stability returned to engine that it had w\ the OEM plugs running the .044" gap (the midpoint of the OEM plug gap spec range of .040" to .050"---Ford 4.6L V8 in NA to find reason why only 3 of 8 cyls would experience knock at .70 load & up & not the rest) so my experience just followed what you've said to the letter! Thanks again!

[jamieeisenhower]

I like what you say when the Gap is too small can you get spark knock on normal traffic driving

[BulliKid]

Thank you for this. Thinking of going boost soon. Just regapped oem sparks for na set up

I’m having a running rich condition and I had a tighter spark gap. Do you think this will help fix the issue.

[Rein_Ciarfella]

Thanks for that info. Nothing personal, but how about changing your name back to Giannetti?! 😉👍🔧

[AwakeDude]

BUT all hott rod guys like a small tight GAP not a blown wide-open GAP ?

[maheralmaher]

Hi
Can I gap from 1.1mm to 1.25mm to my spark plugs on my tucsan 2019
2000cm MPFI
Thanks

[KSNOOPE]

Im running a Whipple supercharger on my 6.1 hemi the the spark plugs were pre gapped to .032 when I got the car. should I leave them or go to .050 factory gap?

[Not_Sure_]

I run my sbc at 35 thousandths. 13.5-1cr, solid roller, msd hei, msd 7al, moroso ultra 40s 38 degrees total advance. My combination just likes 35 so that's where it stays

[TommTooTone]

What about a 72 Buick Skylark? 5.7 V8 it says .40 but I'm about to try .50

[seemorebutts]

Thank you brother JR. That is a good perspective. The larger the gap, as long as you have enough voltage to handle it, the more fire. Of course then we get into combustion and what fuel ignites hotter with that spark/fire/explosion to push that piston down. How about mixing a little TNT in the tank? LOLOLOLOL

[jaferessop]

Hi, can a larger gap cause detonation

[FernandoAvella-ym]

What gap for traditional aspirated LPG engines?

[sagirius]

I have a 2020 V6 charger, no engine mods, just an oil catch can. Thinking about upgrading the coils with RIPP coils. Would i gain anything from this? Or not worth it upgrading just coils? And if I do upgrade the coils would I be OK using the the stock mopar V6 Spark plugs? Oh vehicle had only 15, 000 miles don't want to change plugs if I don't need to.

Thanks