Spark plug side gapping

[Wietse]

Learned a new thing, never heard about it before...spark plug side gapping.
I had read up about it in several articles on the web, seems like there is not a real gain as statements like +10Hp or anything like that; even then that is not what i was looking for.
But it does tell how the flame path improves as the A/F mixture seems more exposed to the spark and heat generated and gives a better flame path.

Anyone here modifying their spark plugs, or running some side gap style plugs?
Since my engine is not the easiest in fine tuning i was wondering if it will help providing a better combustion?

Here is, one of many, sites explaining the side gapping.
https://www.hotrod.com/articles/does-side-gapping-spark-plugs-work/

 

[beanhead]

Well, just my own experience with them, but I've used the Autolite 'AR' race-series plugs which have that cut-back electrode. Saw zero difference on the dyno, plug cleanliness, idle or RPM quality. They definitely didn't make tuning any quicker/easier. I wonder why they didn't include any test reports or dyno comparison results?

From the article:
Advantages of Side-Gapping

1. Side-gapping or cutting back the ground electrode exposes more of the spark to the fuel mixture. A full-length ground electrode can block part of the air/fuel mixture from exposure to the spark.
2. Minimizing surface area with a shortened ground electrode allows more heat to flow into the combustion chamber; in certain instances, this may result in needing less firing voltage for spark generation. The reason: Electricity itself doesn't directly ignite the mixture; actually, it's the heat energy generated by electricity that generates the flame. Some of that potential heat energy is lost through reabsorption back into the metal surface of the center and ground electrodes—so, less surface area, theoretically less lost energy.
3. A shorter ground electrode may reduce the changes of preignition, especially with power-adders including nitrous oxide, superchargers, and turbochargers.
4. A cut-back ground electrode may offer more dome clearance at TDC when installed in older, less efficient, larger-volume, combustion chambers that are coupled with domed pistons.

 

[66Satellite47]

I tried the "cut back" trick back i the early/mid '80's with an MSD 404BC which had lots of spark capacity, not sure it made any real difference. Also used the NGK V plugs, Autolite race plugs. Autolite with the short ground seemed to work real good, the NGK were too. 440 iron head 12.0 CR, 7000 RPM.

 

[Wietse]

Thx for your comments gents.
As you described Beanhead, there are potentials that should help but there are no dyno tests or so on the web as far as i've seen to understate the improvements.
I was wondering now, as i've just ordered a new set of spark plugs to modify the old ones and give it a try.
I am using NGK XR5 (3332) plugs on my 440 with 906 heads and 10.5 cr.

 

[twecomm]

Then there is E3 spark plugs that have a slightly different design. At 3:35 into the video, they actually show the burn in a test chamber. Graphic demonstration on burn created by the E3 vs. conventional plug design.

 

[Wietse]

It is a bit "home made" versus "marketing" with side gapping and these E3 plugs.
I was under the impression that this was a secret improvement thing that a lot of people here would be using but it seems not.

Think i will try and cut up my old plugs and see if there is any changes, not expecting any "power gains" but hoping for a improvement in idle or cruise quality.

 

[MoparLeo]

Just short plug life.

 

[Wietse]

Just short plug life.

Yes it does shorten the plug life, but then again $30-35 once a year on spark plugs is not much to think about if it does make some improvements.

I've "side gapped" my old plugs, hopefully tomorrow i can go for a drive and will see if there is any changes.

 

[mrhemi]

I pulled the "side gapped" plugs out of the 300 cu in 6 in my F150, looked just like these. The .065" + gap was probably more to do with the 90000 miles on them. Still ran ok though.

 

[Bee1971]

Those plugs are rich and maybe oil fouled

What carb and settings

You have oil on the threads and or plug gasket ?

 

[Wietse]

I pulled the "side gapped" plugs out of the 300 cu in 6 in my F150, looked just like these. The .065" + gap was probably more to do with the 90000 miles on them. Still ran ok though.

Yeah, they will wear out fast and on 1 side only now.
But trying on an old set of plugs first, then again $4/plug.
I am still not sure if using any Iridium plugs would be worth it.

Those plugs are rich and maybe oil fouled

I know. Engine runs pig rich. At the moment i am using a Holley Street Avenger 770, i am waiting on an order from Summit with some materials to rebuild my 750 double pumper and try that one again.
I already spend a lot of time on this 770 to run leaner but with no real success.
It needs a rich idle to run decent so the idle screws are quite far open, anything smaller then a .72 primary jet and it will cause a sag when speeding up.

It's not consuming any oil though.

 

[Wietse]

I had a good drive today, must say it seems to start and idle better than before.
I will drive it for some time with these modified plugs and later change to the new spark plugs to see if i can notice any difference.

And in the meantime re-jetted the carb and changed the vacuum secondary spring for a heavy one to lean it out a bit.