Different plug gap values in same engine at same time ??

[vpls4]

I'd like to know if more than one person has ever had different plug gaps in their engine at the same time, on purpose not from wear?

Something to the effect of.. having a few at .026 but still seeing activity/correction on a couple cyl's so gapping only those down to .025

What's your experience with this? Did you end up later just gapping them all down to the same size? Just seems weird having diff burn rates due to diff gaps.

I'm asking this because my mechanic said neither he nor some person at giac has heard of having dif gaps at same time.

PS There is absolutely nothing on the internet about this, some interesting side gap stuff, spent well over an hour looking, nor on here except a thread where I'd asked the question w/o much traction...would really like to hear if more people than just the one person that answered in DP thread have done this since my mechanic saying what he said and finding nothing on the net.

Thanks,
Bill

[theweebabyseamus]

Like adapting gap to, for example, timing pull values on individual cylinders?

[Dr GP]

I think the specs are .30, although I remember reading someone suggest that .28 might work better.

[eurotic]

I am currently running different gaps on one bank trying to determine some knock pull I was seeing. I cleaned and gapped the 3 plugs to .026. I saw knock pull decrease so I think it's just time for new plugs and coils...which I have waiting to go in.

Normally I would make them all the same if it weren't for testing.

[vpls4]

Like adapting gap to, for example, timing pull values on individual cylinders?

I'm seeing up to -6 & -7s on cyl 3,4,6 using IGA_AD_1_KNK_* the other three are at 0's, so I'm wondering if it's best practice to adjust just those w/activity or make them all .025

[cspcrx]

Try it and see. I do not see how it can hurt the motor at all.

Back in the day we used to index spark plugs to orientate them to the cumbustion chamber. This meant some plugs extended further into the cylinder than others. You would think that would change the performance in other ways, or at least I did. When your looking for every ounce of hp out of a motor restricted by class rules you try anything.

Looking forward to seeing what your logs show.

[saxon]

the goal of gapping each cylinder separetely is to make sure there is no knock in any cylinders which should - more timing/more power

[vpls4]

Thanks everybody for the input...looks like I will just adjust the 3,4,6 which show activity.
What's interesting is that according to firing order 1-4-3-6-2-5 the cyl's showing activity are all in a row. Hopefully more top end after adjusting those three