I have been running a .035 spark plug gap with the MSD ignition that was attached to my Holley HP EFI unit, and now have the (8) Holley Smart Coils...should I increase the spark plug gap now?

And if so, what gap should I go with? I have the CNP on both cars now, one on my 440 Wedge engine, and one on my 605 Gen II Hemi. I have 11.5:1 compression on the 440, and 11:1 on the Hemi.

Thank you for any suggestions.

Mark

I run 035 on my HP with the GM coils on my SB..
gust a little less compression

I would recommend .028 to .030.
Inductive spark and CD spark have to be looked at differently.
With inductive spark, the power that doesn’t get used during spark initiation gets discharged in duration.

Rick.. quick question.. what was the name of
the holley that I can ask a question
thanks.. this is a new puter and I didnt
transfer all that stuff
thanks

Im not understanding your question. I think some words are missing😯

Holley efi forum?

The Holley site on line that has the one guy
that answers most of the EFI questions.. you
have been on that site many times.. if you have
a problem he usually knows of it
thanks

Danny

I dont know the guys name but I want to ask
something on the HP unit
thanks

Danny is the guy that handles most of the questions there. Ijust posted there this morning regarding a post by andyf.

Can you give me the web site name.. I want to
do some reading on the HP

Thanks Mike for your response, however I am using the Holley Smart Coils, and they are supposed to be a hotter spark because of one Spark per cylinder. Right?

That is why I was asking about Gap size.

Mark

On the GM coils I run 1 spark per cyl.. I dont
know if the smart coils are hotter or not

The smart coils are inductive. Typical high hp engines using them set plug gap @.018- .022.
Spark duration is the benefit.

This is a neat video of a spark trail. CDI first, then inductive added...
https://youtu.be/2GGIgXwSPdo

Hi Trendz, Watched the video...the MSD is the long duration spark, and the Inductive is the short spark.

So, they show the inductive first, then the MSD spark. Correct?

If the program in the HP is set for 4.5 MS of charge cycle for spark, would that not be much stronger of a spark?

Since the Holley Smart coils are not MSD (multiple spark discharge), then the video you show is immaterial. Right?

Besides the MSD unit is only MSD under a certain RPM?

Thank, Mark

I haven't looked at this issue much but it seems like the factory uses some fairly wide plug gaps on the newer CNP engines. In the range of 0.040 or so on a few engines that I looked at. Maybe it all depends on the engine and the ignition system?

Hi Andy, I am using 8 of the Holley Smart coils...that alone should give me very good spark, I think. Also, since there are 8 coils, each coil has a longer time period to charge and store energy per fire.

I Thought the LS engines spark plugs were set at .045, but that, might not be correct?

Mark

No just the opposite. The CDI is the short duration, high energy start. The inductive sparkis the long duration trail.
This is why MSD has multiple sparks below 3000 rpm. The short duration CDI spark would not burn up themixture fully at low rpms.

As far as plug gap, you can run it wide... but you end up with a much shorter spark duration doing so. The wider the gap, the more you stress the coil/ wires/ plugs.
The Ign1 coils are capable of burning holes through some spark plug insulators. Much better to take it easy on the hard parts and turn the energy into duration.