.060” with high energy coil.

Define a high energy coil.

We used to find some power on the dyno by playing with plug gap. You gotta remember that there is distributor timing and dynamic timing that is affected by a lot of things. Higher reving engines seemed to like one thing and low end grunt liked something else. Road race engines with wide rev ranges were a compromise as would be street/performance cars. The ignition guys like MSD usually have ok recommendations.

Update...
I reset all the plug gaps and used a penny to get the desired gap. The penny was the closest to 0.60".
The car ran great. I think I could detect an even smoother idle.
I look forward to seeing the mpg and performance after doing this.

I tried it once, seemed to make no difference on my car, and its a lot of work, especially if the engine has headers because the plugs are in and out a lot to get them right.  Maybe on something super high performance its worthwhile, but IME not on a typical street or street/strip engine. 

Oh, there's a difference from getting the gap right, no doubt.  I was referencing plug indexing.  That's where you align the gap in the plug to the intake valve.  The idea is that it starts the burn at the earliest possible moment.  It requires washers to space the plug out whatever is needed so that it lines up.  You mark the plug as to where the gap is and install it, see where the gap ends up, then add washers and try again if it wasn't right.  Wash, rinse, repeat until its right, then do that rigamarole 7 more times. 

I just read an article by NGK on indexing. It was interesting,  but even they seemed to indicate uncertainty in doing it.
Have you guys side gapped plugs? I do know of this, but wondered if it was worth doing. I remember back some years, those fork tipped plugs were all the rage, but hardly hear anything about them now.
Oh and while I was reading up on indexing, I came across some discussion where drag racers and performance guys intentionally run narrower plug gaps. This had me confused as I always thought the wider the gap the better (within reason)

All the fork tipped, ring tipped, etc. plugs are gimmicks.  Smokey Yunick devoted a couple pages in his autobiography to his testing various ignition devices, including flame ignition as opposed to spark ignition.  He was sponsored by Champion at one point and spoke highly of their engineers (not something he did often).  The summation was that a spark is a spark.  Even flame ignition which seemed promising initially turned out the same.  Its much more important when you initiate the burn than how its done.  Some chamber designs can benefit from multiple sparks, especially the less efficient they are.  In the end though, proper heat range in racing was more important than anything else.  Those lean, mean mixtures will melt a stock plug.

In racing most guys I know run regular copper plugs, unless they have forced induction where iridium is preferred because its much less likely to erode.  The gap is always going to depend on your ignition system, and testing. 

Cab4word67 wrote:

.60 wow i have a stock 289 with a 2 bl. just did the pertronics conversion with there flame thrower 40,000 coil I was thinking of going up to .45 but, .60 really???


I've tried wider gaps, indexing, high end plugs and cheap ones at our local 1/8 mile track one sunday afternoon. The butt dyno didn't feel anything or did the timeslips much. The only thing I did notice a few weeks later, was the cheap Champion plug blew the center out, and part of it ended  up in a different cylinder.
Chris

Last edited by red351 (2/05/2020 9:19 AM)

Rudi wrote:

FYI going up in plug gap can effectively retard timing a couple of degrees.

Interesting to know...
I have to say that my car seems to be burning the fuel better since I reset all the plug gaps.