[Fot] richer needles than the RH

[Stephen Myers]

You cannot use any reading that you saw on your plugs after a race as any basis for changes.  Your plugs can change in such a quick time that without a dyno your readings will mean almost nothing.  The correct way to read plugs at a track if you have to is to make a few laps and then accelerate hard out on a lap and on the last corner and shut the engine down when you let off to coast into the pit lane to do your readings.  Running your engine any amount of time between full load on your engine and your reading will give you false readings.  Your racing engine requires such small adjustments and tolerances than what “reading plugs” is intended for with street cars that using this method is not very useful compared to other methods such as a proper gas analyzer.

I will add that using a dyno logging air fuel ratio you can also view how the profile of your needle is working and adjust needles only where needed based on piston heights instead of basing your needle choices on overall lean/richness.

-Steve


> On Jun 28, 2017, at 10:32 PM, Henry Morrison via Fot <fot at autox.team.net> wrote:
> 
> Thanks for your replies.  I usually check my plugs in the reflection in my knockoffs from the light from a Coleman lantern. My current needle supplier has not suggested anything other than the RH, usually he has a plethora of suggestions. 
> 
> I didn't build the engine but it has an advertised compression ratio north of 10:1.  It has an Isky cam with the number at home in the file.  Previous owner ran an couple of races at altitude (+- 5000 ft.) and one Kastner Cup down at about 800 ft..................................................................................................................................................................................with the SM needles.
> 
> I plopped the RH needles in at Blackhawk and it still looked lean.  Hopefully I haven't done any damage.
> 
> Bruce pulled well up above 5000 revs,  I didn't dare venture up to 6000, but he felt like he would go there no problem. 
> 
> I'll be at Road America with at least as many needles as spare spokes......................
> 
> Cheers, Henry Morrison, Albuquerque, NM  
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