Re: [AMC-list] spark lead question for tuning experts like Nick Alfano...

[tom jennings <tomj@xxxxxxx>]

OK, thanks Nick! What you say makes sense to me. Yeah, is a few HP worth
running on the ragged edge on the street? Probably not. So a few extra
degrees might gain very few percent increase at the risk of destruction. I
get your point -- racing with a tuned and instrumented motor, 1% is a good
gamble. Thanks, I'll stay away from the cliff's edge!

I've always wanted to tune spark with a pyrometer, it seems like the right
way to set timing.

Thanks again!





On Tue, Oct 20, 2009 at 20:47, Nick ALFANO <71amx@xxxxxxxxxxxxx> wrote:

> Tom,
>
> I am blushing at the accolades but I don't claim to be an expert.
>
> On a stock engine, the returns are not going to be that noticeable when you
> are talking 34 degree Vs 36.  Someone said NASCAR guys say they run best
> just before the blow.  That is pretty much true (ever notice your grass
> trimmer or leaf blower seems to get a boost in power just before it runs out
> of gas).  The most power your engine is going to produce is going to be as
> lean as possible with the most timing it will take before it explodes.
> Basically, the more heat you can produce in the combustion chamber, the more
> power you will be creating.  This also means the closer you are to a melt
> down.  The problem with detonation in a stock engine is most often it is
> going to happen when the engine is under load and doesn't have enough power
> to work through it quickly.  Every revolution under this condition until it
> moves into an RPM where it is making power more freely, especially with cast
> pistons, the closer you are to disaster.  Don't
>  chance it with cast pistons.  The difference in 1 or 2 degrees is not
> going to be worth much.  If at 36 degrees of total timing you have
> detonation, back it off a degree at a time or throw more fuel at it until it
> goes away (slight detonation is hard to hear with headers and dual
> exhaust).  The balance between fuel and timing is key to hp and hard to
> achieve without some sort of monitor like a dyno with sensors looking at the
> fuel/air as well as power graph, blips in the chart that might indicate
> detonation, fuel consumption and or exhaust temps across the power band.  I
> have seen engines where all cylinders look great except one where the
> exhaust temps were 100 degree more than the others telling me that hole
> wasn't getting at much fuel as the others.  My suggestion to you for a some
> what stock engine on the street is, find your spot just before detonation
> while getting a nice read on the fuel mixture by your plugs a little towards
> the lean
>  side.  Run that tune only when racing.  For the street, back it off a
> degree or two more and not as lean for normal street driving.  The
> difference is only going to be a few hp that you most likely wont even
> feel.  The flip side is running on the edge, it only takes one tank of
> bad gas or a hot day to push you towards a melt down that will be costly for
> what, maybe 5hp.  Not worth it.
> .
>
> Good luck
>
> Nick
>  Alfano Performance
> 4849-76 st.
> Kenosha, WI. 53142
> 262-308-1302
> 262-942-8271 after 6pm central and weekends
>
>
> Message: 6
> Date: Mon, 19 Oct 2009 21:30:07 -0700
> From: tom jennings <tomj@xxxxxxx>
> To: "AMC, Rambler, Nash, Jeep and family" <amc-list@xxxxxxxxxxxx>
> Subject: [AMC-list] spark lead question for tuning experts like Nick
>     Alfano...
> Message-ID:
>     <c81e13650910192130x47686fbt606221cdfbb4b80b@xxxxxxxxxxxxxx>
> Content-Type: text/plain; charset="iso-8859-1"
>
> Someone with dyno experience ought to know this stuff by the seat of their
> pants, me I'm stabbing in the dark...
>
> When you have a motor dialed in, just how sensitive is it to ignition lead
> timing when it's under heavy load? In other words, if you have the timing
> dialed in reasonably close, how many degrees away is detonation? How much
> power is lost is it's retarded another degree or two or three?
>
> I know it will vary with combustion chamber and compression and a whole
> slew
> of factors. But for "sort of stock" or stock motors, how touchy is maximum
> ignition timing, power-wise?
>
> Bottom line is, how close to detonation should one push timing before it's
> a
> waste of time?
>
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