Ferrari Mailing List: Re: Spark plug reading?

[Dave Handa (dave]

If it is the same as USA cars, it would be 125 mains, 220 AC and 50 (?) idle



-----Original Message-----
From: LarryT [mailto:l02turner [at] comcast.net] 
Sent: Wednesday, August 15, 2007 5:48 PM
To: dave [at] davehanda.com
Cc: The FerrariList
Subject: Re: [Ferrari] Spark plug reading?

Hi Peter,
Sorry if this has been covered - haven't read all the posts (sorry) - has 
your distributor curve profile been checked?  Weights stick, springs lose 
tension and gradually the distributor stops performing as it should.

If you have reason to suspect the jet inventory may be off a bit I can check

my reference material and see what was originally spec'd for your 308GT4 - 
if you'll provide the year altho the year may not matter -.

You comment about checking the exhaust gas to see how close the tuning is 
can really pinpoint the changes needed, if any.

Also, I have several tuning procedures (for 911s but all Webers are very 
similar - especially the DCOEs and IDAs)  - they can be found at 
http://members.rennlist.com/webercarbs
I also have some formulas for calculating the main jets and main venturi 
sizes.

Take care --

Larry T (67 MGB, 74 911, 78 240D, 91 300D)
www.youroil.net for Oil Analysis and Weber Parts
Test Results http://members.rennlist.com/oil
PORSCHE POSTERS!  youroil.net
Weber Carb Info http://members.rennlist.com/webercarbs
.

----- Original Message ----- 
From: "Peter Pless" <ferrarilist [at] pless.com.au>
To: "Larry Turner" <l02turner [at] comcast.net>
Cc: "'The FerrariList'" <ferrari [at] ferrarilist.com>
Sent: Wednesday, August 15, 2007 8:29 PM
Subject: Re: [Ferrari] Spark plug reading?


> 130 mains (125s drilled out) and I THINK 220 AC but I'll have to double
> check that.
>
> When I pull the plug out later, I'll confirm the type as well.
>
> It's all interesting stuff.
>
> One of my mechanics has a mobile gas analyzer. I guess that would make
> things much easier.
>
> -----Original Message-----
> From: Dave Handa [mailto:dave [at] davehanda.com]
> Sent: Thursday, 16 August 2007 9:31 AM
> To: 'Peter Pless'
> Cc: 'The FerrariList'
> Subject: RE: [Ferrari] Spark plug reading?
>
> What are your main and AC jets?  What plug are you using and what heat
> range?
>
>
>
> -----Original Message-----
> From: Peter Pless [mailto:ferrarilist [at] pless.com.au]
> Sent: Wednesday, August 15, 2007 4:02 PM
> To: dave [at] davehanda.com
> Cc: 'The FerrariList'
> Subject: Re: [Ferrari] Spark plug reading?
>
> Gee...look at all the information I didn't give.
>
> Ok..so it's originally a twin distributor car but now has 10:1 
> compression,
> euro GTB cams, no smog equipment and programmable pointless electronic
> ignition (BSM)<---which is excellent btw, starting at 12 deg btdc at idle
> and max total advance of 34 deg btdc
>
> I only pulled the one plug from the one bank.
>
> I will give it another go under different conditions. BUT....i'll do it
> after cruising, not going flat out at this stage. I'm interested in 
> getting
> low throttle/low engine speed stuff right too. I'm running 55 idle jets.
>
> Hopefully, I can do that later today.
>
> -----Original Message-----
> From: Jason Polzer [mailto:jason [at] internethosting.com]
> Sent: Thursday, 16 August 2007 3:20 AM
> To: Peter Pless
> Cc: 'The FerrariList'
> Subject: Re: [Ferrari] Spark plug reading?
>
>
>   I agree no idle before reading plugs.  I remember in 1/4 mile racing
>   cutting my engine at the same time as lifting my foot while crossing
>   the finish line.  And then trying to make the turn around quickly and
>   safely enough to coast back to the pits and pull a few plugs.
>   Jason
>   Rick Lindsay wrote:
>
> Hey Peter,
>   Everyone and his brother will have opinions on this issue but I'll add
> mine.
>
>   First of all, a plug-cut should only be done (read:
> only be interpreted) from plugs that have not been subjected to recent 
> idle.
> That is, the technique
> says: Go for a spirited drive and at the last second of that drive, cut 
> the
> engine WITHOUT allowing it to idle - not even rolling into the garage. 
> The
> carbon build-up comes from idleing and that can preclude an honest read of
> the plug.  This site has a good write-up on the idea:
>
> [1]http://www.centuryperformance.com/spark.asp
>
>   Don't forget to go to page 2 where there are more pictures.
>
>   Your picture shows an insulator that is about the right color, perhaps a
> little too cool (read: it isn't staying hot enough to burn off deposits).
> The ground electrode color isn't too bad either.  Still, I would expect 
> the
> whole thing to be a dusty tan color if everything was balanced properly.
> The black carbon around the base of the plug is not too much of an issue
> with me.  It says that you may be running a little rich.  Still, a little
> rich 11:1 to 12:1 is a more powerful charge mixture than the perfect 
> 14.7:1
> ratio.  We must also remember that a leaner mixture burns hotter.
> Conversly, rich mixtures burn cooler.
> Therefore, air-fuel ratio or 'mixture' must be matched to the plug heat
> range.
>   Then there's compression ratio.  That too changes burn rates.  Higher
> pressure charge is harder to ignite therefore, a stronger ignition is
> required.
> Ferrari ignitions are arc welders so if you're running a stock ignition,
> you're probebly strong enough (assuming it is in good health).
>
>   Quick question: Do all of the plugs look similar or is one bank
> different; or one plug different?
>
>   Okay, that's just some stuff to ponder.  From this and someone else's
> post with the 'right' answer, you'll get the engine dialed in.
>
> regards,
>
> rick
> '79 308GTB
> --- Peter Pless [2]<ferrarilist [at] pless.com.au> wrote:
>
>
>
> Does anyone know what this means?
>
> [3]http://www.pless.com.au/308plug.jpg
>
> It's from my newly rebuilt 308GT4 engine. 10:1 compression running on
> unleaded fuel.
>
> Programmable ignition gives it lots of advance.
>
> When the plug was pulled, I'd come back from quite a long drive, but the
> last bit of it consisted of traffic and plenty  of idle speed stuff.
>
> What's with the carbon on it already? Engine's only done 600 miles....and
> I've been nursing it.
>
> TIA
>
> Peter
>
>
>
>
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> References
>
>   1. http://www.centuryperformance.com/spark.asp
>   2. mailto:ferrarilist [at] pless.com.au
>   3. http://www.pless.com.au/308plug.jpg
>   4.
> http://lists.ferrarilist.com/mailman/options/ferrari/rolindsay%40yahoo.com
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