Ferrari Mailing List: Re: Spark plug reading?

[LarryT (l02turner]

Hi Peter,
   I have no idea what your knowledge of Weber operation is, so excuse me 
if this is something you already know.   The Webers run on the Idle jets 90% 
of the time.  Until the pedal linkage reaches the point where they start to 
engage the acceleration pumps, the Idle Jets are in control.  Once the 
Acceleration Jets are engaged the Main Jets are brought into play.   It may 
seem odd, but you can be running near redline and still be on the Idle Jets.

   So, as you can see, the Idle Jets are critical for not only good 
running, but also for economical running as well - even though that may not 
be your primary goal.

   When I tuned my Webers I ended up trying 3 or 4 sets of Idle Jets as I 
tried to zero in on the best jets.

   There are some mathmatical formulas for calculating the sizes of the 
jets and venturi's - I'll dig them out and send them along - unless you 
don't need them?

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: Thursday, October 04, 2007 7:03 PM
Subject: Re: [Ferrari] Spark plug reading?


> Thanks, Larry....but I had it on a dyno to check the full throttle stuff 
> and
> ended up with 135 mains.
>
> And this....
>
> http://www.pless.com.au/cars/gt4/rebuild/images/308dyno.JPG
>
> I'm getting a portable analyser in the next few days, so I'll be able to
> check what the actual mixture on cruise is.
>
> It was 12.8:1 with the .55 idle jets...but I didn't get to fiddle with 
> those
> while I was on the dyno.
>
> -----Original Message-----
> From: LarryT [mailto:l02turner [at] comcast.net]
> Sent: Friday, 5 October 2007 2:54 AM
> To: Peter Pless
> Cc: 'The FerrariList'
> Subject: Re: [Ferrari] Spark plug reading?
>
> Hi Peter,
>    They *do* look good.  My only concern would be driving hard.   50 seems
> a touch lean to me but I'm no expert.
>
>    Perhaps a 20-30 minute run with rpm's covering the range from idle to
> redline.   But be careful with temps, especially at WOT - too lean at full
> throttle can cause high temps on pistons tops.  Would hate to hear you
> burned a hole in a piston.
> \
>    I know some say when you examine SPs you;re seeing only what happened
> immediatley before the engine was stopped - but I believe it takes a 
> little
> time to get a SP to change color/texture a meaningful amount.
>
>    Good luck -
> 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: Thursday, October 04, 2007 11:31 AM
> Subject: Re: [Ferrari] Spark plug reading?
>
>
> > http://www.fcavic.com.au//308/index3.htm
> >
> > I installed .50 idle jets in my 308 and cut the engine whilst doing a
> > light
> > cruise.
> >
> > Haven't stuck the analyser in yet, but this looked pretty good to me.
> >
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> > 8:59 AM
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