View single post by pbahr
 Posted: 04-06-2007 07:40 pm
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Joined: 04-15-2005
Location: Phoenixville, Pennsylvania USA
Posts: 202
Greg etal,

Well, as I've said earlier, it took me a very long time to sort out the Weber jetting.......   Reminder that YELODOG is a 2.2l, with lots of other stuff, and over 200 hp engine.

Here's the data that I dug out of my files:
  • Weber info.
    • Main Venturi:  36 mm
    • Aux Venturi:  4.5 mm
    • Main Jet:  135 F3 180
    • Idle Jet:  50F9
    • Start Jet:  60F5
    • Accel Pump Jet:  45
  • Spark Plug.  (I have Electromotive Crank-Fire Ignition)
    • 0.038 gap
    • Autolite #64
  • Timing.
    • Idle:  5 deg
    • 3000: 27 deg
    • 7000: 29 deg
  • Emissions.
    • HC:  1250
    • CO2:  6.5
    • NO:  20
    • CO:  8
    • O2:  6
  • Gas Mileage.
    • Highway:  21.1 mpg
    • On track:  16-18 mpg
There is a minor acceleration hic-up during city driving at about 3000 rpm a I recall.  BUT, I'm quite satisfied.  You kinda learn to drive around it.  No major stumbles though, just a slight glitch, even when accelerating on highway (like slow gas pedal pressure going from steady 60 mph to 70).  It is that point where the mixture transitions from the Idle Jets to the Mains.  Perhaps a change in the Accelerator Pump Jet might help ?  The Delortos have a third circuit to cover this range, so they are alledgedly smoother.

I have a set of 40 mm Main Venturi that I might try - but it's such a pain-in-the-**s to do this stuff, that I probably will never muster up the energy to start !  Guess if I had an engine gas analyzer, I might try it, but , I don't have one.

If I go any leaner on the Idle Jets, there is major stumble.  If I go richer, I get plug fouling.  The 50F9 does the trick for me.  HC with the next richer Idle Jet were over 2000.  Only remaining problem is that #4 cylinder runs a bit wetter and darker than the other three, but this car has always done that - I've heard similiar from other owners.

BTW, before I get slammed on the cheap spark plugs, I do have a reason:  Consider plugs that have heavy wear.  What does that mean?  It means that there is metal  being lost during sparking (like Electric Discharge Machining).  Well, these very tiny bits of red hot metal enter the cylinder during the spark and help ignite the fuel charge.  Better ignition !  I don't care if I have to change plugs every 2000 miles - who cares anyway?  I think they're about a buck apiece.

Of course, all of my opinions are open to debate and challange by others more knowledgable than I am.................