Re: [DML] Clarification: DeLorean Spark Advance
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Re: [DML] Clarification: DeLorean Spark Advance


Could you provide us with a little more detail on your modification? I would definitely like to try that here. Especially as my 1981 car is exempt from Massachusetts emissions inspection.

  ----- Original Message ----- 
  From: content22207 
  To: dmcnews@xxxxxxxxxxxxxxx 
  Sent: Wednesday, August 22, 2007 1:41 AM
  Subject: [DML] Clarification: DeLorean Spark Advance

  Before I get flamed out of existence, let me clarify DeLorean spark
  advance relative to its Volvo counterpart:

  The DeLorean ignition distributor has one centrifugal counterweight
  disabled. Otherwise it appears to be identical to Volvo F Series
  (mechanical advance spec's are one half Volvo's).

  To compensate, DeLo runs full manifold vacuum to the spark advance
  diaphragm. Of course this makes the engine extremely difficult to
  start and risks predetonation when the throttle plates are closed (max
  vacuum), so they stick a microswitch under the throttle plate linkage
  to operate a solenoid that cuts off vacuum spark advance when the
  plates are closed.

  And of course base ignition time is advanced 3 degrees before Volvo.

  In contrast, Volvo runs ported vacuum (same port as the purge signal
  to the charcoal canister) to the spark advance diaphragm. No
  microswitch or solenoid. Not only is this a much cleaner and simpler
  installation, but by virtue of having both counterweights active it
  actually yields more spark advance at higher RPM's (minimum vacuum),
  which is when you need it most.

  The whole DeLorean setup appears designed to maximize fuel burn at low
  RPM's, such as stuck in California traffic, not yield better performance.

  As I understand it the DeLorean distributor does have its missing
  counterwight inside -- it just isn't connected to the rotor hub. If
  the missing spring were replaced it should perform like a Volvo
  distributor (DeLo mechanical spec's are one half Volvo's). In such a
  state vacuum advance could then be attached directly to one of the
  throttle plate ports rather than the driver's intake rail. Otherwise,
  owners are stuck with DMC's rather convoluted setup.

  FWIW: I'm running a fully functional distributor and find performance
  to be quite invigorating.

  Bill Robertson


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