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Re: Thanks for the advice- sputtering 74 MGB

To: MG List <mgs@autox.team.net>
Subject: Re: Thanks for the advice- sputtering 74 MGB
From: Max Heim <max_heim@sbcglobal.net>
Date: Fri, 06 Jan 2006 11:26:33 -0800
Makes me glad I bought an Allison, then. My 25D was severely worn at the
time, and wouldn't maintain a decent point gap. The optical system has been
absolutely trouble-free for what must be 15 years now. It couldn't be
simpler -- an LED, a light sensor, and a black plastic disc with 4 slots in
it. I suppose the lack of a visible external box is the only reason the
Pertronix has become so popular -- it certainly doesn't sound more reliable,
and it is (was) more expensive.


--

Max Heim
'66 MGB GHN3L76149
If you're near Mountain View, CA,
it's the primer red one with chrome wires


on 1/6/06 10:46 AM, Dodd, Kelvin at doddk@mossmotors.com wrote:

> Max:
> 
> The Pertronix system does seem to be sensitive to shaft wear.  The air
> gap is critical and that was one of the reasons why the very early kits
> had problems.  The later small package kits are much better, but
> severely worn bushings still will cause problems.
> 
> The original Pertronix units were designed to replace the electronics in
> the 45D units.  These early units were extremely good with very, very
> few failures.  This was probably due to the lack of bushing wear in
> these distributors.  When the Pertronx unit was first installed in the
> 25D the failure rate was unacceptable, until the new package was
> designed.  
> 
> 
> One other note.  Installing an electronic trigger in a 25D distributor
> will tend to reduce cap and rotor life.  The 25D is much more prone to
> internal arcing than the 45D, so make sure that the cap, rotor, wires
> and plug gap are all to spec.
> 
> It still beats grubbing around the engine compartment and dealing with
> point contact corrosion if the car sits for a while.  I'll let you
> imagine the nasty noises I made the last time I tried to back my MGB
> race car out of the trailer and found the points no longer had
> continuity.  Luckily I hadn't thrown away my points file.
> 
> 
> Kelvin.
> 
> 
> 
> 
> 
> -----Original Message-----
> From: owner-mgs@autox.team.net [mailto:owner-mgs@autox.team.net] On
> Behalf Of Max Heim
> Sent: Friday, January 06, 2006 10:06 AM
> To: MG List
> Subject: Re: Thanks for the advice- sputtering 74 MGB
> 
> Maybe it doesn't work with the Pertronix system, but the
> optically-triggered
> systems like Allison or Crane seem to be very tolerant of distributor
> wobble. It makes sense, since they are sensing a slot (say that 3 times
> fast), so side-to-side play has no effect on timing.




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