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From: phil@amdcad.UUCP (Phil Ngai)
Newsgroups: net.auto
Subject: Re: eliminating distributors
Message-ID: <498@amdcad.UUCP>
Date: Tue, 8-Jan-85 02:34:32 EST
Article-I.D.: amdcad.498
Posted: Tue Jan  8 02:34:32 1985
Date-Received: Tue, 8-Jan-85 07:50:49 EST
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> I would like to defend the conventional distributor a bit.  First,
> it is a simple and reliable device.  I have NEVER had to replace
> a distributor cap (except one I smashed in an accident), nor have
> I had to replace a rotor.  Shorting is caused either by poor sealing
> in the original manufacture or by some nerd removing the cap (which
> is not necessary with a breakerless ignition).

Distributors do not last forever. When I pulled my cap to dry
it off, I noticed the contacts were quite pitted, and my manual says to
replace it when noticable pitting is present. When you think about it,
spark erosion is inherent in the design. This applies to the rotor too.
You are supposed to pull the cap and inspect it for wear periodically.

> Second, the distributor provides dynamic timing adjustment as well
> as switching the high-voltage ignition pulses.  A centrifugal 
> mechanism advances the timing at high engine speed.  A vacuum advance
> retards the timing under heavy acceleration or when the engine is
> about to stall.  In order to replace these devices, one has add
> transducers and a considerable amount of logic to the ignition system.

I seem to recall some controversy about mechanical vs vacuum advance.
As far as I'm concerned, they are both ugly kludges.
Semiconductors are cheap. We have a saying, "all ICs will cost $5,
unless they are plastic, which are less". The transducers can't be
a big deal either. The presence of modern fuel injection means the
necessary transducers are already there and designs without fuel
injection (but why?) can take advantage of the high production
volume of transducers to get low costs.

> In conclusion, I think that totally electronic ignition systems will
> eventually take over from mechanical.  However, the complexity of the
> system is increased, albeit encapsulated in some multi-hundred 
> dollar "control module".  That control module will require no 
> adjustment during its lifetime.  But when it fails, don't expect
> to be able to dry it off with a rag, or to file it down a bit, or
> do anything else other than to call a tow truck and wait while your
> local garage orders a new one.

Yeah, my timing belt broke and I had to call a tow truck. So that
experience is not unique. I claim that an electronic distributor will
not fail as often as the mechanical kind and is a step forward.
In the last paragraph I explained why I do not expect the electronics
to add much to the cost of the product.

I guess I shouldn't mention another pipe dream of mine: electronically
controlled intake and exhaust valves... You want a new camshaft
profile, get out your computer terminal...
-- 
 AMD assumes no responsibility for anything I may say here.

 Phil Ngai (408) 749-5790
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