Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Posting-Version: version B 2.10.2 9/18/84; site amdcad.UUCP Path: utzoo!watmath!clyde!burl!ulysses!mhuxr!ihnp4!amdcad!phil 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 References: <458@amdcad.UUCP> <6845@watdaisy.UUCP> Distribution: net Organization: AMDCAD, Sunnyvale, CA Lines: 53 > 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 UUCP: {ucbvax,decwrl,ihnp4,allegra}!amdcad!phil ARPA: amdcad!phil@decwrl.ARPA