Thank you, Colin, for that very useful information. Your E-mai taught me quite a few things, and I will definitely keep it for future reference.
How exactly do distributors retard the timing for detonation control? Serge Vidal KR2 "Kilimanjaro Cloud" Paris, France "Colin Rainey" <[email protected]> Envoyé par : [email protected] 12/28/2005 04:01 AM Veuillez répondre à brokerpilot96ta; Veuillez répondre à KRnet Remis le : 12/28/2005 03:59 AM Pour : [email protected] cc : (ccc : Serge VIDAL/DNSA/SAGEM) Objet : KR> Corvair Ignition Serge and Dene I do not argue that your ignition system is simple and reliable. I work on those style ignition systems everyday. Virtually all new cars have a crank and cam trigger magnetic pickup system on them, one way or the other. I have not seen a distributor in a vehicle in a few years now. Only one problem that I see is, no spark retard system built in. ALL modern ignition systems operate with the computer managing the timing based on inputs from several sensors which give the computer engine load and demand information, ie: TPS, MAP, MAF, O2, CTS, ACT, Cam and Crank sensors. Your system works fine as long as the octane of the fuel is properly matched to the engine, AND engine temperatures are kept in a more restrictive range of operation. Remember, motorcycles have tapered walls most of the them that build and relieve compression as they travel up and down. Auto engines do not. When accelerating from cruise rpms, ALL auto engines retard the timing for detonation control, and a dvance as the rpm begins to level back out. In your system, you have fixed timing advance, which is great when initially accelerating, but part throttle acceleration can cause some real problems unless the advance is not "peak" for the engine. Then the engine runs good, but produces less horsepower than is optimal. If timing is set to this optimum setting, then caution with temps and operating conditions must be observed, or detonation is surely a result. This is why aviation engines must use a richer than required fuel mixture to assist in cooling and detonation protection. To extract peak power, one must be able to control timing in BOTH directions, and set it accordingly. Hence my comments about those not committed to something else will find it far easier to set the engine up and get the timing correct with the original distributor, just rebuilt, and updated with electronic pickup instead of points. Adjustments are much easier, and base timing can be set and adjus ted as necessary to fine tune for a particular application. The ignition system process is known in the auto repair world as "Waste Fire Ignition" where the coil fires companion cylinders at the same time, one on compression stroke the other on exhaust. This also does a small part in helping clean the emissions, getting a second chance to ignite the unburned fuel prior to leaving the cylinder. It simplifies the timing curve that must be programmed into the PCM and eliminates parts count. Down side is if a plug wire goes bad, it will go to ground somewhere else and if it can't, it will burn out the coil. Secondly, Dene you were WRONG when you said a 5 cyl can just run one half of a coil for the odd cylinder! This is a big NO NO with this style system. The coil is powered at only one set of terminals, power and ground. Therefore, you MUST have two plugs wires going to two plugs, PROPERLY GROUNDED AS IN INSTALLED in order to not damage this system. Failure to do so will result in the coil being damaged! These coils also fire much hotter in KV then older coils, so plugs need to be of newer design, RFI for noise cancellation, and gaps adjusted appropriately for the compression ratio, ignition. I am starting with .035 gap, but I will also try a set gapped at .045 since I am using a hotter late model coil, and electronic pickup, and no ballast resistor in my power lead to the coil. My electronic ignition does not require a ballast resistor, so I can eliminate one more point of failure, common to the old ignition system. Fly what you are comfortable with and feel safe behind. But as I have said before, if you don't fully understand a system on your plane, learn about it, and get to know it, or replace it something you do know. Otherwise you are flying in the dark, or kinda with blindfolds. My remarks about sticking with the stock system, come from spending time modifying our KR to a better engine with a known quantity, and IT STILL IS TAKING TOO LONG. The more mods the longer the road... Colin Rainey [email protected] _______________________________________ Search the KRnet Archives at http://www.maddyhome.com/krsrch/index.jsp to UNsubscribe from KRnet, send a message to [email protected] please see other KRnet info at http://www.krnet.org/info.html
