The mechanical advance has 2 weights in it. They are different and only one has a spring. They BOTH work, it is just the one with the spring comes in a little later. It gives a "knee" to the advance curve. Also take notice that on the distributer cap the cylinders are not spaced equally apart. This has the effect of varying the advance for certain cylinders. It is very important that you wire the cap exactly to the cylinders as marked on the cap so as to maintain the correct timing for each cylinder. Base timing is mainly there for ease of starting and to minimize emmisions at idle. If you look at the advance curve (mechanical AND vacuum) you will see it advances quickly like most internal combustion engines. For best power and economy you want to try to get as much advance in as quickly as you can. That is of course up to the point BEFORE you get pinging! The problem is that for production motors all of this tends to be on the conservative side so that there is plenty of room to "cheat" and if you want to maximize things you could probably add even more advance. Going with a higher octane fuel will allow even more advance. If you do try this remember you are flirting with disaster. You can burn valves and pistons if you overdo this. In any case more advance is usually better than less. If your mechanical or vacuum advance systems are not functioning you will have poor fuel economy and low power. This is why going to a full engine managment system is so neat. You can change things like base timing and advance "on the fly" from the passanger's seat. Add a knock sensor and the system can run you right up to the edge for maximum performance without the danger of damaging the motor! This is the ticket for any serious performance gains. David Teitelbaum vin 10757 --- In dmcnews@xxxxxxxxxxxxxxx, "content22207" <brobertson@xxxx> wrote: > > > Slight clarification: > > 13 degree BTDC base time is due to the hobbled DeLorean ignition > distributor (one centrifugal counter weight disabled), not PRV engine > design. Exact same engine (B28F) is base timed at 10 degrees in a > Volvo. DeLorean has a flatter advance curve, which requires moving all > sparks closer to cylinder bottom. > > I'm guessing DMC did this for emissions. North American Volvo's used > To address comments privately to the moderating team, please address: moderators@xxxxxxxxxxx For more info on the list, tech articles, cars for sale see www.dmcnews.com To search the archives or view files, log in at http://groups.yahoo.com/group/dmcnews Yahoo! Groups Links <*> To visit your group on the web, go to: http://groups.yahoo.com/group/dmcnews/ <*> To unsubscribe from this group, send an email to: dmcnews-unsubscribe@xxxxxxxxxxxxxxx <*> Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/