"As we all know"? Bill, you expect too much from some of us ;-) Judging from the way the tech manual is written, it looks to me like they were very concerned with U-S emission controls. A lot of the sentences contain language like "thus reducing hydrocarbon emissions" ... *shrug* Of course, it's entirely possible that they "over-built" things because of worry or some other reason. I'd guess that it's a matter of opinion. I would probably appreciate making things simpler, but that's probably because I'm not a skilled mechanic! I think I have to understand *why* something works (or doesn't) before I go about fiddling with it. Obviously you know what you're doing. For the most part, I don't. :P But I also would like more information on this, please! Come on, group! It's not Mardi Gras everywhere, is it? ;-) Farrar Hudkins #2613 On 2/5/08, content22207 <brobertson@xxxxxxxxxxxx> wrote: > I am corresponding with an owner Re: spark advance. As we all know, > DMC decided to use only one centrifugal counterweight inside its > distributors rather than two (Volvo used two on its imports to the > exact same North American market). To compensate, DMC: > - Bumped base ignition time from 10 to 13 degrees BTDC > - Ran full manifold vacuum rather than ported vacuum to the advance > diaphragm > > This oOf course leads to generally overadvanced ignition, so for > better starting and cold engine performance DMC further: > - Ran its vacuum through a thermactor valve and an idle cutoff > solenoid before the distributor > > My question: Why did DMC find it necessary to reinvent the spark > advance wheel? > > B28F has two centrifugal counterweights, 10 degree base ignition time > (steeper advance curve), and only one vacuum line from a ported barb > under the throttle plates directly to the advance diaphragm. What > could be simpler? > > And again: Volvo imported its setup into the exact same North American > markets, during the exact same time period (1981-1983). If their setup > was good enough for the US government, shouldn't DMC have been able to > use it too? > > BTW: US Volvos also came with a Y pipe and single catalytic converter. > They used Lambda as well. > > More engineering from Dunmurry that causes me to scratch my head. 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/ <*> Your email settings: Individual Email | Traditional <*> To change settings online go to: http://groups.yahoo.com/group/dmcnews/join (Yahoo! ID required) <*> To change settings via email: mailto:dmcnews-digest@xxxxxxxxxxxxxxx mailto:dmcnews-fullfeatured@xxxxxxxxxxxxxxx <*> 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/