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On 3 Nov 2002, Jim Adney replied: > > it read about 500ppm hydrocarbons on the emmissions test. He said > > that was a bit high but nothing to worry about. > What is the spec here? HCs would be high if it was running rich. I don't know what the spec is but a year ago the HCs were much higher and the tester said it was because it was running too lean!? HCs get high because the fuel isn't burning properly don't they? I certainly can't wind in the idle jet at the moment without the engine starting to miss and hunt. Perhaps I have more wear in the engine than I want to acknowlege. I know I've a bit lower compression on 3 than the others. On the other hand, if I increased the advance, the RPMs would increase, so I could back off the Idle screw, and maybe wind in the idle jet screw a bit which would mean I would use less fuel at idle and maybe sort things out? I read some advice on another website for MG cars that the advance figures were only applicable on a new car and that as the car aged, so the advance should be taylored to the specific car by trial and error- increasing the advance until it started knocking, then backing it off till it just stopped knocking. Is this wise with a VW? > > When I bought it it was set to about> > 20deg> > adv at idle. > You SHOULD check the vacuum> and mechanical advance mechanisms to make sure that they are BOTH> working smoothly. The vacuum advances sometimes die and they are there> to improve gas mileage. The mechanical advance mechanism often gets> rusty and sticks, giving reduced power and awful gas mileage. I only recently overhauled the dist- the mech advance seemed free and I cleaned and oiled it. The vac advance is working OK. However, with my timing light when I was setting up the pertronix, I could see that the advance wasn't smooth- there were pronounced steps in it. I guess I'll have to pull it apart again:-( > Extra advance will actually make the coil run hotter, but that's with the> std> ignition. It may not make any difference at all to the Pertronics. In> general,> the dwell to shoot for is 45-50 deg. Duh! Of course it will- I didn't think that one through properly- more dwell=more time passing current therefore hotter. Oh well- I don't think the dwell is settable so it must be OK. Thanks for the input Jim, Mark Seaton '73 TA London ------------------------------------------------ To unsubscribe, E-mail to: <type3-off@vwtype3.org> For more help, see http://vwtype3.org/list/