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Join Date: May 2006
Location: dorset england
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sc vacuum
what does the vucuum curve look like for the sc, ie the vacuum condition with incresing revs??
ta Gordon |
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05-19-2010, 05:39 AM
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Location: London Ont Canada
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manifold vacuum is primarily a function of throttle opening and load not rpms
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1980 911 SC 3.6 coupe sold 1995 993 coupe 1966 Mustang Shelby clone 1964 Corvair Spyder Turbo gone 2012 Boss 302 |
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05-19-2010, 06:17 AM
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Quote:
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05-19-2010, 07:06 AM
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Senior Advisor
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Vacuum advance(spark occuring sooner) in a SC affectes the distributor. And it varries on load, idle, part throttle, wide open throttle, ect. In other words there is a range and depending what the throttle is doing, vacuum will be doing that. (don't worry what it all means). Sounds like the distributor advance is ot moving under partal load. Check that it does in fact move with a timing light. And check that timing is set to factory specs. (both mechanical advance and vacuum advance/retard). Check all that and get back to us. you might have to rebuld the distributor if it's not moving or replace the vacuum canister on the dissy. Start with that.
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05-19-2010, 01:48 PM
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i fear that the vacuum canister is shot, i cleaned the dizzie out today as per the excellent Gunter thread on here, it is now looking great and has good mech advance.
what i am asking is, i s there a curve that vac should follow as revs increase all other things being equal, like a distributor curle or the fuel pressure curve??? |
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05-19-2010, 01:56 PM
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Ahhhh I did see one from the Porsche workshop manual. See if you can find one.
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05-19-2010, 02:07 PM
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i have looked in my bentley, nowt
on the net , now so I would be ever so grateful Gordon |
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05-19-2010, 02:10 PM
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Not in the bentley, in the Porsche service manual series.
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05-19-2010, 02:14 PM
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There may be a chart showing degrees of vac advance with increasing vac . The ROW model only uses vac advance while the US emission model uses a vac advance and a vac retard on the distributor. There is a chance you have connected your advance unit to the throttle port for the retard unit. It shuts off the vac supply to the retard portion just above idle or the vac switches from one port to the other . I would use a timing light and confirm that your vac unit is working. You should see something like 10 deg. ign advance and retard when you disconnect the hose.
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1980 911 SC 3.6 coupe sold 1995 993 coupe 1966 Mustang Shelby clone 1964 Corvair Spyder Turbo gone 2012 Boss 302 |
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05-19-2010, 02:18 PM
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ok I will look or it but i have not seen one, the manual that is not the chart!!!
so if anyone has one can they scan it foe me? Gordon |
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05-19-2010, 02:18 PM
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