My engine builder asked me this, how does the 850 ignition advance and retard work?n As the dizzy and rotor arm is bolted to the engine, how does it fire at x amount of degrees?
My engine builder asked me this, how does the 850 ignition advance and retard work?n As the dizzy and rotor arm is bolted to the engine, how does it fire at x amount of degrees?
The ecu controls it mate. There is a map which plots the ignition advance depending on load and engine speed
1996 Olive Green 850 AWD - Follow the Project - Forged rods, 19T, big blue injectors, 960 TB, 3.25" MAF, Ostrich, 608 binary, arduino data display, active exhaust control with Focus RS tips, 320mm front brake conversion.
1996 Nautic Blue 850 AWD - Failed its MOT, now it's a donor for the green thing.
2004 Sapphire Black S60 D5 - The new daily hack.
You read all about it did search and came up with this pdf file
https://docs.google.com/viewer?a=v&q...PwyiADVQ&pli=1
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Did you know the EU says that you can't claim that drinking water prevents dehydration. So now you know for sure what many of have known for years that the EU is run by a bunch of nutters.
Volvostorm (Saturday 13th August 2011)
I have read that, but what I don't get, is how it manages to fire early?
i.e: on the old vacuum advance distributors, the rotor could move, and was on springs, needed more advance, the rotor arm 'moved' gets to the cylinder contact point earlier.
850 system the rotor arm is fixed, bolted to the inlet cam, to my thinking, its always going to be at the cylinder contact point at the same amount of degrees each cycle.
I know the system works, just trying to work out how!
Ah, I see where you're coming from now.
The rotor arm has a wide contact on it, so I guess it covers the programmed advance/retard angles. And the cam rotates slower than the crank so the amount of time 'on contact' the rotor arm has is multiplied.
Last edited by Dangerous Dave; Saturday 13th August 2011 at 18:44.
1996 Olive Green 850 AWD - Follow the Project - Forged rods, 19T, big blue injectors, 960 TB, 3.25" MAF, Ostrich, 608 binary, arduino data display, active exhaust control with Focus RS tips, 320mm front brake conversion.
1996 Nautic Blue 850 AWD - Failed its MOT, now it's a donor for the green thing.
2004 Sapphire Black S60 D5 - The new daily hack.
As bomb says, the spark isn't actually fired to the plug by the action of the rotor arm passing the spark plug lead contact just distributed to the relevant spark plug. The contact on the end of the rotor arm has a wide blade so that it always next to the relevant plug lead contact irrespective of the advance that the spark is fired by the ecu. The old system with contact breakers used centrifugal weights and vacuum advance system that actually moved the distributor baseplate which in turn moved the breakers around the cam lobes within the distributor effectively advancing or retarding the ignition timing, the rotor arm then distributed the spark to the relevant plug lead by it passing the contact within the dizzy cap.
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merc85 (Saturday 13th August 2011)
Thanks for all the answers, it makes sense now
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