MochetVelo Posted May 23, 2010 Share Posted May 23, 2010 Could anyone describe the steps to time a magneto on a pre-war car? My car has no spark adjustment once the magneto is set.Phil Link to comment Share on other sites More sharing options...
Restorer32 Posted May 23, 2010 Share Posted May 23, 2010 Does the mag have an impulse unit and are there marks on the flywheel? Link to comment Share on other sites More sharing options...
MochetVelo Posted May 23, 2010 Author Share Posted May 23, 2010 (edited) I translated the Frech manual and find there is a mark on the flywheel: "ALL". This must mean something like "TDC" in French(?). Anyway, it says to align this with a mark on the magneto gear and the descent of the exhaust valve of cylinder #4. I can't see any mark on my magneto. Anyway, I assume the spark is required just past TDC. The setting may be tricky as the magneto has no spark advance.Thanks,Phil Edited May 25, 2010 by MochetVelo (see edit history) Link to comment Share on other sites More sharing options...
1913Moline Posted May 27, 2010 Share Posted May 27, 2010 This looks like a Bosch ZR or ZU magneto. If you flip open the oil cover on the top, you should be able to see the marked gear as it passes. I can send you timing instructions if you provide the exact model of your magneto. Link to comment Share on other sites More sharing options...
MochetVelo Posted May 27, 2010 Author Share Posted May 27, 2010 It's a Bosch ZA4. Phil Link to comment Share on other sites More sharing options...
MochetVelo Posted June 5, 2010 Author Share Posted June 5, 2010 We succeeded in setting the magneto timing and starting the engine today. Here is what we did to time the magneto:Turn crankshaft until piston #1 (the one in front) is at TDC (Top Dead Center: as high as it goes).Mark flywheel to indicate this position.Open front of magneto to view rotor. It should be positioned over the contact connected to the #1 spark plug. Sometimes, the magneto gear has a line on it to indicate this position. Our Bosch also had the letter "D".Tighten connection of magneto shaft to engine shaft.We then tried starting the engine with the crank. It wanted to kick back, so we retarded the spark slightly. This is done by turning the magneto shaft slightly anti-clockwise (opposite its normal direction of rotation). If the spark occurs too early, it can throw the crankshaft backwards and injure your arm. A couple more cranks and it started!This magneto has no retard/advance lever, so the timing must be set as efficiently as possible, but mainly to avoid kick-back on the starting crank.If this in in error, feel free to correct me, but I though I'd post our results in case someone refers to this thread in the future.Phil Link to comment Share on other sites More sharing options...
Guest cben09 Posted June 6, 2010 Share Posted June 6, 2010 You got it running,,,3 cheers,,,If you crank too slowly,,it MIGHT kick,,but too slowly and the mag wont spark,,,If you open the plug gap it can turn faster before sparking,,a tradeoff,,some motorcycles are set up this way also,,It can work but its a tradeoff,,,,for me I would look for a mag w/a turning breaker box,and hide the retard wire/handle,,,Good luck Ben Link to comment Share on other sites More sharing options...
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