Hi all. I've just had the magneto rebuilt on my recently acquired 52 Rapide and would appreciate some advice on how I go about setting the timing and what settings to use. I'm a little confused as to whether the setting of 38 degrees btdc is correct and whether that is set at full advance. Thanks in advance for any replies.
Timing a Rapide
- Thread starter Peter Ball
- Start date
ATD (auto timing device) I'm assuming you are using although not a favorite of mine, although fitted a new one last year for a new member and considered it a much more robust affair, Timing disc into quill hole TDC found by old plug with extended vented steel rod welded in-place of of the porcelain as positive stop method. Fine grinding paste to check fit on taper and thread on armature runs freely when screwing on nut. Wire the ATD into fully advanced position, turning the engine forward (taking up slack in gears) setting the rear cylinder (No 1) to 32 to 36 degrees, points about to break, tap ATD onto taper and tighten up nut watching armature does not turn separately to timing gears, Compression Ratio has an effect on degrees 9 : 1 CR // 32,,,,,,,,6.7 : 1 CR // 36 degrees, twin plugs 23 to 26 degrees.
The mag armature can be helped stopping from turning by removing the earth brush and screwing a bolt in it's place WITH YOUR FINGERS to just nip the shaft,
DO NOT USE A SPANNER, and don't forget to take it out and put the brush back.
It is usually 5/16 BSF but check first.
A tap may be needed to clean carbon/muck out of the threads.
DO NOT USE A SPANNER, and don't forget to take it out and put the brush back.
It is usually 5/16 BSF but check first.
A tap may be needed to clean carbon/muck out of the threads.
When I remember all that taper grinding and slippage I am so glad I have a BT-H that locking bar idea could only have come from someone who had suffered the Hassel of timing the normal mag. Well done Tony just shows how far Lucas designers were from users experiences.
Or even a distributor
. So much easier to watch the ammeter to see when the points open and close and to have final fine adjustment just by rotating the body of the distributor.
. So much easier to watch the ammeter to see when the points open and close and to have final fine adjustment just by rotating the body of the distributor.
The grinding paste work should be done with the mag off the bike, just in case there was a misconception. The taper can be locked by having the nut screwed in just short of nipping and then the ATD tapped with a socket fitting over the head of the nut. Then the nut can be tightened without the torque shifting the setting. This has some good ideas http://www.vincentownersclub.co.uk/index.php?threads/ignition-timing-modern-fuel.6399/page-3 I bought the $15 LCR meter and it works well.
I keep meaning to see if I can convert a "normal" mag to be able to use locking bar like my BT-H
You may be able to, as I say making maintenance things easy would never have occured to Lucas designers and yes Bruce I know the proceedure but once in every few times when you check the setting....
Thanks for all the replies. However.......! I'm still none the wiser on actual settings. The books I have seem to suggest that a figure of 39 degrees btdc at full advance is correct for a 1952 Rapide with standard 6.3(?)compression ratio. Yet Marcuus reckons it is anything between 32-36 degrees btdc fully advanced. Can I get some clarity on this figure?