Advancing or retarding?

[Parazine]

Are we talking at cross purposes??

Nick has quoted  a magneto engine handbook. I think that a mag gives a stronger spark when it is advanced up, to do with internal timing, i.e. points opening vs. maximum flux. So the distributor stuff doesn't apply in this case......

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And maybe Austin technical authors didn't change this when coil ignition was introduced......

[Chris KC]

I may be out of my depth here but I thought mag sparks got stronger with increasing speed rather than with advance - although of course the general aim is to increase advance as speed increases. In the near-static conditions of a handle-start a strong spark is a boon but it needs to occur fairly late compared with the 'at speed' condition. This surely applies irrespective of ignition source?

Edit: Though I think that coil engines are sometimes advanced further than mag engines to compensate for the weaker spark at speed; as fundamentally ignition timing is determined by a combination of flame rate and engine speed, and the stronger spark from a mag promotes a higher flame rate.

[Howard Wright]

Hi All

I have been looking at Handbook 715A for Coil cars.  It still suggests that the ignition control remains largely advanced and only retards when the engine rumbles.

Cheers

Howard

[Zetomagneto]

A mag gives a stronger spark at low/ cranking speed when fully advanced, not ideal for hand starting,l
do not start my car on the handle, it's got a starter to start it

[David Stepney]

The ignition timing on my RP is set to 1 9/16ins Btdc fully advanced. I leave the lever fully advanced as the car seems to run better that way. I too use the starter to start it hot of cold. And it always starts promptly.

[Parazine]

I agree with Zetomagneto. As I said, it's to do with the fact that the points should open at magnetic flux peak on the primary side and this is internally timed to be when max advance is set up.

According to Nicholson (P171, 2nd ed, The Gregg Publishing Co. Ltd. London 1928) 
"The reason why coil ignition is more sensitive to advance and retard adjustments lies in the fact that the magneto spark is automatically advanced with increase of its armature speed, whereas the coil spark is - so to speak - stationary as regards the movement of its occurrence in relation to piston movement. For the reasons given, it is essential that the ignition lever should be well retarded in starting on the coil - particularly when the engine is stiff - as it is when new or in cold weather: otherwise you are quite likely to get a backfire, which will work either against you or the starter, at the risk of injury to one or the other."  

I also don't start my mag engine car on the handle because:

a) It's hard work.
b) It has a perfectly good starter motor.
c) The starting handle shaft dog end is worn and is likely to slip on the engine dog.

[Steve kay]

Puzzling that a handbook from Longbridge should contain such an inaccurate piece of advice. A final effort before retiring was to take a few period handbooks and manuals down from the shelves, and referring to manual coil ignitions, retarding for starting is recommended by all. In the days of predatory lawyers, the PR department would have been told to quickly update the handbook before a flurry of cases dealing with injuries to wrists. Whilst I never want to sound bossy, on odd occasions I have felt moved to quietly suggest to some hand starters what many of us forumists were taught to do with our thumbs, NOT round the starting handle. A kicking back Seven may cause bruising but I will not be the only person to know what a National or JP Lister can do when in a bad mood for starting.

[Nick Salmon]

I started this thread firstly to confirm I had not spent a lifetime using incorrect terminology but mainly to see what the collective view is about Austin giving the instruction to nearly fully advance the ignition for starting. 

I just looked up (on A7CA archives) the 1922 handbook. The early cars had no starter so it was all hand cranking - and lo and behold - the instruction is to retard the ignition.

Why would they instruct that on the early cars but then change it to advance when electric starters first came in but where they were advising to use the starting handle when the engine was cold etc...


Perhaps there is no definitive answer to this but thanks for the replies so far. I shall happily continue to retard the ignition when using a starting handle!


  start.JPG (Size: 34 KB / Downloads: 150)

[Chris KC]

I'll bow to the wisdom of others as I've never owned a mag ignition car. I would say though it has always given me great satisfaction to be able to start my car with a single flick of the handle - when cold at least. Sadly since rebuilding the engine she's not quite on song again just yet, we didn't get out much over the summer.

[Parazine]

Whilst I never want to sound bossy, on odd occasions I have felt moved to quietly suggest to some hand starters what many of us forumists were taught to do with our thumbs, NOT round the starting handle.

When I first had my Ruby in the seventies, I used to start it regularly on the handle as my battery was in a constant state of exhaustion. It frequently "kicked back" and I didn't know about not wrapping my thumb around the handle. After a few months, I had an incredibly painful hand, at the base of my thumb. I consulted my GP, who examined my hand and puzzled, looked at me, saying: "I haven't seen this injury for years. It used to be common in the days when people started their car with a starting handle!"