My W/NG is now almost finished apart from a few cosmetics to complete........I've owned this bike for over 20 years and rebuilt her twice over this period........most recent attention was to sort-out a dead magneto, full service and a general tidy-up as she's been off the road since early 2012...........

Anyhow, liquids in and she started first kick yesterday and ran beautifully......settled down after only a few moments to a nice steady tick-over.......and did the same today.........

I set the ignition timing with the head off, both valves closed, piston at TDC and handlebar control fully advanced.........points about to open with the piston 3/8ths BTDC.............

The wonderful Pitman's series of books include "The Book of the Ariel" written by W C Haycraft...........I have several post-war editions.........all state that the OHV's, including the NG and older models, should have the timing set at 3/8ths BTDC with the exception of the sportier Red Hunter's which should be set at 5/16ths BTDC.............

Yet a check of the W/NG workshop manual and instruction book states that the W/NG should have the piston set 1/2" before TDC...........mine runs like a top though on 3/8ths !

Ignition timing is clearly important though, and I'm wondering if the wartime setting of 1/2" had anything to do with fuel or another rationale ?

Steve in the case of poor quality fuel, it would probably be more prudent to retard the ignition rather than advance it. Most other WD OHV 350's are set at 3/8" with G3L being 7/16". So 1/2" is even more advanced than most. I think I would go with the makers recommendation or at least take advice from an Ariel expert. Maybe a phone call to Drags and let us know what they say. Ron

email (option): ronpier@talk21.com

Thanks Ron........puzzling though, as both the Ariel workshop manual and the Haycraft book were written in consultation with the factory............and mine runs VERY well on 3/8ths ! Not something worrying me, but I'm curious as to why they changed the ignition timing recommendations post-war for iron head/barrel OHV's of essentially the same specification...........

Soon be back on the road.......Mrs M can't wait !

Probably a miss print. Half an inch seems really excessive. I've found a couple of different figures for the ignition timing for a 16H in the manuals I have. I think if you ran with 1/2 inch fully advanced it would "pink".

You may have a point there Keith ! The 1940-dated Ariel W/NG rider's instruction manual states the ignition timing as 3/8ths before TDC which is also what "Haycraft" states.........

Interesting to note within the wartime DME circulars, mention is made of the ignition timing for Matchless machines........and this requiring "immediate action" too.....

Circular No. B116 of 29/4/41 mentions the fitting of a compression plate to Matchless engines.......

Then Circular No. B116/1 of 27/3/42 mentions an amendment to the above circular. It states "delete 5/8ths before TDC and insert 3/8ths before TDC"..........this only affecting Matchless models however according to the instruction........

There is additional mention of ignition timing applicable to all motorcycles in DME Circular No. B174 of 8/8/41 but no detail is given.........

Hi Steve,
It all depends on which cam you have fitted.
If yor cam is marked A6/599 or F as fitted to the VG,NG, LG, OG the timing should be set at 3/8"BTDC fully advanced. If you have the 1939 "hunter cam" marked A7/642 these models should be set to 1/2"BTDC fully advanced (as mentioned in the W/NG service manual). The "red hunter" models fitted with this cam (VH,NH,LH,OH)should be set to 1/2"BTDC for touring or 5/8"BTDC for high speed work(whatever that was)!
Cheers, Mick.

email (option): mick@motorbikemike.org.uk

Well done Mick for this reply. It seems we need to check our cams before timing the ignition. I will be printing you specifications as an addition to my workshop manual.

Ron

email (option): ronpier@talk21.com

Hi Mick ! Thanks for this...........

Seems odd that the "Red Hunter" timing was specified in the W/NG workshop and instruction manual........within my many parts lists, including early, I can't find any reference to the "Hunter" cam being fitted.............maybe, just maybe, it was an error ? My copy of the workshop book makes no reference to an alternative cam being fitted but it is a late edition (3C)..........maybe an earlier edition refers to this ?

Hi Ron
i am not sure why ignition timing would be retarded with poor quality fuel? I would have thought it would be slower burning hence more advance would be needed.

email (option): pvlietstra@gmail.com

It would be retarded slightly to reduce the tendency to pre ignition inherent in lower octane fuels...

Whilst that result would be achieved it would be gained at the cost of a slight loss in performance as well..

The same strategy was used initially following the introduction of 'lead free' fuel where the (removed) lead was the 'anti knock' agent in the fuel....Ian

email (option): ian@wright52.plus.com

I set mine at 1/2" and found out that if I retard it a gnats on the lever it goes better, it didn't pink though on full advance just felt a bit strangled!

email (option): barryrapley@sky.com

I've plumbed for the 3/8ths setting and it goes a treat....no holding back !!!