A10 Timing

[Richard]

Can any one inform me of the degree's I would be looking at if I wanted to know what 5/16ths BTDC was?
I thought I had it written down somewhere but can not locate it and yes I am sure there must be a simple formula for working it out but at present my brain is on a go slow due to the tablets I popped
many thanks
Richard

[trevinoz]

Richard, it is about 32 degrees.
I will e-mail you a converter chart that I got off one of the forums.
Trev.

[Richard]

Trev
Many thanks I have just retrieved the converter chart this morning.
I thought it was about 31 or 32 degrees
I have a fellow club member coming over this morning for me to help set his A10 timing but I started to have some doubts as to the exact degrees as SRM had told him 35 degrees and now under load his bike is pinking.
I always set my S/R to 5/16ths even though it says 3/8ths to make allowance for our present fuel and it works for my bike.
once againthanks
Richard

[trevinoz]

Richard, in Eddie Dow's tuning notes, he recommends 5/16" before TDC.
Forty years ago they pinged with 8.75:1 compression even with the real fuel we had then.
The problem, I feel, was the ridiculous 13/32 advance figure given in the service sheets. 
Trev.

[pete j]

I had pinging at 13/32 BTDC, set to 11/32, still pings but less, should try 10/32 or 5/16 next. 1960 A10 GF

Pete

[G/F DAVE]

I run my 1952 A10 plunger that has 7.25-1 comp at 34 degrees btd with no pinging or problems I,m also using a 376 camshaft makes for a nice motor.  G/F DAVE

[Richard]

Trev
Job done however I could not use the conversion tool you sent as when I tried to change the details in the second bos for the stroke it requested a password.
I decided to set it to 32 degrees with the view that backlash in the gears and eyes that are a bit on the tired side along with a bit of tolerence in the auto advance gear and the fact I set the points to 15thou to allow for the fag paper it would be about right once I had reset the points to 12thou when done,I had to redo it three times as each time I rechecked it was out either the disc was out checking for TDC or the points had moved slightly when tightening up once it checked out three times after turning the engine back and bringing it back up to 5/16BTDC I called it a day.
It started first kick and ran a treat I saw John the next night at the branch club meet and it was going and sounding bootiful!!
So thanks for all the help and comments lads another success
Richard

[trevinoz]

Richard,
            It's strange that the programme wants a password. I just tried it and it worked fine.
I am pretty sure that the figures in the table are for the A10, anyhow.
Trev.

It will be interesting to hear how your bike performs on a decent run.
By the way, what compression and camshaft are you using?

[Richard]

Trev
it was a fellow members bike I have just timed, my S/R goes well I have 80thou 8:1 pistons or they may be 8.25:1 I really do not know as for the camshaft I never looked at the number but I would imagine it is a spitfire cam  however whatever it is it is fine as it motors along nicely and sounds ok
I am just off to earn a shilling now so will try that conversion again later
Richard

[a101960]

It was my bike that Richard re-timed, and it has made a big difference. The pinking has now gone, and the plugs are now a much darker coffee colour, so well done Richard. I would also like to mention another ignition related problem that I had experienced a while back. Different burn rates between the cylinders. One was always leaner that the other. Both cylinders now burn identically. The reason that this was happening turned out to be that not only was the cam ring worn, but also the the bearing in the points housing had worn off centre. I had initially fitted an anti-bias spacer that did effect a partial cure, but it was not the answer. What the anti-bias spacer did was to mask the symptom without effecting a lasting cure. If any of you are experiencing uneven burning between the cylinders check out the magneto that's where your problem will be. As a matter of interest my mag had been rebuilt and electrically it was perfect, but do not take it for granted the the mechanical tolerances are satisfactory. That had me stumped for quite a while. Mind you I am not mechanically minded, and that does not help either!

[trevinoz]

When I build an engine I time it with the head off and check both sides firing position. Normally they are nowhere near each other so I "adjust" the points cam until they are both close enough.
Trev.