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A10 caqm timming spec's

Posted By: flattop

A10 caqm timming spec's - 12/07/17 7:54 pm

Hi All
I have unfortunately miss timed my camshafts. The dot s and lines do not seem to fall in place where it will start and run.
Beings I did this twenty years back , I've bought it back from my brother in law.
Time to get back at it.
I need a specification or procedure for resetting them.
Of course he fiddled with the mag , I think i can retime that .
thanks Tony
Posted By: Red Lapierre

Re: A10 caqm timming spec's - 12/08/17 2:29 pm

Flattop
PM me or post an e-mail I will send you a copy of the instructions from BSA manual.
Red
Posted By: flattop

Re: A10 caqm timming spec's - 12/10/17 4:22 am

Thanks Red
pm sent
Posted By: Red Lapierre

Re: A10 caqm timming spec's - 12/10/17 1:47 pm

e-mail sent.
Posted By: Red Lapierre

Re: A10 caqm timming spec's - 12/11/17 7:41 pm

Sent more pics and instruction.
Posted By: flattop

Re: A10 caqm timming spec's - 12/12/17 4:04 am

Thanks to Red I just realized I been thinking Triumph twin cam.
So only one cam to time in.
I do not think it has stock cam and the fellow who built it up originally has passed.
Would there be a intake opening or center line number to hit.
Such as 18* before tdc @ .050.
I need to recheck it all , surley must be off a tooth.....or more possibly the key .
Thanks again

Posted By: Red Lapierre

Re: A10 caqm timming spec's - 12/14/17 2:00 pm

BSA service sheet #216 A group (swinging arm frame)

Valve Timing-inlet (deg) A10
opens before TDC 30 deg
Closes after BDC 70 deg

A10 RR or SR
opens before TDC 42 deg
Closes after BDC 62 deg



Valve Timing-exhaust (deg) A10
opens before BDC 65 deg
Closes after TDC 25 deg


A10 RR or SR
opens before BDC 67 deg
Closes after TDC 37 deg





Note: after engine numbers CA7_5232 and DA10_1647 the valve timing for A7 and A10 is the same as the SS and Rocket machines. Tappet clearances for quiet running should be .008 in. inlet .010 in. exhaust, but for maximum power .010 in. inlet and .016 in. exhaust

Hope this helps
Red

Posted By: Allan Gill

Re: A10 caqm timming spec's - 12/15/17 2:13 pm

Red, i'll have to check those timing figures but they look more like the ones used on the plunger models (or circa 55/56 A10) the notation about .010 inlet and 0.016 is also not correct, those were standard valve lash figures for the early cam, the "maximum power" figures were rated at 0.010in and 0.012ex

In the UK though both Flash models and SR models were fitted with the late touring cam, (same specs as on the A65) the RGS and the export SR were given the spitfire/sports cam.

spitfire/sports cam:

Inlet:
Opens 51 BTDC
Closes 68 ABDC

Exhaust:
Opens 78 BBDC
Closes 37 ATDC

Touring cam:

Inlet:
Opens 40 BTDC
Closes 60 ABDC

Exhaust:
Opens 65 BBDC
Closes 35 ATDC

Of course a lot of this depends on what year the bike is?
Posted By: Red Lapierre

Re: A10 caqm timming spec's - 12/15/17 3:59 pm

Allan you might be correct? But on the page it has A Group(swinging arm frame) Useful Data
The info I posted was from a BSA service manual I have that page was revised in 1963 and reprinted in 1965 the note on valves was on bottom of that page No. 216
I don't know if there is a different from UK to US models the book don't say which one it would be for.
Red
Posted By: Allan Gill

Re: A10 caqm timming spec's - 12/15/17 10:22 pm

Interesting, I have kims CD somewhere so I will double confirm. It was help if the poster gave us a bike year.
Posted By: Andy Higham

Re: A10 caqm timming spec's - 12/15/17 10:38 pm

Don't rely on the timing marks that BSA stamped on the gears.
The A10 I used to have first with a 356 cam then later with a 357 I ended up making stepped a stepped key to get the cam timing to spec.
If I was doing it again I would machine the centre out of the cam gear and make a new hub. The hub would have a ring of holes that corresponded to a ring of holes in the gear but one less, depending on which holes were aligned with a peg would give a fine (vernier) adjustment of the timing.

The biggest fukc up in the A10 cam arrangement is the followers, the hardening is too soft and too thin. I had a set stellite welded and ground, many thousands of (hard thrashed) miles later the cam and followers were still as new
Posted By: chaterlea25

Re: A10 caqm timming spec's - 12/15/17 10:45 pm

Hi All,
If parts (cam wheel or idler ?) are mixed from the plunger engine to S/A the timing marks will not "work"
Search for threads on this on the A10 forum

John
Posted By: Andy Higham

Re: A10 caqm timming spec's - 12/15/17 11:45 pm

If you are happy with near enough or it's only 5 degrees out use the marks. If you want it right be prepared to put the work in. you will need a DTI, degree disc, keys and files. BUT who says BSA's figures are right? advancing the cam slightly will make a bit more power at low RPM at the expense of top end power, retarding the cam will have the opposite effect
Posted By: Dave - NV

Re: A10 caqm timming spec's - 12/16/17 12:03 am

As Andy has mentioned - Do it Right! Be sure to use a 'bump stop' to determine an accurate TDC. Lucky for us Gold Star Guys, vernier cams are available from Phil Pearson in England that allows you to set an accurate cam timing in 1 degree increments. I've played around retarding and advancing cam timing with no improved results over BSAs factory timing of 42 and 46 cams accurately set to factory specs. Always bear in mind the importance of the accuracy of the placement crank gear keyway.
Posted By: flattop

Re: A10 caqm timming spec's - 12/18/17 12:29 am

Thanks Everyone I feel I have the info I need.
It is a 1960 A10.
I have all the needed equipment.
At this point if I get it close enough to run I will be overjoyed .
as I stated it was perfect before I muddled it up.
would start with hand on the kick lever.
Seriously 25 years back minimum.
Posted By: Allan Gill

Re: A10 caqm timming spec's - 12/18/17 10:42 am

Not sure what the tooth count is on the A10’s but on the A65 each tooth is equal to 16.5 degrees of crank movement, I believe the crank pinion is 22t same as the A65 (so I would think the other gears will be 44t) if you failed at least one lobe and found that it was more than16.5 degrees, you could move the crank pinion one tooth either way (which ever way gets you closer) and the engine will run fine if it is 5 degrees out.

Hope that makes sense
Posted By: flattop

Re: A10 caqm timming spec's - 12/18/17 9:25 pm

Allen
That does make sense.
Funny I was just thinking I needed to count the teeth the do the division.
Best to do the degree wheel at this point.
I also have a spreadsheet that give degrees rotation to piston movement.
would need the head off though to be accurate..
just gauging it visually it looks off a considerable amount as the valves appear to be opening and closing at entirely the wrong times.
another funny thing I opened the manual to check stroke and the spec were right there.
Thanks for all the help.
Posted By: Allan Gill

Re: A10 caqm timming spec's - 12/18/17 11:56 pm

No worries, good luck and ask all you need to.
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