Author Topic: Manual advance questions  (Read 705 times)

Offline Drew Back

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Manual advance questions
« on: 12.09. 2017 13:31 »
I have to reset timing on my 1958 rocket it has the manual advance/retard. I just want to make sure that with lever at rest(no pull on cable)is the advance position, and when I move lever forward pulling on cable is the retard position..When cable is pulled cam ring goes in clockwise direction same as the mag.. I have read all the posts on this I just want to make completely sure this is 100% correct so I don't have to do it again and again. Thank you in advance for the input...

Online Billybream

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Re: Manual advance questions
« Reply #1 on: 12.09. 2017 15:58 »
That's correct, best to ensure you have a little slack in the cable
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Online Triton Thrasher

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Re: Manual advance questions
« Reply #2 on: 12.09. 2017 17:56 »
Yes, advancing is the cam rotating in the opposite direction to the points' rotation.

Offline duTch

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Re: Manual advance questions
« Reply #3 on: 12.09. 2017 21:00 »

 Probably sting the obvious to some, but one way to remember which way, is the points lobe travels further to reach the cam lobe as does the piston when retarded. Conversely the points lobe meets the advanced cam lobe earlier. That may be of help  *dunno*
Started building in about 1977/8 a on average '52 A10 -built from bits 'n pieces never resto intended -maybe 'personalised'
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Offline Drew Back

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Re: Manual advance questions
« Reply #4 on: 13.09. 2017 02:43 »
Thank you for the imfo got it set tonight, fired first kick purs like a nice kitty. Will take for a test ride this weekend.

Online Rex

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Re: Manual advance questions
« Reply #5 on: 13.09. 2017 21:21 »
I don't know enough about 1958 SR's to argue the toss, but 1958 sounds much too late for having a slack-wire advance mag? I understood the convention changed to slack-wire retard in the 1940s, but I'm no expert... *conf*

beezermacc

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Re: Manual advance questions
« Reply #6 on: 13.09. 2017 22:29 »
All the BSA twin cylinder sports models had slack wire advance from the late 1940's. Nearly all K2F's are anticlockwise drive and have a cable housing on the left of the cam housing so, when the cable is pulled 'tight', the cam rotates clockwise which delays the moment when the points open i.e. tight wire retard.... slack wire advance.

Online groily

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Re: Manual advance questions
« Reply #7 on: 13.09. 2017 22:42 »
Not on twins Rex. Many singles ran with tight advance but K2Fs on most marques - and I think all Beesa twins not fitted with atds - are slack. Default position thereby being 'full advance' in case of lever slippage at the 'bars.
Lucas made contact breaker housings for cable entry on either side for most mags (to cater for opposite rotation on some marques as much as anything) so all sorts of things are to be found out there, certainly.
The Lucas parts lists of the day show just how many versions there were of all the common mags and magdynos and which machines they were fitted to originally - they do not make easy reading though!
And I see Beezermacc beat me to it   . .  luckily we're saying the same  . .  !
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Online Black Sheep

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Re: Manual advance questions
« Reply #8 on: 14.09. 2017 06:31 »
Lucas magdynos are a case in point. The magdyno on my B31 was tight wire advance. It was a simple exercise to convert it to slack wire advance which brought it into line with my twins. I suppose timing failing to fully retarded didn't matter too much on early machines but was a bad thing on later ones. Big loss of power and red hot exhausts.
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