bsa pre unit single cams

[mark2]

I need the technical spec (lift duration) for bsa cams , can anyone help me with this info thanks

[iansoady]

Tuning for Speed by Phil Irving has a table which I'm sure includes the Goldie etc. When I have a moment I'll see if I have a pdf.

[mark2]

thanks , in case this helps, the cams on the left are the ones I need to id, they are narrower but I think I could use. I am trying to de tune my BSA

[iansoady]

Attached is pdf of the BSA page from Tuning for Speed.

[chaterlea25]

Hi Mark2,
Are there numbers or letters on the cams? from those their application can be identified
If you go to fit performance cams (goldie) to iron engined B31/33's you need to check that the underside of the valve cap/collets does not foul the top of the guides also that the followers do not foul the shoulder on the pivot pin or crankcase
There are other combinations that work as well there was also a 10 degree advance pinion available, recommended for the 350 engine

HTH
John

[mark2]

thanks ,going by the lift looks like the left hand pair are both 2450s , not sure as they will work as a pair but only one way to find out

[chaterlea25]

Hi,

going by the lift looks like the left hand pair are both 2450

So two exhaust cams

I dont know how the cams could be id'd by the lift ?

It may be possible to run with the  2450 as an inlet cam if you have to, but I would set the timing with a degree disc for best results
40 teeth on the cam pinion so one tooth = 9 degrees
A stepped mainshaft pinion key can be made to make finer adjustments
Check the cam duration, and calculate lobe centre of the original and new cams
Set the new cam with the same lobe centre position to start off with and then check the overall timing

HTH
John

[mark2]

2450 cam has a lift from the inch base of .385 which the left two have , the right hand have a lift of .400 from the .900 base and I think are 2446  , I have not set up for duration as I may fit and disc the deg in situ , I am looking to give the motor and my right knee a easy life so de tuning , the loss in performance is expected

[chaterlea25]

Hi Mark2
Ah you only told half the story???
Fit  two 2446 as used in the scramblers, it gives a much more tractable engine than the roadrace setup
This is what I have selected  for my engine build, as I like lots of midrange power,
I'm getting too old for head down and arse up 

John

[mark2]

I have 2446 cams fitted now and it goes well , I would like it to start with less effort if its possible

[mark2]

anyone id this one ? it has a bsa mark

[chaterlea25]

Hi Mark2
What carb is fitted?
If theres a high comp piston fitted then the magneto needs to be at its absolute best
It may be possible to add a compression plate ? or lower comp piston to aid easier starting

John

[mark2]

carb is concentric , truth is ive got to old after owning the bike for 38 years , I will cc and look at the comp this maybe the way to go .