Tuesday 4 November 2014

Norton CS1 Moore Engine Bevel Setup

-SG- David in New Zealand has sent us the below which may help those pondering on the best way to set up a Moore CS1, bearing in mind the not very explicit information in the instruction books of the time.

  1. Fit the crank bevel to the crankshaft using a fresh woodruff key.
  2. Fit the oil pump worm drive.
  3. There is a notch on the crankshaft. Line this up vertically with the dot on the lower bevel and the dot on the lower bevel bearing housing. The piston will be at TDC.
  4. Insert the bevel shaft with the upper bevel dot to the rear in line with the cam shaft.
  5. The cam bevel has 3 keyways. One is directly opposite a tooth, one to the left of a tooth and one to the right.
  6. Choose the keyway on the cam bevel that provides for the cam lobes to be at the bottom of the shaft i.e. inlet and exhaust rockers closed.
  7. Align the dot on the upper bevel with the dot on the cam bevel.
  8. The above set up will time as TDC.
  9. Set up and measure the valve openings / closings as per below to confirm timing.
  10. NB – if the timings are out you may have to move the cam bevel to a different keyway, thereby advancing or retarding the valve timing. This system of 3 keyways is the precursor to the vernier timing seen in Carroll OHC models from 1930 on.
  11. Once you have timed your engine you need to check the bevel mesh and backlash.
  12. Each pair of bevels should mesh together perfectly i.e. the outer edges of the bevels should align.
  13. The bevels should have between 1 to 2 thou backlash – just a perceptible click – not a clunk!
  14. Adjust by shimming both bevel gears to retain the perfect mesh.
  15. Start at the crank and work upwards ... a long and tedious process but essential to trouble free and relatively quiet running.

The numbers:

Crank bevel: 24 t, Lower bevel: 36 t, Lower ratio: 0.66:1  
Upper bevel: 27 t, Cam bevel: 36 t, Upper ratio: 1.33:1
Overall ratio: 2:1

Valve Timing Specifications of a 1929 Norton CS1:
Cam details: E2531 Race Cam, re-mastered                    
Tappets - Inlet: 0.006", Exhaust: 0.010"                                      

The following are measured at the top of the valve stem at the above tappet clearances

Opens BTDC 32°                                            
Closes ABDC 56°                                            
Duration 268°                                          
Lobe Centre* 102°                                          
Lift 0.376"                                      

Opens BBDC 62°                                            
Closes ATDC 30°                                            
Duration 272°                                          
Lobe Centre* 106°                                          
Lift 0.37"
* Lobe Centre target is between 100° and 105°