Pre-38 single valve gear

[chris.kelly]

Wot ho chaps,

Is there a trick to reassembling the valve gear on pre-38 singles with the rocker return springs in place?

The only way I can see to do it is to assemble the valve gear onto the spindles, attach the mounting plates to the spindle ends, and then screw the two rocker box halves together.

The problem with this approach is that it forces the upper rocker box half to press the fixed end of the return spring to place (into its little slot in the lower half), when what it wants to do is is to rotate in the same direction as the end attached to the rocker arm.

The obvious solution would be to assemble it without inserting the spring end into the rocker arm, but there's no way to insert it afterwards (the spring end is too long).

On a related note, why did they use the return springs in the first place? Were the cams so 'hot' that the followers needed the extra spring pressure to make sure the followed the cam contour?

[nevhunter]

The reason for the return springs is to keep the pushrod ends in contact with the rocker /cam follower ends. If they jump out partially, due to a momentary sticking valve, the valve could be opened too far, and bend and break things. Nev