478 v. 501 top end differences

[simonnorthroad]

I found an old posting from Norbert from 3 years ago, thusly:


the pushrods of the 500 motor are longer than the ones for the 501 because the 478-cilinders are higher! Another diference is the axe of the balancines (spanish ) They are 71mm long instead of 69 (350 and 500) if I remember it well, and the distance washers are put in another order. The reason is that the center of the valves in the 501 heads are more apart to avoid the problem of the fissure between them (still happening ) That means that the puschrods are positioned a bit out of vertical.

I once took the longitudes of the diferent pushrods in mm (over all) the rear ones are more or less 2 mm longer than the front ones, as you know:


500 and 250T: 205/207 (I supose the 250T 205)
501: 202/204
350: 182/184

Can this be true? Shorter pushrods and longer rocker-arms in the 501 motors? Sounds pretty extrvagant by Morini standardisation standards!

[simonnorthroad]

Anyone?!

[norbert]

The rockers are the same, but the axle of the rockers in a 501 head are 71mm long. In all others 350 and 500 the axles are 69 mm long.

norbert

[simonnorthroad]

what about the pushrods Norbert?

[norbert]

The length of the pushrods is like written above. The 501 rods are shorter than the 500, because the cilinders are shorter (with 71 bore instead of 69). The crankshaft is the same, but the position of the "eye" of the piston is different, so it works with the shorter cilinder.

[simonnorthroad]

I knew you'd know! No wonder my 500 pushrods dont work in the engine!