screw gaskets

[harhas]

Recently while working on an RT engine I checked my parts manual to be sure I was using the correct screws. to my surprise I discovered that It uses a ''special'' washer 0250.70.050 under 6 screws?? This ''gasket'' measures 6,2 x 10,2 x 1 . Not sure if it is fiber or metal or it's purpose. Upon checking my WC parts manual no mention of these ''gaskets'' on springers or Desmos . I have worked on many single engines but this is the first I have encountered this question. It has been suggested by another collector that because the RT came late in Ducati's production period (1971 in US) that all the ''late'' engines used them? Another minor question is the substitution of screws that are 15mm long as opposed to 16? It would seem the 1 mm thickness would warrant a 17 mm screw?? Thanks in advance for your consideration, I have been reading scrubs for years but have never posted before. Harry

[Jon Pegler]

Those gaskets are small aluminium washers.
Their purpose is to stop oil from leaking up past the screw, as the thread in the cylinder head breaks through into the rocker shaft drilling, causing oil to leak through.
I notice that the RT parts book says there are six of these washers, although as far as I am aware, they are only required on the two upper rocker cover fixing screws. So four washers are needed on the rocker covers.
The RT parts book seems to show a similar washer fitted to one of the cam bearing fixing screws. Not sure why it would be needed there.

Jon

[LaceyDucati]

Some 450RT's came fitted with the large "Imola" style cam. These bikes had the tunnel bored larger and the cap sleeved. The upshot is the two lower screws are perilously close to the tunnel bore and thus a potential leak. This would be one potential reason, the other is that on some 450's if you use the specified length of screws on the two top holes (minus the washers) the screws foul the head studs! The seals are alloy and mostly go unnoticed as they get crushed out and stuck in the counterbores.

Nigel

[harhas]

Thanks Jon and Nigel for your responses. I also noticed the case screws in question do appear to stand a bit proud. If the screw heads appear to leak I may need to counter-bore the gasket out and fit replacements. Once again thanks for your information. Harry