What size is the N/C points cover O-ring?

[mrkprsn]

Hi Peeps,

In my parts books the points cover O-ring is referred to as a gasket. No size is given I think all the N/C engines had the same size. So before I say what I think it may be, I'd like to know what others might think.

Thanks, Mark

[bw_nh]

Good afternoon-
I just bought a new one- I will measure it later today and report.
Sincerely,
Bob Woolner
Hillsboro, New Hampshire USA

[bw_nh]

Good evening-

This is what I purchased-

https://www.ebay.com/itm/360763628671

It measures 2 28/32 inches, which converts to 2.875 inches, which converts to 73.025mm - outside diameter.

The thickness is .142 inches... which would be 3.6 mm.

Does that help?

Sincerely,

Bob W

[mrkprsn]

Thanks Bob. I measure the engine and came up with 67mm ID. In the US I ordered it from oringsandmore.com. They are $.70 and $7 for shipping. I ordered five. They are 3 mm thick. They fit perfectly. So my measurements are 67 + 3 + 3 = 73mm OD. For anyone else reading, look for an Oring with a 67mm ID and a thickness of 3-4 mm.

[Ventodue]

Based on your dimensions, I reckon that the original Italian code for this O ring is OR170.

OR170.jpg

The closest AS 568 (the standard of the SAE, Society of Automotive Engineers) reference seems to be a 231.

AS 568 2.jpg

By the way, if anyone is wondering about these curious metric measurements it's because of history. Hydraulic seals were originally measured in imperial measurements, and it's kinda difficult to change some time later on. So for example, 3.53mm is actually 1/8".

[LaceyDucati]

Craig

1/8" is 3.2mm or to be more accurate 3.175mm

[LaceyDucati]

I do stock these if in the UK.

https://laceyducati.com/ducati-parts/se ... p-760.html

Not that I like to promote business here, but I don't think it's unreasonably expensive, and I won't be making my fortune

A quick look on Simply bearing's site in the UK, who are considered cheap and there you will have to pay more and also buy two.

Nigel

[mrkprsn]

Good to know Lacey has them. I just ordered a bunch of things from them and didn't see this unfortunately. I would add that anything less than 67 ID, you will have to stretch it a little bit.

[Ventodue]

1/8" is 3.2mm or to be more accurate 3.175mm

Fair enuf, Nigel. Maybe this is the explanation for the Italian dimension being that little bit larger:

"In contrast to the AS 568 A inch system, the nominal and physical dimensions of metric O-rings match precisely. That is, a 1mm O-ring will, indeed, have a cross-section of 1mm. This means that the space that is being filled must be about 10% to 15% smaller than the cross-section of the O-ring in order for the O-ring to seal properly".

Truly obscure stuff. Love it ...

Btw, you don't need to promote your business here. We are more than happy to do it for you

[LaceyDucati]

Craig,

Who knows the origins of some imperial standards! All the O rings in the bevel single engine are Imperial, well I think they are termed Imperial.

Edina and I have spent the last few days trying to tidy and update the website and structure to try and accommodate new items. Hopefully it will be easier to negotiate and find things. No small task and I have to say, lack of time and proper attention recently had let a few things get out of shape. Apologies to anyone who's been on the site over the last few days, as things would have been moving about a bit Should be done with the major changes tomorrow, but still lots more items to add.

Thanks for any kind words, always appreciated

Regards Nigel