This is the base barrel gasket of the shape originally fitted to all single cylinder 500cc models through the 1930's - Norton Part No 9139. It also continued for Side Valve engines post-war (as Part No C2/157), but can also be used on other 500cc post war models. Manufactured from high grade and slightly pliable oil jointing material.
If you look at most Norton Spare Parts Catalogs through the 1930's, you will see the 500cc/600cc Cylinder Base Washer (Barrel Base) gasket was of this design - and was fitted to all 500cc models, i.e. - SOHC: Model 30, CS1. OHV: ES2, Mod 18, Mod 19 (600cc), Mod 20 (twin port). SV: 16H, Model 1 (600cc) Side valve models up to 1938. (Note: for Side valve non-WD models from 1938 - 47 this gasket was replaced with a full gasket - our part no 0927, while the earlier design WD military 16H engines continued to use this gasket)
The same shaped cylinder base washer continued to be listed on postwar Side Valve models (as part number C2/157), but the base washer for OHV and SOHC models postwar changed to an 'open' type where the profile of the washer around the cylinder studs followed the profile of the barrel and was less square than this type.
The version we list here is made from a good quality oil jointing material - and with a variety of oil drain holes around the circumference, making them also suitable for many single cylinder models. However, if using on any barrel with drain holes - it is important to ensure that the barrel/crankcase mouth drain holes line up with at least one on the gasket - and if not, open up the gasket to ensure they do ... as there were numerous variations on the different models over the years.
These are manufactured from high grade and slightly pliable oil jointing material - which are of a type I have found particularly effective on barrel joints in the past, as they have a little more 'give' in them than the more traditional brown paper washers - which can be useful if your crankcase barrel mouth is not in best of conditions, or has a slight lip between crankcase half's.
We also offer paper base gaskets, of the type fitted to OHV models postwar - but I particularly like this base gasket because of the quality of the jointing material - therefore it is also worth considering one of these if you have a postwar OHV or SOHC machine - and you can easily trim away the excess gasket material around the cylinder studs if you want to make it look like the later OHV and SOHC postwar gasket.
This gasket is manufactured for us in good quality oil resistent gasket material by a well established UK gasket manufacturer