Wrong timing cover?

Any chance of a photo to help with identification. There are at least 6 different versions of timing cover for the pre- Commando big twins.

I am fairly certain that on all of the variations, the bolt you mention can be replaced with a banjo. On the SS bikes (& other models) this banjo bolt is the same as those use on the head rocker feed. So try one of these for size and see if it lets oil pass through to the pump feed boss.

Phil, I have the timing cover shown in your second pic (pre 58) on my 99. The bolt refered to holds a spring loaded gauze filter to protect the pressure relief valve plunger, which is located inside the timing cover. Iâm not sure this could be replaced with a banjo bolt to successfully provide pressure feed to the head.

Regards, Tim

Phil, I have the timing cover shown in your second pic (pre 58) on my 99. The bolt refered to holds a spring loaded gauze filter to protect the pressure relief valve plunger, which is located inside the timing cover. Iâm not sure this could be replaced with a banjo bolt to successfully provide pressure feed to the head.

Regards, Tim

Hello banjo rocker feed pipe runs of the return oil pipe the fitting is just under the oil tank as a part of the oil tank union fitting the timing cover with the small single pressure relief valve was made from September 1959 and went on till Bracebridge street closed in October 1962 hope this puts some light on things

I am a little confused now................your diagram shows the inside of the 58 -62 cover. Attachment should be similar to your cover for an Atlas.

Converting to pressure rocker feed is easy with this cover.......you just replace the small bolt with a banjo and union. The benefit of this conversion is a constant oil feed to the rockers which quietens them down and it also helps to decrease spindle wear. Most post 1965 Big Norton Twins had a pressure rocker feed as standard. Pre- this time the feed (as Anna points out) is generally from the return side to the oil tank. It is often referred to as a low pressure return feed.

Now there is a downside to this conversion if your engine was an early Atlas with a low pressure feed to begin with. To make the conversion worthwhile you have to change several components. Firstly.....the pressure feed system saps a good amount of oil which ought to be keeping the big ends healthy. So you may need to have the double speed (6 start) gears/worm on the oil pump to keep the pressure up. Second....a pressure feed system does not work very well if the old scrolled rocker spindle are left in place. The oil just belts past these and then floods the head. You need spindles that are unscrolled. Usually referred to as plain. Finally....adding to the cost implication. Old scrolled rocker/spindles tend to have lots of wear in them both inside the rocker and the spindle (where you might find a step). Hence replacing them as a set is advised as best practice. The last time I equired about a conversion with all new parts the quote was £400 plus.

Hi Phil, sorry, I think it's me & my trusty steam driven computer getting confused, I had a bit of trouble opening your pictures, I clicked on the first one & nothing happened so I clicked on the second one & a picture opened so I assumed, wrongly, that I was looking at your second picture. What had actually happened was the first pic had opened but I didn't look at or read the title on the picture it's self. My Dommie was, according to NOC records, built Sept 15th 1957, but is a 1958 model year 99 with alternator & 18D2 distributor. I am the second owner & to the best of my knowledge, it is completely as it left Bracebridge street. It has what you describe as the 58-62 timing cover & rocker feed from the return at the tank, I know of at least two other twins from 1958 that have exactly this layout but I notice Anna states this type of cover ran from Sept 59-Oct 62, so yet more confusion.

Jonathan, The cover you show can have a banjo bolt in place of the blanking plug under the pressure relief valve to provide pressure rocker feed if necessary.

Regards, Tim

Hi Phil, sorry, I think it's me & my trusty steam driven computer getting confused, I had a bit of trouble opening your pictures, I clicked on the first one & nothing happened so I clicked on the second one & a picture opened so I assumed, wrongly, that I was looking at your second picture. What had actually happened was the first pic had opened but I didn't look at or read the title on the picture it's self. My Dommie was, according to NOC records, built Sept 15th 1957, but is a 1958 model year 99 with alternator & 18D2 distributor. I am the second owner & to the best of my knowledge, it is completely as it left Bracebridge street. It has what you describe as the 58-62 timing cover & rocker feed from the return at the tank, I know of at least two other twins from 1958 that have exactly this layout but I notice Anna states this type of cover ran from Sept 59-Oct 62, so yet more confusion.

Jonathan, The cover you show can have a banjo bolt in place of the blanking plug under the pressure relief valve to provide pressure rocker feed if necessary.

Regards, Tim

yours anna j

OK.........nearly there.

Jonathan's photo shows a well used post 1964 Atlas/SS type of timing cover. This had the vertical take-off for the rev counter and stopped all the complaints about scratched exhaust pipe chome and melted drive cables.

This type of cover was used to give a pressure feed to the rockers. But don't forget to check all the other bits that go with this set-up.