MK3 Timing Cover on Pre MK3 850

Yes, it fits fine.

They come as a kit, with all the required o-rings and seals.

https://andover-norton.co.uk/en/shop-details/16717/timing-cover-750-850-mk3-c-w-all-fittings

It is important that the oil pump washer is the bigger diameter, flatter one.

It does make a little bit of difference to the speed of wet sumping, but not as much as you’d hope.

We have a MKIII and a Combat engine both fitted with the MKIII timing cover. We also have two Dominator 650SS’s. All four engines were fitted with brand new oil pumps within the last three years. The Commando engines wet sump in three weeks The Dommie engines wet sump in two weeks. So you could conclude that the MKIII timing cover improves the speed of wet sumping by 50%.

Here is my 72 engine with the MKIII cover

It is well worth using the guide tool when you put a timing cover on - it will make sure you don’t damage the camshaft oil seal.

https://andover-norton.co.uk/en/shop-details/15621/guide-tool-camshaft-oil-seal

Wow thats a smart looking motor! Love the finned rockers (Dunstall?), been looking for these for a while but nothings turned up. I've not seen that mod to the rocker feed tho? Where is that from?

They are investment cast, and hand polished by Edward ‘Sir Eddy’ Billington-Smith who sadly passed away a few years ago.

To my knowledge he only made a few hundred sets.

He had some really interesting ideas around engineering, and getting the most out of a Norton twin which I found fascinating.

He was building his ultimate dream, and was planning to do some speed trials on the salt with the goal of breaking records, but unfortunately he passed away before he fulfilled his dream.

When he died, his family stepped up, and as a tribute to him, they carried on his work and made it to the salt.

https://youtu.be/Jj7KNnTpnlc

I have one fitted to my Mk IV 750. I bought it for the ability to access the cam chain and check the tension periodically without having to upset the timing by taking the cover off.

Regarding the anti-wetsump feature I  read somewhere that if you stick the bike in gear and rock it backwards it "sucks" the cap back against the oil pump seal instead of just relying on spring pressure. I have no idea if it's true though.

Look up on ebay Norton Finned Valve Cover Set, and they are there . In the USA being sold by bsanut. I've had two sets off him, really good quality like all the stuff he sells. No prob shipping to the UK.

The Bsanut/ Eurotrash Jambalaya set is not the same although they,re very nicely made as you say. Sir Eddies were sold out some time ago and have closer and thinner fins. Very good quality and were quite expensive but well worth it. I only have the three rocker covers preferring the my existing rocker spindle oil lines setup and the old Wassell partially finned ignition cover