Navigator oil Pump

Hi Ulrich,
The Electra was the first Norton model to go to a 6 start pinion on oil pump. That would be late '63.

Why? Simple to do and might help in hotter climes like the southern USA. 

So why not do on all models? Which AMC did gradually, across the range. 

Not sure if the last Navigator of 1965 ever carried the 6 start pinion. I had one, but can' t remember that detail. 

Certainly, all lightweights with the later Electra type gearbox had a different engine breather, less convoluted and bigger diameter drilling. 

I think the biggest problems likely with a doubling of oil pump speed are with double the flow at cold. The pressure relief valve will have to spill twice the amount of cold oil, through narrow drillings that were never enlarged with the 6 start introduction. Lip seals on crank feed ends struggle. 

Suspect that oil pressures get a lot bigger on your autumnal European short ride. The lightweight oil tank seldom warms up much. 

Your observed oil leak, if from the head gasket, is likely from the four rocker box drains that go through the joint, through the cam follower bushes, into the crankcase. The pressure here is crankcase pressure, coming up the drains. 

Do you run with a solid copper head gasket? Mmmm.. 

I had a rocker oil feed manifold fail at a soldered joint and that took a bit of tracing. Looked like a gasket leak. 

Hope you get to the bottom of it. 

Peter 

I've fitted the 6 start oil pump drive to my Navigator.  I believe that when these were fitted to the big twins, in production, the oil ways were made bigger.  Therefore, I increased the size of the oil ways, don't remember the size increase but have a note of it.
As Peter says the problem is the pressure relief valve, that should have been given increased capacity.  I did just that, giving the valve considerable extra ability to pass oil.  I also lowered the "blow off" pressure, 45psi (as standard?) is unnecessarily high.  I described this in my wet-sumping article in "Roadholder". 

Hi Uli, 

The attached picture shows two washers. They are both required. Both are of greater diameter than the bush outside. 
They are of different inside diameter to fit as shown. 
Thanks to Andy Sochanik for the photo. 
The washers are of different thickness too. 
Part numbers on the photo. 
It appears you have not fitted these special washers. 

Peter

Hi all, I expect you already know but all Electras were built from the start with the six start oil pump and the later Navigators and Jubilees got them too from engine number 106838 onwards.   I have checked in the Lightweight Compendium which confirms this and my late Navigator and Electra both have the six start pump when I got them.   I have stripped and cleaned both oil relief valves and they seem identical to the earlier engines and share the same part number.   I can't comment on the size of the oil ways but I have managed to make both my bikes 99% oil tight so the more powerful pump doesn't seem to create any more oil leaks.   Finally both my bikes have spigot-less barrels and heads.   I have used NOS composite Jubillee head gaskets on both of them with a smear of good quality high temperature silicone sealant round both sides of the push rod tunnels which has cured the tendency to leak there.   With meticulous frequent torquing down of the heads I have also had no incidents of blown head gaskets.  (I hope I'm not tempting providence by saying that!!!). The added advantage of using Jubilee head gaskets is they are a better fit on spigotless heads and you can remove and replace one head and head gasket at a time unlike the original one peace head gasket and the new solid copper one.   

Sorry to hear about your gear box and oil leak problems Uli - good luck getting them fixed!  For what it's worth I only ever use NOS composite head gaskets - despite careful anealing and the use of silicone sealant I have not managed to get the solid copper ones to be oil tight.

I hope that is helpful!   Cheers Nick

This has been part of the RGM stock for quite a while. 

Not the place you might think of, but RGM are a responsive friend to Norton owners, and are brave enough to get stuff made. 

Lightweight kick-start anyone... 

Thank you RGM. 

Peter

Hi Peter, thanks for the top tip about RGM stocking composite head gaskets for the Navigator - I would never have guessed!   A very reasonable £10.90 ex VAT and in stock according to their website unlike the NOC shop sadly.   I have to admit I am not a fan of the solid copper head gaskets which in my experience always eventually weep oil round the push rod tunnels despite annealing and using silicone sealant and meticulously torquing down the heads.   Probably my incompetence but I have had far better results with the original gaskets.   Good luck Uli, let us know how your repairs go!  

Ulrich, the article appeared in the June 2025, No. 450 edition.