AMR Nortec Mod

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PeterJoe said:
Yes I did take the oil pump apart to check. What had happened is that I installed the oil pump with the ball valve temporarily installed using a makeshift bracket. I observed oil leaks coming out of the oil pump's end plates. So I dismantled the oil pump, resurfaced the end plates, reassembled and checked again and the oil leaks were reduced dramatically.

Here is a picture of my oil pump with the temporarily installed ball valve.

AMR Nortec Mod




Peter Joe
Click to expand...
How did you spin the engine to test the oil flow? Just by kicking it over?
 
Copied from his website...
"This involves the installation of a check ball in the timing cover at the point at which the oil pump feed bush contacts the cover.

This essentially prevents oil from passing through the gears of the pump and draining the oil tank into the engine sump while the bike is parked, a common problem on all Norton twins.

Additionally, two o-ring seals are installed inside the pump to prevent oil from passing between the feed and return sides which also can contribute to wetsumping."

Does not mention resurfacing pump surfaces.
 
rvich said:
Are you considering the Pressure Relief Valve modification as well?

I understand that oil can leak past the PRV, but I have to admit that moving the discharge directly to the sump to prevent wet sumping has always been confusing to me. I'd enjoy it if someone could clear that up. Or is it that I have misunderstood what they are proposing with this modification?

Click to expand...
The oil pressure relief valve modification mimics the pre-Commando engines lubrication system and also the 850 Mark 3 lubrication system. The modification isn't breaking any new ground. The modification basically plugs the threaded pressure relief hole in the crank case (thereby preventing wet sumping in that area) and then drilling the timing cover so that the pressure relief valve's discharge oil is redirected into the timing chest area.

Peter Joe
 
PeterJoe said:
I didn't spin the engine over to check the oil flow. This was a check to see where leaks can happen that would cause rapid wet sumping.
Peter Joe
Click to expand...
So you are saying that in a STATIC state, you had oil leakage past the stationary oil pump end plate from the oil pump body? That's pretty knackered!
 
grandpaul said:
So you are saying that in a STATIC state, you had oil leakage past the stationary oil pump end plate from the oil pump body? That's pretty knackered!
Click to expand...
Yes, that's an excellent source of wet sumping and the way Norton made it! Maybe it's a design feature...

Anyway, after I got the oil pump sorted and the pressure relief mod done I gave the AMR mod a real test by being laid up for 18 months recovering from an Achilles tendon surgery in my right foot in 2017. After 18 months the motorcycle still had not wet sumped.

Peter Joe
 
PeterJoe said:
I didn't spin the engine over to check the oil flow. This was a check to see where leaks can happen that would cause rapid wet sumping.

Peter Joe
Click to expand...
Nice job on doing that. Most people wouldn't think to check it like that.
 
PeterJoe said:
... being laid up for 18 months recovering from an Achilles tendon surgery in my right foot...
Click to expand...
Yikes!

I'm concerned about my right leg being able to kickstart again next month (still in an AirCast boot), because there was a dislocated tendon (along with the broken Fibula); it wasn't the Achilles, thankfully...
 
Guys, help me out here. How does the OPVR mod into the timing chest assist in the prevention of wet sump?
Now if it gets past the OPVR, it drains into the TC, then into the sump. Even faster if the return has been relocated to the bottom.
Still goes into the sump. What am I missing?

Is there another performance reason to vent to the chest vs, the sump?
 
MichaelB said:
Guys, help me out here. How does the OPVR mod into the timing chest assist in the prevention of wet sump?
Now if it gets past the OPVR, it drains into the TC, then into the sump. Even faster if the return has been relocated to the bottom.
Still goes into the sump. What am I missing?

Is there another performance reason to vent to the chest vs, the sump?
Click to expand...

This is the PR oil path.
The passage circled in red corresponds with a hole drilled in the engine case.
That hole goes (T's into) to the passage that is the incoming oil from the oil tank. (On engines that have that set up)

By blocking the hole in the engine case (and machining some form of channel in the timing cover for the PR oil to bleed off) there can be no possible leakage from sitting/storage from that oil feed passage (back flow) past the PR thread (I doubt it would get past the PR shuttle/piston back to that area/cavity where the pump outlet is. (bypassing the check ball and spring as per the other modification)

Would oil get past the PR thread as back flow ?
I think it is just a safeguard mod for the other one (check ball)

cvr.jpg
 
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MichaelB said:
Guys, help me out here. How does the OPVR mod into the timing chest assist in the prevention of wet sump?
Now if it gets past the OPVR, it drains into the TC, then into the sump. Even faster if the return has been relocated to the bottom.
Still goes into the sump. What am I missing?

Is there another performance reason to vent to the chest vs, the sump?
Click to expand...
I think it's the way AMR words it.

This modification applies to the Norton Commando models through 1974 that from the factory, had the discharge point of the pressure relief valve relocated from directly into the sump, as was the case with the previous Atlas and Dominator models and the later MK3’s, to the feed line from the oil tank. This allowed in many cases, oil to pass through the pressure relief valve in the timing cover, into the sump when the engine was not running, thereby adding to the wet-sumping problem. Our modification places the discharge point back to its original point, directly into the sump, and requires that the oilway from the feed line in the engine case be plugged with a set-screw that we can supply. It is recommended that the threads in the case be cleaned with a degreasing agent such as carburetor or brake cleaner, and then a quality thread-locking compound such as “Loctite” be applied to the screw. The screw should be threaded in to below flush with the gasket surface, so as not to interfere with the sealing of the timing cover.
Click to expand...
I believe the underlined sentence is unclear and poorly written.

For the Commandos (except Mk3) when the oil pressure regulator is activated will drain the oil directly to the sump. I can sort of see why the factory did that, that "excess oil" would be picked up by the pump and pushed back to the tank.

But if the assumption is that oil can leak past the OPRV when the engine is static and adds to the wetsumping by going straight into the sump. If it has to go to the timing case (even with relocated holes) it will prevent some (not a lot, maybe a cup?) of oil from getting to the sump. That might buy a user a week or two assuming oil is getting past the OPRV.

I don't think it's a cure but another bandaid.
 
Here's a shot of a spare cover I have.
The bottom relief in the back is the pressurized feed, the side hole is the dump.
IMG_5541.JPG

It has to get past the OPVR, maybe 3 or 4 threads, then out to the sump.
Vented to the top, into the TC, longer path to the sump.
I'll accept it's not a cure, but a slowing down / bandaid.

Not sure how much oil blows off when these release, is the TC a better spot to release vs the CC?
 
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Taking another look at the inside of the cover.
IMG_5542.JPG

Relocating it to the top of the OPVR puts it well above the flow line of the crank.
What ever leaks past the pump, will drain into the crank.
I have to say the existing discharge is also above the crank in the tilted Commando position.
Not really sure how it can back up and leak through the OPVR.
In the horizontal Atlas, it is fairly level.

I believe I have read elsewhere this is a recommended mod. Is there another performance reason?
 
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AMR:
This allowed in many cases, oil to pass through the pressure relief valve in the timing cover, into the sump when the engine was not running,
Click to expand...


That should be: "...allows oil to pass through the pressure relief valve into the timing cover crank feed gallery from where it can drain through the crankshaft to the sump when the engine is not running.".


swooshdave said:
But if the assumption is that oil can leak past the OPRV when the engine is static and adds to the wetsumping by going straight into the sump. If it has to go to the timing case (even with relocated holes) it will prevent some (not a lot, maybe a cup?) of oil from getting to the sump. That might buy a user a week or two assuming oil is getting past the OPRV.
Click to expand...

With the "Mk3" modification NO OIL can pass through the OPRV (unless it has gone through the pump and got past the anti-drain valve first) because the 'OPRV' return drilling to the 'pump feed' is blanked off so there can be no static drain.
 
Time Warp said:
If CC is crankcase, the PR vents into the incoming oil line feed.
Click to expand...
Ahhh, Ok. I see that now.
I thought it was blowing off into the CC, crankcase.
So, the pressurized oil is blowing off into the feed of the pressure causing item, the pump.
Doesn't seem very efficient.

That appears to be a GOOD reason to reroute it.
Not so sure about the wet sumping as it just drips back into the pump on the original dump.
 
Last edited:
This modification applies to the Norton Commando models through 1974 that from the factory, had the discharge point of the pressure relief valve relocated from directly into the sump, as was the case with the previous Atlas and Dominator models and the later MK3’s, to the feed line from the oil tank. This allowed in many cases, oil to pass through the pressure relief valve in the timing cover, into the sump when the engine was not running, thereby adding to the wet-sumping problem. Our modification places the discharge point back to its original point, directly into the sump, and requires that the oilway from the feed line in the engine case be plugged with a set-screw that we can supply. It is recommended that the threads in the case be cleaned with a degreasing agent such as carburetor or brake cleaner, and then a quality thread-locking compound such as “Loctite” be applied to the screw. The screw should be threaded in to below flush with the gasket surface, so as not to interfere with the sealing of the timing cover.
Click to expand...

I cannot believe how confusing this description is.
 
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