AMR Nortec Mod

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I know this has been covered before in places like this. https://www.accessnorton.com/Norton...e-amr-nortec-pressure-relief-valve-mod.24205/


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.

The charge for this service is $80 plus shipping.

This includes machine work, check ball and spring and a special oil pump feed bush seal, as well as the internal pump seals.

Nortec Pressure Relief Valve Modification​

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.

The cost of this service is $20, and can be done at the same time that the Nortec anti-wetsump valve modification is done. As stated above, we will supply the set-screw along with a sketch and instructions for its installation. Please indicate in the note with your timing cover and oil pump shipment whether or not you would like us to perform this additional service.

But I haven't seen anything recently. I reached out to AMR and they are still doing the modifications. My brother had the mods done about a year ago and is very happy with the results. His bike use to wetsump overnight. He's still wetsumping but it takes weeks. I'm hoping it eliminates mine altogether.

On my 850 after a week or two I have to kick the engine over a bunch (spark plugs out help to clear the crankcase enough to get it to start. I have the Comstock sump filter reed breather that assists with clearing the sump. But I want to try the AMR fix too.

Since the bike is up for winter updates I started the bike (had to clear the oil first from the crankcase) and then when I shut it off I blocked the oil line. This should help slow the oil from the oil tank.

zuyeqgs.jpg


Next I popped off the timing cover and oil pump.

zf7GZ0E.jpg


I hope to get the parts shipped off to AMR this week.

XfMKMub.jpg


The crankshaft and camshaft seals aren't very old but I'll replace them anyways. And I'll get all new gaskets. Anything else I should do while I'm in here?
 
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grandpaul

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Sure,

-Needle roller cam bearing
-Cam replacement window
-Adjustable cam sprocket
-Megacycle 560-00 cam
-Radiused (by Megacycle) cam followers
-JE dished pistons with Total Seal gapless rings
-Maney cases
-Maney crank
-Beefy rods
-FullAuto head (forgot what they're called now), ported
-Oversize valves
-FCRs set up for all of the above
-TTI 5-speed box
-Monoshock rear end
-VR880 bodywork
-Viking black chrome exhaust
-Excel shouldered allow wheels w/ stainless spokes from Buchanans
-ARD micro magneto

I'm sure I'm missing 28 or 34 other nice upgrades...
 
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Sure,

-Needle roller cam bearing
-Cam replacement window
-Adjustable cam sprocket
-Megacycle 560-00 cam
-Radiused (by Megacycle) cam followers
-JE dished pistons with Total Seal gapless rings
-Maney cases
-Maney crank
-Beefy rods
-FullAuto head (forgot what they're called now), ported
-Oversize valves
-FCRs set up for all of the above
-TTI 5-speed box
-Monoshock rear end
-VR880 bodywork
-Viking black chrome exhaust
-Excel shouldered allow wheels w/ stainless spokes from Buchanans
-ARD micro magneto

I'm sure I'm missing 28 or 34 other nice upgrades...
I do want to put some of the rims on one of these days. But really, I don't think anything on your list can be accomplished with just the timing cover off.
 
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"Anything else I should do while I'm in here?"
Before you send your oil pump out for modification, I would dismantle it and sand the end plates of the oil pump smooth using a surface table or plate of glass. From the factory those end plates have pretty deep scratch marks which encourage oil leaks.

I would also remove the crank case drain plugs and then clean out the oil passageways of the oil pump. Leave the large plug off for now.

After you receive the modified oil pump, install the oil pump with a fabricated bracket that would hold the spring and ball valve up to the oil pump outlet. Next install the oil plug into the oil pressure relief valve port in the crankcase. Then go ahead and hook up your oil inlet line and see if there is any oil leakage that would cause wet sumping. You shouldn't see any oil leaking past the ball valve, very little oil seepage past the oil pump's end plates. You shouldn't see any leakage past the oil pressure relief valve bypass port plug and you shouldn't see any oil drooling down from the large crankcase drain opening. Heck I would let it sit for a couple of days like this before installing the timing cover to see what kind of wet sumping you might get.

Also you might want to check your timing chain tension.

Peter Joe
 
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Before you send your oil pump out for modification, I would dismantle it and sand the end plates of the oil pump smooth using a surface table or plate of glass. From the factory those end plates have pretty deep scratch marks which encourage oil leaks.

I would also remove the crank case drain plugs and then clean out the oil passageways of the oil pump. Leave the large plug off for now.

After you receive the modified oil pump, install the oil pump with a fabricated bracket that would hold the spring and ball valve up to the oil pump outlet. Next install the oil plug into the oil pressure relief valve port in the crankcase. Then go ahead and hook up your oil inlet line and see if there is any oil leakage that would cause wet sumping. You shouldn't see any oil leaking past the ball valve, very little oil seepage past the oil pump's end plates. You shouldn't see any leakage past the oil pressure relief valve bypass port plug and you shouldn't see any oil drooling down from the large crankcase drain opening. Heck I would let it sit for a couple of days like this before installing the timing cover to see what kind of wet sumping you might get.

Also you might want to check your timing chain tension.

Peter Joe

I assume when they modify the oil pump they do the resurfacing too?
 
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I do want to put some of the rims on one of these days. But really, I don't think anything on your list can be accomplished with just the timing cover off.
That's a super list. You could fit Jason the Chain Man IWIS timing chain.
 

rvich

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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?

 
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I made this rough animation showing the oil flow on the stock system prior to the AMR mod. Give me some feedback if I got something wrong. I'll do a more extensive one at some point with both the stock and modded systems. And I think I need to include the actual oil pump too.


It's based on this factory drawing,

oillines.jpg
 
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feedback?
15 seconds?
extremely rough
extremely incomplete

A complete discussion would also describe the progression of all NHT versions other wise only a low level of understanding, for one stage of NHT progression like your combat, will be understood. This is evidenced by questions unanswered by lack of engine model evolution descriptions.
A complete beginning description would show EVERY oil passage both intended AND unintended.

The modification is to address solving unintended oil passages.
 

grandpaul

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I think showing the transmission lube in that illustration was a silly idea. Some yokel is going to think it is supplied at one of the sump plug drain holes...
 
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feedback?
15 seconds?
extremely rough
extremely incomplete

A complete discussion would also describe the progression of all NHT versions other wise only a low level of understanding, for one stage of NHT progression like your combat, will be understood. This is evidenced by questions unanswered by lack of engine model evolution descriptions.
A complete beginning description would show EVERY oil passage both intended AND unintended.

The modification is to address solving unintended oil passages.
I should have been more clear, I wasn’t trying to describe the entire oiling system, just the pump and timing cover areas in regards to the AMR mod. I know several people have questions about what it actually does so I thought I’d try to show it more clearly.

I’m not going to make a six hour documentary describing every evolution in the oiling of the Norton big twin.

But since you didn’t point out any errors in this preliminary animation I feel good that it’s technically correct.
 

grandpaul

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And what happens once the red and blue oils mix?

Don't tell me, it all turns purple...
 
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So you took it apart to check?
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.

GEDC1074.jpg




Peter Joe
 
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