Is This Part Of The AMR/Nortec Pressure Relief Valve Mod?

Last winter I left myself a "to do" note and now I'm trying to figure it out. It was with my oil pump and timing cover that AMR had modified and returned. I must have printed that photo, but I'm not sure where it came from. Maybe a forum post? I wrote the note, got the 1/4-20 set screws, then at some point completely dumped my memory. I'd rather not plug that case hole indicated by the white arrow without knowing for sure if it is actually part of the AMR/Nortec mod or if it possibly has to do with one of the case breather reed valve mods I am also trying to remember about. This is a '72 Combat engine I'm slowly rebuilding to standard Combat spec. Does anyone recognize that photo?

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pantah_good said:

Last winter I left myself a "to do" note and now I'm trying to figure it out. It was with my oil pump and timing cover that AMR had modified and returned. I must have printed that photo, but I'm not sure where it came from. Maybe a forum post? I wrote the note, got the 1/4-20 set screws, then at some point completely dumped my memory. I'd rather not plug that case hole indicated by the white arrow without knowing for sure if it is actually part of the AMR/Nortec mod or if it possibly has to do with one of the case breather reed valve mods I am also trying to remember about. This is a '72 Combat engine I'm slowly rebuilding to standard Combat spec. Does anyone recognize that photo?



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I wonder if thats why their fix never seemed to work on my '72...

Was this OPRV modification done (in addition to the usual Anti-wet sump valve mod.)?

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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.

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Although it states that the modification discharges the oil "directly into the sump" it should discharge it into the timing chest.

I'm sorry LAB, I'm not sure what you mean there. I just sent out the oil pump and timing cover to AMR to get worked on.

pantah_good said:

I'm sorry LAB, I'm not sure what you mean there. I just sent out the oil pump and timing cover to AMR to get worked on.

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The usual AMR modification is to add an anti-drain (ball) valve to the timing cover, but it seems they also modify the OPRV to vent into the timing chest.

Yes, he added the spring loaded ball in the timing cover.

Do you mean by "modify the OPRV to vent into the timing chest" - locktiting the 1/4-20 set screw plug into the hole shown in the photo with the white arrow?

pantah_good said:

Yes, he added the spring loaded ball in the timing cover.

Do you mean by "modify the OPRV to vent into the timing chest" - locktiting the 1/4-20 set screw plug into the hole shown in the photo with the white arrow?

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No, blanking off the oil gallery isn't the actual modification.

The gallery should only be plugged IF the OPRV modification has been done.

Sorry for being so dense - I keep rereading the Nortec mod paragraph but I can't figure out how to tell if the mod was ever done.

pantah_good said:

Sorry for being so dense - I keep rereading the Nortec mod paragraph but I can't figure out how to tell if the mod was ever done.

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You'd have to either ask AMR or preferably, take the cover off and see if it's been modified to vent into the timing chest.

The picture you submitted is my modification. The timing cover is also modified as recommended by Jim Comstock and dynodave. What I did is drill a hole in the timing cover so that the oil pressure relief valve oil dumps into the timing chest area instead of the oil recirculating to the inlet side of the oil pump. This is the way pre-Commando and 850 Mark III's are plumbed. I didn't drill the timing cover just like the 850 Mark III because it would have needed a drilling jig that I didn't have. If I was AMR I would have come up with a drilling jig. I then plugged the other relief valve outlet in order to make the timing cover Murphy proof. That way you wouldn't have to use set screws to plug the oil port in the engine case.

Here is the location where I drilled the timing cover:



Here is where I used two 1/4-20 set screws one tightened on top of the other using Loctite:






Here is my original post thread. No thanks to Photobucket some pictures are missing:
https://www.accessnorton.com/Norton...sure-relief-valve-and-amr-modification.18868/


I really put the AMR mod and my modification to the test. It has been a little over a year since I started my motorcycle and the engine has STILL not wet sumped. The reason I haven't started my bike in such a long time is that I severed my right Achilles tendon last January. After two surgeries I am still recovering.

If you have any questions let me know.

Peter Joe

Thank you Peter Joe. No, my timing cover does not have that additional angled drilling that you are pointing to in your first picture. That must be the $20 charge mentioned in the AMR web site, which I didn't ask for due to not knowing any better. So as I understand it, and as my timing cover is right now, I do not want to plug the case hole like you show in your second picture. But, how important is it to do that additional step? I'm a little leery of drilling on an angle like that myself, but now might be the time to send to cover back to AMR if that additional step is really worthwhile.

I didn't realize that AMR now offers the option of drilling the timing cover and supplying the Allen screw that goes into the threaded oil port of the engine case. I don't think that option was offered when I had my timing cover modified. Interesting!

If your timing cover has not been modified like mine, you definitely do not want to plug that threaded port in the engine case. Otherwise your oil pressure relief valve wouldn't work at all.

As to whether or not the additional mod is necessary or not, it's up to you. As a test you can install the timing cover without that set screw, leave the oil line that feeds the head off and let the bike sit that way for a few days. If oil continually drools out through the port where the oil line attaches, it's a good sign that it is leaking past the oil pressure relief valve.

Peter Joe

Thanks again, I will run an email by AMR, but I'm tempted to leave things as they are, at least for now. That mod could be done most any time down the road by taking the timing cover off.

PeterJoe said:

I didn't realize that AMR now offers the option of drilling the timing cover and supplying the Allen screw that goes into the threaded oil port of the engine case. I don't think that option was offered when I had my timing cover modified. Interesting!

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Actually, after now looking thru my original email to AMR, I had inquired about that about a year ago before I sent my parts out. This was Mike's reply, and now I (finally!) understand why I didn't have that done:

"In regards to the pressure-relief valve modification, I am going to take a pass on that for now, until I can do some more research. In my nearly twenty years of doing the Nortec mod, I have had less than a hand-full of issues with the pressure-relief valve. Modifying the pressure-relief valve discharge location is basically going back to the Atlas and earlier configuration, which to my memory was not an issue at the time. I really don't know why Norton changed the discharge location on the 1972 and later models, but it obviously created more problems than it solved. I am considering a possible bench-test scenario where I could mount the customers timing cover w/pressure relief valve and the oil pump to the appropriate Commando engine case to monitor any oil leakage past the pressure relief valve in a static test. I am going to have to think this over, as it won't necessarily apply or be needed by every Commando engine."

I sent my pump and cover to AMR for modification over a year ago, also got one of Matt's (CNW) reed breathers.
My engine is still apart due to other projects (and a broken neck, but that's another story). I just checked, and my cover didn't get this mod, and I don't believe it was offered at the time.

Glad you posted this as my engine is just going together now. Will try the cover as is and if there are still problems, will drill the cover as suggested and block the oil portal.
JUG

pantah_good said:

Actually, after now looking thru my original email to AMR, I had inquired about that about a year ago before I sent my parts out. This was Mike's reply, and now I (finally!) understand why I didn't have that done:

"In regards to the pressure-relief valve modification, I am going to take a pass on that for now, until I can do some more research. In my nearly twenty years of doing the Nortec mod, I have had less than a hand-full of issues with the pressure-relief valve. Modifying the pressure-relief valve discharge location is basically going back to the Atlas and earlier configuration, which to my memory was not an issue at the time. I really don't know why Norton changed the discharge location on the 1972 and later models, but it obviously created more problems than it solved. I am considering a possible bench-test scenario where I could mount the customers timing cover w/pressure relief valve and the oil pump to the appropriate Commando engine case to monitor any oil leakage past the pressure relief valve in a static test. I am going to have to think this over, as it won't necessarily apply or be needed by every Commando engine."

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Hi Buddy, just wondering what you ended up finding out about the timing cover mod. As I stated in the last post, the question of the timing cover mod never came up when my bits were sent to them for modification. Your post was the first I heard about it.
jug

Funny you should mention this today. Today I made the jig to machine the timing covers for the same "AMR" modification for my own use of course. I also made a simulated oil pump which bolts to the cover so I can check how much oil pressure is required to lift the
ball off the seat. I've come to a stand still now until some more parts arrive, digital oil pressure gauge etc.

pantah_good said:

This was Mike's reply, and now I (finally!) understand why I didn't have that done:

"snip
. Modifying the pressure-relief valve discharge location is basically going back to the Atlas and earlier configuration, which to my memory was not an issue at the time. I really don't know why Norton changed the discharge location on the 1972 and later models, but it obviously created more problems than it solved.

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Here is the atlas cover.
No return to case.
Vent on top of OPV into timing chest, out of easy view, to the right of the grub screw plug, only light shadow visable


Here is the 1968 (not 72) first commando (twin chain) timing cover with the OPV return into engine case. oil vent methodilogy (only) unchanged through 74.
see my page here for the majority of the NHT covers like the 1975 mkiii
http://atlanticgreen.com/NHTtimcvr.htm

Excellent resource Dave. My present project is clear but in future I will have to sort through a mound of loosely identified engine parts from '64 to '71. Thanks for what you're doing.

jug said:

Hi Buddy, just wondering what you ended up finding out about the timing cover mod. As I stated in the last post, the question of the timing cover mod never came up when my bits were sent to them for modification. Your post was the first I heard about it.
jug

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Hi Jug, what I've found out is all in this thread, a lot of which I'm not sure I still fully understand. Coincidentally, yesterday I passed along my Norton project to other hands, so I don't have any parts here any more to look at. I'll try and explain more about that soon in the bikes rebuild thread. But, as best as I remember, I left the cover unmodified.
Bill