AMR will be closed for our summer break from July 21 through August 11, 2025
Nortec Anti-Wet Sump Modification
Brought to you by: AMR
16936 S Mann Ave
Sahuarita, AZ 85629
Phone: 520-303-4394
Toll Free: 800-849-6970
10am-5pm Tuesday – Friday MST
Nortec Anti Wet Sump Information
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 wet-sumping.
Procedure – Cover: The cover is checked in and inspected, then machined to accept the spring and check-ball. At that time, we generally do the PRV mod (see below), which is recommended for all pre-MK3 Commandos. Pump: The pump is tested for leakage when checked in, and then disassembled and inspected for damage and wear. Note: Any significant damage to the gears or pump body on the feed side will disqualify the pump for future use. Some minor scoring of the pump body and/or minor damage to the gear teeth on the return side can be tolerated up to a point. Consultation with the customer will be required in these cases. Once the machining is completed, the pump will be reassembled and tested again for leakage on our in-situ test stand.
The charge for this service is $100 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 timing case/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 timing case/sump, and requires that the oilway from the feed line in the engine case be plugged with a set-screw which we 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-wet-sump 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.
What you need to send us
We will need your clean, oil free timing cover and your assembled oil pump. On Mk III models only, please include the existing check valve spring, unless you want to buy a new one.
The oil pump should be packaged in a sealable plastic bag or other protective wrapping to avoid oil contamination of the packaging material. Please package the cover and pump so that they are protected against damage from moving around in the package. We will email you when your package arrives, and once again when the work is completed with the total for your PayPal payment. Please include your phone number, email address and shipping address in the note you include in your package. It would be much appreciated if you could also add to that the year, model and if available, the serial # of the engine that the pump and cover came from.
*We also recommend that the timing cover crankshaft and camshaft seals be replaced at the same time, along with a new pump and timing cover gaskets. We also offer all related gaskets and seals for sale. If the timing cover seals are purchased through AMR the seals will be installed at no additional cost. Please include your list of added parts, if needed, with your shipment.
Turn-around time is two weeks. This does NOT include shipping time.
What you will receive
Your return shipment will include: your modified oil pump and timing cover ready to install; installation instruction sheet for the pump and cover, with a spare feed-bush seal; instruction sheet for installation of the set screw to the engine case with attached set screw, any extra parts that you have ordered and your itemized receipt.
Payment
Method of payment is PayPal. The total will be determined after work is completed and return shipping calculated. We will email you with the total and our PayPal address once the work is completed. Your package will be shipped once payment is received. Return shipping will be via Priority Mail.
Last Updated: July 1, 2025
AMR will be closed for our summer break from July 21 through August 11, 2025
Nortec Anti-Wet Sump Modification
Brought to you by: AMR
16936 S Mann Ave
Sahuarita, AZ 85629
Phone: 520-303-4394
Toll Free: 800-849-6970
10am-5pm Tuesday – Friday MST
Nortec Anti Wet Sump Information
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 wet-sumping.
Procedure – Cover: The cover is checked in and inspected, then machined to accept the spring and check-ball. At that time, we generally do the PRV mod (see below), which is recommended for all pre-MK3 Commandos. Pump: The pump is tested for leakage when checked in, and then disassembled and inspected for damage and wear. Note: Any significant damage to the gears or pump body on the feed side will disqualify the pump for future use. Some minor scoring of the pump body and/or minor damage to the gear teeth on the return side can be tolerated up to a point. Consultation with the customer will be required in these cases. Once the machining is completed, the pump will be reassembled and tested again for leakage on our in-situ test stand.
The charge for this service is $100 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 timing case/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 timing case/sump, and requires that the oilway from the feed line in the engine case be plugged with a set-screw which we 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-wet-sump 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.
What you need to send us
We will need your clean, oil free timing cover and your assembled oil pump. On Mk III models only, please include the existing check valve spring, unless you want to buy a new one.
The oil pump should be packaged in a sealable plastic bag or other protective wrapping to avoid oil contamination of the packaging material. Please package the cover and pump so that they are protected against damage from moving around in the package. We will email you when your package arrives, and once again when the work is completed with the total for your PayPal payment. Please include your phone number, email address and shipping address in the note you include in your package. It would be much appreciated if you could also add to that the year, model and if available, the serial # of the engine that the pump and cover came from.
*We also recommend that the timing cover crankshaft and camshaft seals be replaced at the same time, along with a new pump and timing cover gaskets. We also offer all related gaskets and seals for sale. If the timing cover seals are purchased through AMR the seals will be installed at no additional cost. Please include your list of added parts, if needed, with your shipment.
Turn-around time is two weeks. This does NOT include shipping time.
What you will receive
Your return shipment will include: your modified oil pump and timing cover ready to install; installation instruction sheet for the pump and cover, with a spare feed-bush seal; instruction sheet for installation of the set screw to the engine case with attached set screw, any extra parts that you have ordered and your itemized receipt.
Payment
Method of payment is PayPal. The total will be determined after work is completed and return shipping calculated. We will email you with the total and our PayPal address once the work is completed. Your package will be shipped once payment is received. Return shipping will be via Priority Mail.
Last Updated: July 1, 2025