Norton Engine, Gearbox, Oil Tank Sump Plugs: All Types - Pre and Post War and Racing Type (Each)

Product no.: 1101 SumpPlugs

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This is a 'Variable' Listing, showing various types of Norton sump plugs - as were fitted to most Norton models from the 1920's through to the 1950's, both engine and gearbox, and also some additional 'Racing' type, either drilled for Lockwire and even a couple 'Wasted' for weight saving.  All are modelled on original Norton sump plugs - with all major dimensions replicated .  Price is Each - but also includes the sump plug washer.  We also sell the various washer types serperately.  See the table below for details and fitting for each sump plug type we offer

All our sump plugs are CNC manufactured by ourselves to original dimensions, using original patterns as examples - and trial fitted to original crankcase and gearbox castings of various single cylinder models.  All 1/4" BSP sump plugs (i.e. 1011_1 to 1011_10) are manufactured in brass, just as original Norton sump plugs were - then satin nickel plated (also the most common original finish).  As well as replicating the original different designs manufactured over a 30 year period - they also look extremely pretty.  For most of the brass type sump plugs - we have also held back a few in bare brass - which was also an original Norton finish - but these are limited.

By default for items 1101_1 to 1101_10 - we will send a satin nickel plated sump plug - state when placing online order in the comment section if you require a brass version instead (if available)

Note also that many OHV and SV oil tanks were also fitted with 1/4" BSP Drain/Sump Plugs - often listed as part number E3336, where the head shape was often similar to our 1101_1 or 1102_2 - the second of these being a lockwired version, which is a useful addition on any oil tank.  Ensure your oil tank sump plug thread is actually 1/4" BSP before fitting though, but if so, any of our brass 1/4" BSP plugs should fit (note - many SOHC oil tanks did not have drain plugs fitted) 

Also the Norton 'Oilbath' Chaincase also used an E3336 sump plug - I have seen both plain head and slotted variety fitted to the chaincase in the past.  And of course a lockwired version is very useful if you are intending taking your roadbike on a Track parade.

Which Plug: 1/4" BSP, 1/8" BSP or another thread type?? - Different sump plug fittings:  It is worth noting that the first 10 sump plugs are all 1/4"BSP threads, which was by the far the most common fitting for gearbox and oil tanks and for engine sump plugs up to 1948.  However many Post 1948 Norton single cylinder (and other model) crankcases were instead fitted with a smaller thread sump plug thereafter - which was normally 1/8"BSP.  Most of these engines are identifiable from earlier engines, because the sump plug was mounted under the crankcase, rather than at the side, and there was often an additional casting ramp in front of the hole, to stop the sump plug being pulled out if the bike was 'grounded'. 

We have replicated this later Post 48 Sump plug as well - see items 1101_11 and 1101_12 (locwired version).  An original 1/8" Norton sump plug was again used as a template, which we have CNC replicated exactly - other than ours are manufactured in stainless steel, rather than the original plated steel material that original 1/8"BSP were made in - so ours will not rust. 

It is important that you check your fitting before ordering though - particularly if you have a Post 48 model - because the original 1/8"BSP plug used a very fine thread, and the sump alloy was not very thick . . . it is very common to find that the crankcase may have stripped its thread in the past and been fitted with a different - slightly larger thread.  I have found the most common 'larger' thread is 7/16" BSF (and I have a couple of crankcasses in my own collection since the 1960's that have had this done) . . . so because of this we have also manufactured a Post 48 sump plug - but with 7/16" BSF thread - Item 1101_13.  I have talked to other highly experienced Norton engine builders and they also confirm stripped threads on later engines is a common occurrence.  Please satisfy yourself which thread you require before ordering

 

 

Types Available are as Follows:

Note: I have desctribed below the different variations, and wherever possible - the most common fitment of each . . . to the best of my knowledge from having stripped various original engine and gearbox's over the last 40 years, as well as talking to friends and customers where necessary.  However, providing thread and fitment is correct - you may find these plugs styles also fitted to other models, or different to below:

ID Type Thread Attributes Normal Fitment?
1101_1 - Shallow Curved 1/4" BSP

- Norton Shallow/Curved Type

- Satin Nickel Plated Brass (some brass unplated may also be available)

- Supplied with 1/4" BSP Dowty seal

- Referred to as E3336 in Spare Parts Catalog

- Normally seen fitted to Norton road model Gearboxs , both Pre-war and Postwar

- I have also seen this type fitted to OHV and SV engines, late 1930s to mid 1950's

- This type has a shallow hex head with a distinctive 'Norton' type curve to the head

- Ours are identical to the original item, including depth of groove for washer, and slight undercut to avoid hex digging in to casting.  In one of the photos can be a seen a genuine 'New Old Stock' Norton item (plated item on the right in photo), used as the pattern for ours 

1101_2

-Shallow Curved

- Lockwire

1/4" BSP

- Norton Shallow/Curved Type

- Satin Nickel Plated Brass (some brass unplated may also be available)

- Drilled through head to take lockwire

- Supplied with 1/4" BSP Dowty seal

- As above

- This type is drilled for lockwire - normally found on competition type gearbox's and engines

- Essential fitment if taking your bike onto a track event

1101_3

Shawllow Curved

- Slotted

1/4" BSP

- Norton Shallow/Curved Type

- Satin Nickel Plated Brass (some brass unplated may also be available)

- Slotted for Screwdriver

- Supplied with 1/4" BSP Dowty seal

As 1101_1 but slotted for a screwdriver

- I have seen these fitted to both gearbox's and pre-48 eingines

- Seem most common on late 1930's - 1948 engines for road going models - SOHC/OHV/SV, as the slot was more accessable for a screwdriver on sump of crankcase, when plug at side of sump

1101_4

Shallow Curved

- -Slotted

- Lockwire

1/4" BSP

- Norton Shallow/Curved Type

- Satin Nickel Plated Brass (some brass unplated may also be available)

- Slotted for Screwdriver

- Drilled for Lockwire

- Supplied with 1/4" BSP Dowty seal

As 1101_3 above, but these are also drilled for lockwire

- Normally fitted to competition bitkes, but very useful for ensuring it does not come loose and lose oil on road bikes

- Essential fitment if taking your bike onto a track event

1101_5

- Shallow Curved

- Lockwire

- Reduced Weight

1/4" BSP

- Norton Shallow/Curved Type

- Satin Nickel Plated Brass (some brass unplated may also be available)

- Drilled for Lockwire

- Centre bored and head shaped to reduce weight 

- Supplied with 1/4" BSP Dowty seal

- This sump plug starts off as the Shallow Curved type - as seen on most gearboxs and pre-48 engines, however for these - as well as drilling them for lockwire, we also bore the centre, and shape the head profile to reduce weight

- Although rarely seen on production bikes out of the factory, it was a normal thing for the serious 'Tuners' to do on a competition bike - as they are noticeably lighter than standard

- I will also be the first to admit - they look very pretty and are a 'focal point' on any competition bike - for that extra bit of Bullshit!

1101_6

Norton Deep Head Type

- Slotted

1/4" BSP

- Norton Deeper head /shallower Curve (Pre-War) Engine Type

- Satin Nickel Plated Brass (some brass unplated may also be available)

- Slotted for Screwdriver

- Supplied with 1/4" BSP Dowty seal

This sump plug is similar to the 'shallow curve' type above, but has a slightly deeper Hex, and the 'Norton' type curve is less pronounced than the type above

- Although not definitive - I have normally found this 'deeper head' type fitted to Pre-War models of all types = i.e. SOHC, OHV and SV models

- I cannot be sure when this type of sump plug was first fitted - but I know that customrs with engines as early as 1930 have provided me examples of this type fitted to their engines 

- May have been fitted to 1920's models - but have not had this confirmed yet (please email me if you a 20's model - and can update listing, thx!)

1101_7

Norton Deep Head Type

- Slotted

-Lockwire

1/4" BSP

- Norton Deeper head /shallower Curve (Pre-War) Engine Type

- Satin Nickel Plated Brass (some brass unplated may also be available)

- Slotted for Screwdriver

- Drilled for Lockwire

- Supplied with 1/4" BSP Dowty seal

This plug is the same as 1101_6 above, but this version, as well as being slotted, is also drilled for lockwire

- This type would normally be found on the engines of Pre-1948 SOHC models - particularly competition models

- Essential fitment if taking your bike onto a track event

- Note: on many Norton SOHC engines (particularly pre-War), there were two sump plugs fitted - one on the Timing side crankcase, at the side of the sump, and another in the 6pm position of the Drive side crankcase.  This plug type will fit both sides - but we also offer an 'improved' lipped type (below), for the Drive Side, which gives better seating for a fibre washer

1101_8

Norton Deep Head Type

-Lockwire

- Reduced Weight

1/4" BSP

- Norton Deeper head /shallower Curve (Pre-War) Engine Type

- Satin Nickel Plated Brass (some brass unplated may also be available)

- Drilled for Lockwire

- Centre bored and head shaped to reduce weight 

- Supplied with 1/4" BSP Dowty seal

- This sump plug starts off as the Deeper/Shallower Curved type - as seen on Pre-War engines, however for these - as well as drilling them for lockwire, we also bore the centre, and shape the head profile to reduce weight

- Although rarely seen on production bikes out of the factory, it was a normal thing for the serious 'Tuners' to do on a competition bike - as they are noticeably lighter than standard

- I will also be the first to admit - they look very pretty and are a 'focal point' on any competition bike - for that extra bit of Bullshit!

1101_9

Norton Curve Head

-Improved 'Lipped' Design

1/4" BSP

- Curved Type Norton Head

- CNC machined from Brass bar

- Satin Nickel Plated Brass (some brass unplated may also be available)

- Improved 'Lipped' design, with milled Hex - improved seating of washer

- Slotted for screwdriver and drilled for lockwire

- Supplied with 2 x 1/4" BSP Copper washers

We have manufactured this sump plug to our own 'improved' design - in that these are CNC machined from 0.750" round Brass bar, and then the Norton Hex head is milled as a seperate operation. 

- This broader lip provides a much better seat, when using red fibre washers, to give better sealing

- We manufactured this lipped sump plug specifically for the drive side of SOHC engines that have the 6pm drain plug, with a wide milled face - ideal for this lipped nut (see photograph)

- I have also seen a similar lipped brass sump plug fitted to an original Pre-War Manx upright gearbox - but cannot guarantee it came from the factory with that plug fitted - although it looked nicely tarnished!

- Supplied with copper washers - but red fibre can also be used as lip gives ideal seal

- More expensive than other plugs - as additional milling required and more expensive material used

1101_10

Norton Curve Head

-Improved 'Lipped' Design

- Reduced Weight Racing Type

1/4" BSP

- Curved Type Norton Head

- CNC machined from Brass bar

- Satin Nickel Plated Brass (some brass unplated may also be available)

- Improved 'Lipped' design, with milled Hex - improved seating of washer

- Supplied with 2 x 1/4" BSP Copper washers

As above, this is our own improved 'Lipped' design sump plug - providing a wider face for improved sealing with red fibre washers

- This version also has our centre bored 'reduced weight' head design - so looks particularly pretty, as well as being lighter than the version above

- it is also drilled for lockwire, ideal for racing engines - particularly the drive side SOHC 6pm position hole, or racing gearbox's

- Supplied with copper washers - but red fibre can also be used as lip gives ideal seal

- The most expensive of our sump plugs, as a lot of machining time to manufacture

1101_11

Post 48 Type Sump Plug

- All Models, original design

-Stainless Steel

1/8" BSP

As fitted to most Norton models 1948 onwards

- Fitted to 1948 onwards engines, where sump plug is at bottom of crankcases sump 

- This type copies original design exactly, other than CNC manufactured in stainless steel

- Supplied with 1/8" BSP Dowty seal

It seems that Norton changed the design of the engine sump plug in 1948 - that being to a smaller diameter 1/8" BSP thread, which had a much finer thread than the previous 1/4" BSP plug.  I am told by other knowledgable Norton people this continued to 1961.

- I presume the reason for moving to this finer thread was because the position of sump plugs was also moved to the base (i.e. underneath) the sump of most engines - where there was not much metal in that casting.  (most OHV engines 48 onwards have a ramp under the sump of the engine surrounding the sump plug - to avoid the sump plug being pulled out, if 'grounding' the bike)

This plug copies the original Norton design sump plug exactly, including lips, other than being CNC manufactured in stainless steel.

Please ensure your engine still has the 1/8" BSP thread fitted before purchase (see also 1101_13 below)

1101_12

Post 1948 Sump Plug Design

- This type deeper head and drilled for Lockwire

1/8" BSP

This is the Post 1948 type 1/8" BSP sump plug

- This type has a slightly deeper head than standard, to allow it to be drilled for Lockwire

- Stainless Steel

- Supplied with 1/8" BSP Dowty seal

This Sump plug is similar to 1101_11 above, however we have deepened the head slightly to allow it to be drilled for Lockwire

- As would have been fitted to Post 1948 SOHC models for competition use (but also useful for any Post 48 models, and required if using your bike at any track event

-We have been careful to ensure the depth of the head on this type still does not protrude further than the cast ramp on the crankcase (on OHV crankcases tested - see photo)

1101_13

Post 1948 Sump Plug Design

- Larger diameter thread

7/16" BSF 

- Same dimensions as 1101_11, other than thread - which is a larger diameter 7/16" (0.436") x 18tpi BSF thread

- Stainless Steel

- Supplied with Copper sealing washer

- I am told that engine sump plugs were standardised with 1/8" BSP thread on all models from 1948.

- From 1948, the location of sump plugs (on all models I believe) was moved to the base of the crankcase sump, and a small ramp cast into crankcase, to ensure the sump plug would not be ripped out, if grounding the engine

- However, this thread/diameter does seem to have had a reputation for more easily stripping than the earlier 1/4" BSP plugs, previously fitted. 

- I have two original mid 1950's OHV/SV Norton crankcases in my possession, which I am confident have not been touched since the 1960's.  On careful examination - both sump plug threads fitted to these crankcases are tapped to take 7/16" x 18tpi BSF sump plugs.  Although both threads look original and good condition (see photo for this listing) - which means it may be an original, if unusual, thread . . . it is more likely this was a common 'replacement' thread, fitted in the 1950's/60's, if original thread stripped

Therefore - I have made a small batch of brass sump plugs - which are a hybrid of the original design, but with larger 7/16" x 18 BSF thread fitted. 

Also a suitable replacement - if your original 1/8" BSP thread has stripped . . . but satisfy yourself this thread is correct for your needs and you are able to tap crankcase to this size

1101_14 1/4" BSP Dowty Seal (Each) 1/4" BSP Modern type nitrile inner seal 'Dowty' Washer

- As supplied with each 1/4" BSP sump plug - these are a more modern sealing design and easier to fit than red fibre washers

- This is for a single Dowty washer, which ideally should be replaced when plug removed

- Note we also sell correct type Red Fibre washers if you prefer - Item 0092, but remember, they nee to be a tight fit when fitting onto the thread, to ensure they do not wobble at the final groove position

1101_15 1/8" BSP Dowty Seal (Each) 1/8" BSP Modern type nitrile inner seal 'Dowty' Washer

As above, but this is the smaller BSP size to fit the 1948 - 61 original type sump plug

We also sell copper alternatives - see below

1101_16 1/4" BSP Copper Sealing Washers (Pair) 1/4" BSP

- Soft copper sealing washers

- 1/4" BSP

- Sold as a pair

If you prefer a more traditional seal (other than red fibre) - we also offer these copper sealing washers, as a pair

- they are 0.75mm thick, slightly thinner than most fibre washers - so can be fitted singularly, or as I prefer - as a pair, to give more 'sponge'

1101_17 1/8"BSP Copper Sealing Washers (Pair) 1/8" BSP

- Soft copper sealing washers

- 1/8" BSP

- Sold as a pair

- As above, but for hte 1948/61 original type plugs, an alternative to Dowty or red fibre washers

- Sold as a pair

 

Background and Fitting Notes:

These are CNC manufactured by ourselves, but using original Norton sump plugs as a pattern - which we have copied exactly - including chamfers, grooves (most of these sump plugs have a specific type of groove behind the thread, which I assume was to let the red fibre washer to 'mush out' slightly and give more effective sealing) - and of course, the correct Norton head profiles.  We also linish (with fibre linishers) the head after manufacture to remove burrs, and then finally, every nut is ran down a thread gauge, to ensure the thread is deburred.  We have also manufactured additional varieties with cross-drilled holes for lockwiring - for track and competition use, and also some 'lightened' types with a very pretty drilled head.

Norton sump plugs for Norton singles were manufactured in their 1000's over a 50 year period - and as always there were slight variations and tolerances by batch - but we have compared multiple sump plugs and have tried to adopt 'std' tolerances wherever possible.  However, when fitting, try and ensure the thread fitting you have selected is correct for your model - always grease the thread first, and if not sure - play safe and confirm thread in casing first.

Note - Each of the sump plugs (between 1101_1 and 1101_12) comes supplied with a BSP Dowty sealing washer.  These are much easier to fit than the traditional Red Fibre Washer (which must be a very tight fit onto Norton sump plugs - and are difficult to fit - if they go on easy, they will 'wobble' when they get to the grooved area that all these sump plugs have). 

Dowty sealing washers are a more modern design - consisting of a steel outer with sealing nitrile inner - and are used in most modern fittings for sealing plugs.

We also sell these 1/4" or 1/8" BSP washers seperately (1101_14 and 1101_15 respectively), as ideally they should be replaced every time an oil change is performed.

We can also supply the traditional Red Fibre washers (Item 0091) if youj wish to use the traditional style washer - particularly on the Lipped type washers - but note these are normally a bit more difficult to fit.

Final point - if you have a different type of sump plug to the type shown here, and think it is original (i.e. early 1920's etc) - then feel free to email us and we may consider manufacturing a batch

 

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