SOHC Cambox rubber pad set, cut/planed from hard wearing oil resistent rubber (Nitrile), to the same width and thickness as originals, using a special jig for this purpose. These are fitted both above and below the rocker arm central boss in all SOHC cambox’s.

Along with the cork side washers, it is these being worn that normally results in these cambox’s leaking badly.

We use an original pre-war 'New Old Stock' Norton cambox rubber as the pattern to re-create these (bought many years ago from that great Norton exponent Phil Heath) to ensure the correct width.  Although they look very simple, they are not particularly easy to make . . . we buy slabs of the special oil resistent Nitrile rubber, cut them to approximate size blanks - but then have a special hardened jig (photos attached) to linish mill them to the correct dimensions (remembering that they may need further trimming to fit your own cambox).

Four rubbers are supplied, two for each rocker arm - one fits above (and is non adjustable) and the other fits below, and has some adjustment for wear - as it has a steel pad underneath it and an adjuster (both of which are manufactured by us in our Cambox section).  It would be nice if the top rubber had also been designed to be adjustable - but this would probably have meant the adjusters would foul the top tube of the frame.

The rubbers are slightly longer than required, which can be carefully trimmed to your required depth. They should be trimmed so they protrude just proud of the cambox slot, so the rocker arm has to be forced – carefully, into the cambox, as the originals were.  Take care not split or nick the rubber as you are pushing the rocker arms in place. The smooth end should be abutting the rocker boss and your trimmed end opposite.

Cambox Oil Tightness - Assembly Notes:

It is worth noting, it is never particularly easy to fit rockers after new rubbers and corks have been fitted - it is easy to think you are having to overly force everything together.  However, if everything is not a tight fit on first assembly - the cambox will quickly start to leak again once the engine has been ran a few miles. 

Therefore try and trim and assemble the rubbers so as much pressure as possible is being applied by the rubbers to the rocker surfaces.  As an indication - once the cambox is first assembled, the rocker arms should be very difficult to move by hand, feeling almost 'locked' up. 

The rocker arms should initially feel very stiff when first assembled, but they will soon loosen up in operation - but being like this should help ensure the cambox staying oil tight as long as possible.  This also applies to the rocker arm side washers (0062/0062b/0062c) - try and fit washers thick enough that some effort is required to fully tighten cambox rear cover (without damaging threads of course).  These will also compress a few thou in use - we sell different thicknesses for this purpose.

Final point on SOHC Cambox's leaking oil - after a period of time the top and bottom rubbing surfaces of the rocker arm centre hub (i.e. the area where the nitrile rubbers press against) get worn and sometimes scratched through dirt getting caught.  As long as smooth and reasonably evenly worn, the rubbers should still work.  However if scoring marks get excessive, even fitting new rubbers will only provide limited improvement.  If this is the case with your rocker arms, it may be necessary to have the rubbing areas of the rocker arms lightly milled.

There are some specialist Norton engine restorers who will sometimes perform this task, Email us at sales@racingvincent.co.uk if you think want more information on this.

I was asked for more information recently on fitting these by a customer . . . as it is indeed a fiddly and time consuming operation to trim them to fit your own cambox . . . and each time you try and push the rocker arms in . . . it requires some effort (unless you have over trimmed them . .. in which case it is quite easy to assemble!!) - so took some pictures of one of my own (magnesium) cambox shells and then overwrote the general sequence of trimming.  I know it is not particularly easy to read my writing - but look closely, follow the arrows and hope this helps.  It is important to note that there is 3 'planes' of the rubber - the Width, the Depth and the Breadth.

These are the half circular hardened steel plates that are located beneath the lower cambox rubbers, and which the rubber adjuster screws (A11/817) push against to ensure the lower cambox rubber's are held tight against the rocker arms. There are two per cambox (if only fitted under the lower rubber seals, so the adjusters push against them), and are therefore sold as a pair.

It is worth noting that rubber pads are fitted above and below the central hub of the rocker arms, to retain oil (hopefully!) - and although it is essential to use these hardened pads against the lower rubbers (because of the adjusters pushing against them) - the cambox casting slot that holds the upper rubber seals also had a curved shape at its extremity that makes it suitable for another set of these pads.  I have stripped original cambox's down and found these same half moon hardened pads behind the rubbers seals on the top rubbers as well  - often, pushing them in helps push the top rubbers against the rockers.  I show this in the accompanyning photo.

As a further FYI - I have seen racing cambox's where these pads are fitted on the top slots as well - but the end of the hardened half moon pads have been tapered slightly (probably on a linisher) - the idea being:  fit the lower and top rubbers in the slots, but with the lower rubber adjusters slackened off, then carefully slide in the rocker arms, then feed in a hardened half moon pad into the cambox behind the top rubber and lightly tap it in (the tapered end assisting it being tapped in) - which helps push the top rubber against the rocker arm; then finally use the adjuster to push the lower rubber against the rocker arm.

I often get asked how tight the cambox rubbers should be - well many factors affect oiltightness of a cambox, but if the rubbers are correctly ajusted against the rocker arms, and new rocker cork washers are fitted - you should find on reassambly of the cambox - that the rocker arms are very stiff to move by hand - if they move easily, you probably have not got the rubbers tight enough against the rocker arms!  Hope this helps. 

Final Note:  The unuusual pattern on these pads is just colouration as a result of hardening and quite normal.

SOHC Cambox Rubber Pad Bottom Adjusting Screw (Stainless Steel) - Original Length Type.

This is the adjusting screw that is used to push the bottom rubbers up against the rocker arm centres. These need regular adjustment to prevent oil leaking from the cambox - Manufactured as per the original items, with square adjusting heads - Made in a high grade stainless steel, these are too pretty to sit under the cambox!

This is the original 'standard length' item (copied from an original pre-war item), but we also offer a slightly longer length item (0064L), which can be used if you wish to use less rubber but apply more pressure - if you have a worn rocker casting, more prone to leacking.

Price is Each (nuts sold seperately)

Overall length of this item: 39.5 mm (shaft length is 16.5mm)

We also supply the correct 'reduced head' nuts, as originally fitted, also made in stainless steel (Item No. 0064b).

If you would like to see how we make this bolt, follow the link to a Youtube video:

https://www.youtube.com/watch?v=PkFbMlyyCSE&t=197s

These are the special 'Reduced Hex' nuts, as originally fitted to the rubber pad (square) adjusting screw A11/817 - CNC manufactured in stainless steel to the original Norton pattern with Whitworth spanner size. 

Price is Each

Like so many other Norton engine fastenings - this nut was specially made for the Norton SOHC cambox adjusters - the hex being a smaller Imperial diameter (across flats) than would have been commercially available for that thread size.  In so doing, it allowed easier access to adjusting the square headed rubber adjusting screws, as a smaller spanner could be used.

We CNC manufacture these nuts to the original Norton dimensions - but in Stainless Steel, and we even mill the Hex (as it is now a difficult Imperial size to obtain commercially) - so although small and mostly hidden in use, they are very pretty to look at! (and this explains why more expensive than standard stainless nuts)

SOHC Cambox Rubber Pad Bottom Adjusting Screw (Stainless Steel) - Longer Length Type (approximate 1.8mm longer than standard length).

This is the adjusting screw that is used to push the bottom rubbers up against the rocker arm centres. These need regular adjustment to prevent oil leaking from the cambox - CNC Manufactured as per the original items, with milled square adjusting heads - Made in a high grade stainless steel, these are too pretty to sit under the cambox!

This is the 'longer length' type - where the shaft length at the front of the bolt is approximately 1.8-2mm longer than the standard version.  The reason for this - if you have a cambox where the central boss of the rocker arm has heavy scoring/scratches, it is likely to be more susceptable to leaking.  By using a slightly longer length you can use  less rubber but apply slighltly more pressure against the rubber.  Not really sure if this makes a difference - but I have put this under the heading 'every little helps'!.

Price is Each (nuts sold seperately)

Overall length of this item: 40.9 mm (shaft length is 18.3mm)

We also supply the correct 'reduced head' nuts, as originally fitted, also made in stainless steel (Item No. 0064b). 

If you would like to see how we make this bolt, follow the link to a Youtube video:

https://www.youtube.com/watch?v=PkFbMlyyCSE&t=197s

Oil Resistent Cork Washer, fits on either side of the rocker arm bearing - Fitting new cork washers helps keep the cambox oiltight - Cork thickness = These are 2.0mm (std) thickness.

Manufactured for RacingVincent by UK based specialist gasket manufacturer.

SOHC Norton Rocker Arms, side plates and cork washer information:  

For the duration that the Arthur Carroll SOHC engine was manufactured by Norton's (i.e. approx 1930 - 1957) there were at least 3 different rocker arm variations - possibly more.  The initial cambox rockers arms (I think approx 1930 - 33) had a smaller diameter central boss for the rocker arm.  The cork washers we sell here are a larger diameter than that earlier diameter - but it is easily possible to trim the cork with sharp scissors to fit the cambox shell recess.  The second type of rocker arm had the 'normal' larger diameter, which is the same diameter as these cork washers.  This second type of rocker arm used flat shims between the rocker/bearing sides and the cork.  We sell that (non lipped) flat shim - item 0288.  Not sure of exact periods for this type - but most pre-war cambox's I have seen have this flat shim (non lipped) type. 

The final rocker arm type I am aware of is the type that require a 'Lipped' side washer - Item 0287 in our catalog.  This type seems the most common. The rocker arm for this type is identifiable by each end of the central rocker arm boss having a lip machined around it, to fit the lipped washer.  The diameter of the cork washer for both non-lipped and lipped type rocker arms is the same.  Although I cannot be sure - I always assumed the 'lipped' type side washers were introduced because they put side pressure (of the cork) on the rocker arm boss itself, not the bronze bearing inside, as well as helping prevent leakage of oil from the central bearing/rollers.

Because restorers of these engines often end up acquiring mismatched rocker arms and cambox shells, we provide oil resistent cork side washers in three different widths.  In the past, I have found the side play of rocker arms to vary by cambox - and therefore a thicker cork washer on some being desirable.  A simple way of confirming this is to remove all traces of old cork washer, fit Blu-Tac or plasticine into the cork washer recesses of the cambox shell/rear cover, and then trial assemble the cambox with rockers.  Then strip and carefully remove rockers and use a depth gauge to carefully press into the soft plasticine to estimate the ideal thickness of washers required.  Dont forget to level out the differences between both sides, and allow a small additional amount for the cork compressing - it is this that stops the leaking!

Cambox Oil Tightness - Assembly Notes:

It is worth noting, it is never particularly easy to fit rockers after new rubbers and corks have been fitted - it is easy to think you are having to overly force everything together.  However, if everything is not a tight fit on first assembly - the cambox will quickly start to leak again once the engine has been ran a few miles.  Therefore try and trim and assemble the rubbers so it as much pressure as possible is being applied by the rubbers to the rocker surfaces.  As an indication - once the cambox is first assembled, the rocker arms should be very difficult to move by hand, feeling almost 'locked' up.  If the rocker arms are very still, they will soon loosen up in operation - but this should help ensure the cambox staying oil tight as long as possible.  This also applies to the rocker arm side washers (0062/0062b/0062c) - try and fit washers thick enough that some effort is required to fully tighten cambox rear cover (without damaging threads of course).  These will also compress a few thou in use - we sell different thicknesses for this purpose.

Final point on SOHC Cambox's leaking oil - after a period of time the top and bottom rubbing surfaces of the rocker arm centre hub (i.e. the area where the nitrile rubbers press against) get worn and sometimes scratched through dirt getting caught.  As long as smooth and reasonably evenly worn, the rubbers should still work.  However if scoring marks get excessive, even fitting new rubbers will only provide limited improvement.  If this is the case with your rocker arms, it may be necessary to have the rubbing areas of the rocker arms lightly milled. There are some specialist Norton engine restorers who will sometimes perform this task, Email us at sales@racingvincent.co.uk if you think want more information on this.

Update Autumn 2019:  New batch of cork washers just manufactured.  Apologies for price rise, but I am told that the price of cork has risen considerably since our last batch were made

Oil Resistent Cork Washer, fits on either side of the rocker arm bearing - Fitting new cork washers helps keep the cambox oiltight - Cork thickness = These are 2.4mm (med) thickness.

Manufactured for RacingVincent by UK based specialist gasket manufacturer.

SOHC Norton Rocker Arms, side plates and cork washer information:  

For the duration that the Arthur Carroll SOHC engine was manufactured by Norton's (i.e. approx 1930 - 1957) there were at least 3 different rocker arm variations - possibly more.  The initial cambox rockers arms (I think approx 1930 - 33) had a smaller diameter central boss for the rocker arm.  The cork washers we sell here are a larger diameter than that earlier diameter - but it is easily possible to trim the cork with sharp scissors to fit the cambox shell recess.  The second type of rocker arm had the 'normal' larger diameter, which is the same diameter as these cork washers.  This second type of rocker arm used flat shims between the rocker/bearing sides and the cork.  We sell that (non lipped) flat shim - item 0288.  Not sure of exact periods for this type - but most pre-war cambox's I have seen have this flat shim (non lipped) type. 

The final rocker arm type I am aware of is the type that require a 'Lipped' side washer - Item 0287 in our catalog.  This type seems the most common. The rocker arm for this type is identifiable by each end of the central rocker arm boss having a lip machined around it, to fit the lipped washer.  The diameter of the cork washer for both non-lipped and lipped type rocker arms is the same.  Although I cannot be sure - I always assumed the 'lipped' type side washers were introduced because they put side pressure (of the cork) on the rocker arm boss itself, not the bronze bearing inside, as well as helping prevent leakage of oil from the central bearing/rollers.

Because restorers of these engines often end up acquiring mismatched rocker arms and cambox shells, we provide oil resistent cork side washers in three different widths.  In the past, I have found the side play of rocker arms to vary by cambox - and therefore a thicker cork washer on some being desirable.  A simple way of confirming this is to remove all traces of old cork washer, fit Blu-Tac or plasticine into the cork washer recesses of the cambox shell/rear cover, and then trial assemble the cambox with rockers.  Then strip and carefully remove rockers and use a depth gauge to carefully press into the soft plasticine to estimate the ideal thickness of washers required.  Dont forget to level out the differences between both sides, and allow a small additional amount for the cork compressing - it is this that stops the leaking!  I normally keep a few of each type handy when assembling for this reason.

Cambox Oil Tightness - Assembly Notes:

It is worth noting, it is never particularly easy to fit rockers after new rubbers and corks have been fitted - it is easy to think you are having to overly force everything together.  However, if everything is not a tight fit on first assembly - the cambox will quickly start to leak again once the engine has been ran a few miles.  Therefore try and trim and assemble the rubbers so it as much pressure as possible is being applied by the rubbers to the rocker surfaces.  As an indication - once the cambox is first assembled, the rocker arms should be very difficult to move by hand, feeling almost 'locked' up.  If the rocker arms are very still, they will soon loosen up in operation - but this should help ensure the cambox staying oil tight as long as possible.  This also applies to the rocker arm side washers (0062/0062b/0062c) - try and fit washers thick enough that some effort is required to fully tighten cambox rear cover (without damaging threads of course).  These will also compress a few thou in use - we sell different thicknesses for this purpose.

Final point on SOHC Cambox's leaking oil - after a period of time the top and bottom rubbing surfaces of the rocker arm centre hub (i.e. the area where the nitrile rubbers press against) get worn and sometimes scratched through dirt getting caught.  As long as smooth and reasonably evenly worn, the rubbers should still work.  However if scoring marks get excessive, even fitting new rubbers will only provide limited improvement.  If this is the case with your rocker arms, it may be necessary to have the rubbing areas of the rocker arms lightly milled. There are some specialist Norton engine restorers who will sometimes perform this task, Email us at sales@racingvincent.co.uk if you think want more information on this.

Update Autumn 2019:  New batch of cork washers just manufactured.  Apologies for price rise, but I am told that the price of cork has risen considerably since our last batch were made

Oil Resistent Cork Washer, fits on either side of the rocker arm bearing - Fitting new cork washers helps keep the cambox oiltight - Cork thickness = These are 3.0mm (thick) thickness.

Manufactured for RacingVincent by UK based specialist gasket manufacturer.

SOHC Norton Rocker Arms, side plates and cork washer information:  

For the duration that the Arthur Carroll SOHC engine was manufactured by Norton's (i.e. approx 1930 - 1957) there were at least 3 different rocker arm variations - possibly more.  The initial cambox rockers arms (I think approx 1930 - 33) had a smaller diameter central boss for the rocker arm.  The cork washers we sell here are a larger diameter than that earlier diameter - but it is easily possible to trim the cork with sharp scissors to fit the cambox shell recess.  The second type of rocker arm had the 'normal' larger diameter, which is the same diameter as these cork washers.  This second type of rocker arm used flat shims between the rocker/bearing sides and the cork.  We sell that (non lipped) flat shim - item 0288.  Not sure of exact periods for this type - but most pre-war cambox's I have seen have this flat shim (non lipped) type. 

The final rocker arm type I am aware of is the type that require a 'Lipped' side washer - Item 0287 in our catalog.  This type seems the most common. The rocker arm for this type is identifiable by each end of the central rocker arm boss having a lip machined around it, to fit the lipped washer.  The diameter of the cork washer for both non-lipped and lipped type rocker arms is the same.  Although I cannot be sure - I always assumed the 'lipped' type side washers were introduced because they put side pressure (of the cork) on the rocker arm boss itself, not the bronze bearing inside, as well as helping prevent leakage of oil from the central bearing/rollers.

Because restorers of these engines often end up acquiring mismatched rocker arms and cambox shells, we provide oil resistent cork side washers in three different widths.  In the past, I have found the side play of rocker arms to vary by cambox - and therefore a thicker cork washer on some being desirable.  A simple way of confirming this is to remove all traces of old cork washer, fit Blu-Tac or plasticine into the cork washer recesses of the cambox shell/rear cover, and then trial assemble the cambox with rockers.  Then strip and carefully remove rockers and use a depth gauge to carefully press into the soft plasticine to estimate the ideal thickness of washers required.  Dont forget to level out the differences between both sides, and allow a small additional amount for the cork compressing - it is this that stops the leaking!  I normally keep a few of each type handy when assembling for this reason.

Cambox Oil Tightness - Assembly Notes:

It is worth noting, it is never particularly easy to fit rockers after new rubbers and corks have been fitted - it is easy to think you are having to overly force everything together.  However, if everything is not a tight fit on first assembly - the cambox will quickly start to leak again once the engine has been ran a few miles.  Therefore try and trim and assemble the rubbers so it as much pressure as possible is being applied by the rubbers to the rocker surfaces.  As an indication - once the cambox is first assembled, the rocker arms should be very difficult to move by hand, feeling almost 'locked' up.  If the rocker arms are very still, they will soon loosen up in operation - but this should help ensure the cambox staying oil tight as long as possible.  This also applies to the rocker arm side washers (0062/0062b/0062c) - try and fit washers thick enough that some effort is required to fully tighten cambox rear cover (without damaging threads of course).  These will also compress a few thou in use - we sell different thicknesses for this purpose.

Final point on SOHC Cambox's leaking oil - after a period of time the top and bottom rubbing surfaces of the rocker arm centre hub (i.e. the area where the nitrile rubbers press against) get worn and sometimes scratched through dirt getting caught.  As long as smooth and reasonably evenly worn, the rubbers should still work.  However if scoring marks get excessive, even fitting new rubbers will only provide limited improvement.  If this is the case with your rocker arms, it may be necessary to have the rubbing areas of the rocker arms lightly milled. There are some specialist Norton engine restorers who will sometimes perform this task, Email us at sales@racingvincent.co.uk if you think want more information on this.

Update Autumn 2019:  New batch of cork washers just manufactured.  Apologies for price rise, but I am told that the price of cork has risen considerably since our last batch were made

This is the bronze plunger Quill used to feed oil to the camshaft lobes if using a (pre-Featherbed) central oil feed SOHC cambox, i.e. Racing Internationals, M30/M40 and SOHC Manx.  Normal (aluminium) SOHC CS1/International cambox's are identifiable by having a plain bevel cover - but the competition cambox (normally magnesium shell) was identifiable by having a front bevel cover which had provision for an oil feed - and used this quill to push against the central feed cambox. 

As well as the Quill, we also sell the quill spring, Quill holder, copper washer - and of course the central feed camshaft - all available in this SOHC cambox section

We manufacture this (racing type) cambox Quill in 2 lengths - the most common type is identical in length and profile to the SOHC BigEnd quill (but with a smaller oil feed hole!) - it it this type we will normally supply in this listing.  However, we have also found a slightly shorter variation - which is somewhere between the normal type and the Featherbed type quill in length (approximately 23mm in overall length).  If you are replacing an existing cambox quill and believe it is this length - then you can email me on paul.norman@racingvincent.co.uk when ordering. (Note - We also sell a shorter 3rd SOHC Featherbed Models type - see Item 0067 for this Featherbed Type).

Update Jan 2024:  We are currently out of stock of the longer cambox quill, but are having a new batch manufactured - email me for details if required paul.norman@racingvincent.co.uk

We CNC manufacture these quills to the original Norton pattern from the best quality Colisbro Nickel Silicon bronze (it has a more coppery look than regular phospher bronze, and Norton originally used a similar hard wearing material).

Note : These plungers are NOT interchangeable with the Bigend Feed Quill/Plunger (even though they look the same), as this plunger has a smaller feedhole! and fitting one into the BigEnd will damage the engine.  If you have a cambox using this quill type fitted, always take great care to ensure you keep this and the BigEnd quill seperated.  If you have a box of old quills and are not sure if you may have fitted a quill of the wrong type, email us on sales@racingvincent.co.uk email for information on hole size correct for Bigends.