• Welcome to the website of the Vincent H.R.D. Owners Club.

    Should you have any questions relating to the Vincent H.R.D. Owners Club, or Vincent H.R.D. motorcycles in general, please contact Graham Smith, Hon. Editor and Webmaster by calling 07977 001 025 or please CLICK HERE.

    You are unrecognised, and therefore, only have VERY restricted access to the many features of this website.

    If you have previously registered to use this forum, you should log in now. CLICK HERE.

    If you have never registered to use this website before, please CLICK HERE.

Series A single cam.


Andy B

Well Known and Active Website User
VOC Member
Gentlemen, being someone who is not afraid to ask the silly question can I have some thoughts on my cam for my 1937 Meteor. When lucky enough to purchase my A, it came with 3 engines, all singles, all in different condition and percentage of completion. Only one cam!! Can I have some advice on if anyone is making these, has made these in the past, if anyone has a spare they would swap or sell, if the cam that I have is salvageable? Pictures enclosed. Any thoughts would be welcome. I am presuming that the hex bolt on my cam is a later addition, was there a key before in its place, anyone have a picture of a good/original cam? Would this cam normally be just pushed off the gear? Thanks in advance. Regards Andy.
 

Attachments

davidd

Well Known and Active Website User
VOC Member
Andy,

I am not very good with the Series A parts, but I would try Neal Videan to see if he has cams and pinions. It would be worth getting some for any engine you currently have and he has been making them for twins.

I have seen A cams that do not push out, they were integral with the gear, but your cam certainly appears to be an assembly. I think most of the production A cams are two piece. The Allen looks like an addition to keep the cam from slipping inside the gear.

The cam pinion is E47B and the cam is usually marked with a "3X". I think the racing cam was a "4X".

David
 

Andy B

Well Known and Active Website User
VOC Member
Very much appreciate your feedback Dave, thank you and noted. I met Neal at a local swap recently so I will get in touch with him thanks, Andy.
 

A_HRD

Well Known and Active Website User
VOC Member
Andy,
In reply, perhaps the best thing I can do is quote from the Late Great Bob Stafford's "Ab Initio". It covers the cams, the pinion and the cam bushes - your early meteor bushes might be different to later ones (ie without the 3/16 dia peg??):

Three patterns of cam pinion were used, the standard plain gear, the lightened, recessed and polished
one on the specials and T.T.Rs. and the recessed and slotted type on the front camshaft of the Twins. The
interference fit of the shaft in the pinion is 0.001” to 0.0015” and theoretically any of the cams can be fitted
into any of the pinions and the same timing marks (if any) can be used. It should be mentioned that originally
no timing marks were used on the T.T.Rs, and where replacement gears have been fitted it is likely that they
too will be unmarked.

The camshaft bearings are merely iron or bronze rings, 1.126” OD with a 3⁄4” bore. Originally these
bearings were just trapped in a housing when the cambox cover was clamped down, later a 3⁄16” diameter
peg projecting 1⁄8” was fitted into the OD of the bearing, this peg being threaded either 2 BA or 3⁄16” BSF,
and it is to ensure that should the bearing ever come loose it will not rotate in the housing. Nevertheless,
if a seizure does occur the bearing does sometimes move and on rare occasions has been known to cause a
fair amount of damage. The inner bearings (ie. next to the barrel) are always iron as oil only reaches them
through a catchment on the cambox wall. The outer bearings can be iron or bronze as the oil supply to the
rockers runs by these bearings and some is diverted to the camshaft under pressure. It should be noted that
the outer bearing of the front camshaft of the Twins is always of bronze as this has also to withstand the
drive to the mag-dyno. The inner bearings have an oil hole in the top to line up with the catchment hole, the
outer bearings have a 1⁄8” wide 5 1⁄16” deep groove around the OD to pass oil to the rocker feed pipes and a
1⁄16” diameter hole drilled into the bearing to feed the camshaft.

The Series ‘A’ cams were known as 2X, 4X and 5X; timing figures approximate closely to Mk. I and Mk.
II post-war cams although the actual form is different, 2X were original equipment in Meteors, 4X in Comets
and 5X in Specials and T.T.Rs. Rapides were fitted with either 2X or 4X. The cam form is identical for all, that is the same shape on the rise and fall but the actual theoretical lift varies as follows: 2X — 0.320” lift inlet and
exhaust, 4X — 0.331 lift inlet and 0.333 lift exhaust, 5X — 0.333” lift inlet and exhaust: these differences in
lift are negligible but because of the variations in radii used on the various cams the valve timing is altered
appreciably, incidentally the radial relationship between inlet and exhaust cams is 172degrees (or 188degrees, depends which way round you go); on the Series ‘A’ models the cam nearest to the cylinder operates the exhaust valve.

Now to the theoretical timing of the cams which is as follows:

I.O. I.C. E.O. E.C.
2X: 40 BTDC 52 ABDC 65 BBDC 33 ATDC
4X: 44 BTDC 56 ABDC 68 BBDC 38 ATDC
5X: 48 BTDC 60 ABDC 71 BBDC 42 ATDC

Obviously it will be almost impossible to obtain these settings on worn components so my own method
is to use a degree plate and to set the inlet valve opening at its correct position then take a note of the actual
opening and closing points as they occur, the engine then has to be run to observe the performance.....

Peter B
 

A_HRD

Well Known and Active Website User
VOC Member
Andy,
In direct answer to your query I would say that your cam and pinion is usable at a push. The cam form looks reasonably OK. Cam and pinion were originally pressed together with 1 - 1.5 thou clearance. No key was used. If you have lathe access, it might be wise to put the round shaft in the chuck and check for run-out of the pinion; if it's all wonky you might be better sourcing another cam pinion assembly. Maughan's make the pinions. Presumably you have followers in reasonable condition?
Peter B
 

Dinny

Well Known and Active Website User
VOC Member
Hi Andy,

You are a few weeks too late as I have just assembled my bottom end. My cam is a one piece part which the early ones were. It was in good condition as were the followers so I reused them and when I timed the engine I got figures very close to the 5x cam.

If you want I can pull the cam box easily and take some pictures.

My rear cam bush was bronze and not iron, I hope that’s ok after reading Peters response.

Cheers
Mark
 

Shane998

Website User
VOC Member
Very much appreciate your feedback Dave, thank you and noted. I met Neal at a local swap recently so I will get in touch with him thanks, Andy.
Andy I was at Neals yesterday he's just back from holiday he does not have cams gets them from UK
 

Andy B

Well Known and Active Website User
VOC Member
Andy,
In reply, perhaps the best thing I can do is quote from the Late Great Bob Stafford's "Ab Initio". It covers the cams, the pinion and the cam bushes - your early meteor bushes might be different to later ones (ie without the 3/16 dia peg??):

Three patterns of cam pinion were used, the standard plain gear, the lightened, recessed and polished
one on the specials and T.T.Rs. and the recessed and slotted type on the front camshaft of the Twins. The
interference fit of the shaft in the pinion is 0.001” to 0.0015” and theoretically any of the cams can be fitted
into any of the pinions and the same timing marks (if any) can be used. It should be mentioned that originally
no timing marks were used on the T.T.Rs, and where replacement gears have been fitted it is likely that they
too will be unmarked.

The camshaft bearings are merely iron or bronze rings, 1.126” OD with a 3⁄4” bore. Originally these
bearings were just trapped in a housing when the cambox cover was clamped down, later a 3⁄16” diameter
peg projecting 1⁄8” was fitted into the OD of the bearing, this peg being threaded either 2 BA or 3⁄16” BSF,
and it is to ensure that should the bearing ever come loose it will not rotate in the housing. Nevertheless,
if a seizure does occur the bearing does sometimes move and on rare occasions has been known to cause a
fair amount of damage. The inner bearings (ie. next to the barrel) are always iron as oil only reaches them
through a catchment on the cambox wall. The outer bearings can be iron or bronze as the oil supply to the
rockers runs by these bearings and some is diverted to the camshaft under pressure. It should be noted that
the outer bearing of the front camshaft of the Twins is always of bronze as this has also to withstand the
drive to the mag-dyno. The inner bearings have an oil hole in the top to line up with the catchment hole, the
outer bearings have a 1⁄8” wide 5 1⁄16” deep groove around the OD to pass oil to the rocker feed pipes and a
1⁄16” diameter hole drilled into the bearing to feed the camshaft.

The Series ‘A’ cams were known as 2X, 4X and 5X; timing figures approximate closely to Mk. I and Mk.
II post-war cams although the actual form is different, 2X were original equipment in Meteors, 4X in Comets
and 5X in Specials and T.T.Rs. Rapides were fitted with either 2X or 4X. The cam form is identical for all, that is the same shape on the rise and fall but the actual theoretical lift varies as follows: 2X — 0.320” lift inlet and
exhaust, 4X — 0.331 lift inlet and 0.333 lift exhaust, 5X — 0.333” lift inlet and exhaust: these differences in
lift are negligible but because of the variations in radii used on the various cams the valve timing is altered
appreciably, incidentally the radial relationship between inlet and exhaust cams is 172degrees (or 188degrees, depends which way round you go); on the Series ‘A’ models the cam nearest to the cylinder operates the exhaust valve.

Now to the theoretical timing of the cams which is as follows:

I.O. I.C. E.O. E.C.
2X: 40 BTDC 52 ABDC 65 BBDC 33 ATDC
4X: 44 BTDC 56 ABDC 68 BBDC 38 ATDC
5X: 48 BTDC 60 ABDC 71 BBDC 42 ATDC

Obviously it will be almost impossible to obtain these settings on worn components so my own method
is to use a degree plate and to set the inlet valve opening at its correct position then take a note of the actual
opening and closing points as they occur, the engine then has to be run to observe the performance.....

Peter B
Thanks Peter for both those replies will be very useful when I eventually build the engine god willing!
 

Andy B

Well Known and Active Website User
VOC Member
Hi Andy,

You are a few weeks too late as I have just assembled my bottom end. My cam is a one piece part which the early ones were. It was in good condition as were the followers so I reused them and when I timed the engine I got figures very close to the 5x cam.

If you want I can pull the cam box easily and take some pictures.

My rear cam bush was bronze and not iron, I hope that’s ok after reading Peters response.

Cheers
Mark
No need for that Mark but thanks for the offer, hope it's all going to plan.
 

Top