Where do I buy a new camshaft that will last?

[KiwiGF]

I need a new 356 camshaft for my rebuild and had decided an SRM was the best bet given comments on this and other forums about soft cams etc

But SRM have no stock and no confirmed delivery time for the next batch and I've not found one of their stockists have them either

Several suppliers offer " nitrided cams" but I'm not sure that means they will last given they are unbranded (albeit so are many parts)

So can anyone recommend an alternative supplier of good 356 cams to SRM, that will last the distance?

[BSA_54A10]

Nitriding is a process similar to case hardening ( or more rather through hardening which is just a very deep case ).
It is usually done to things that get cyclic shock loadings like cranks where it makes them substantially tougher.
I strongly recommend every one gets their cranks nitrided whenever they are pulled out for whatever reason.

Then there is Carbo-nitriding which uses both carbon & nitrogen so it makes parts both tougher and harder.

If you still have your old cam, then get it hard faced by either flame spraying or plasma spraying.
Do not get it hard faced by welding with stellite as this oft creates more problems than it fixes.
Finally you can get it built up with soft steel, ground then hard chromed.

[KiwiGF]

I have a couple of very worn 334 cams and a fairly worn 357 cam but sadly no 356 cam to refurb. I suspect it would be cheaper to buy a new cam than refurb these anyway, the journal areas are worn on the 334's as well as the lobes

Out of interest does anyone know if a std A10 cam can reground to the correct profile and lift without being built up first? If so does it need hardening afterwards or is the OEM cam the same hardness all the way through?
And if so again, does anyone know how one can tell if a 334 cam is not so worn that a simple regrind will fix it?

[bsa-bill]

Out of interest does anyone know if a std A10 cam can reground to the correct profile and lift without being built up first?

Hi KiwiGF
as far as I understand, they can be re-profiled but sometimes instead of being built up they take metal off the bottom of the cam maintaining the same lift, whether this is good practise or not I leave for others with more experience to say

[KiwiGF]

Thanks for your replies I found some info on the net which has helped and thought I'd share it. The info is

1. one can measure the base circle of a cam (the min dimension) and the lobe (the maximum dimension) and then calculate the "lift" and see how worn the cam is from that

2. It's common practice to regrind cams by taking metal from the base circle

3. Most OEM cams are hard all the way through so do not need hardening after regrinding to recover full lift

Generally the base circles do not wear much at all it's just the tip of the lobes that wear, so if one knows the lift of a cam one can tell how worn it is, that's apart from obvious wear or scoring etc

I measured my cams (all 4 lobes) - results below- and what I thought was worn 334 cam (cam 1) might be OK after all (if I can get the bearing journal area built up) -  its base circle is 008 smaller than it should be but it looks as if thats because its been reground before or at least think so!

If anyone can tell what the standard lift is of a 334 or 356 cam that would be great!

Cam 1 (67-0334 lobes look ok)
Base.  Lobe.    Lift
0.942  1.212    0.270
0.942  1.204    0.262
0.942  1.204    0.262
0.943  1.213   0.270

Cam 2 (67-0334 lobes look worn)
0.951    1.218   0.267
0.951    1.205   0.254
0.951     1.208  0.257
0.951     1.216  0.265

Cam 3 (67-0357 lobes look worn)
0.951      1.278.  0.328
0.951      1.264.  0.336
0.951      1.273.  0.325
0.951      1.278.  0.329

[MG]

Hi Kiwi!

Info on different cams incl. lift/elevation curves can be found here
http://atlanticgreen.com/bsamain.htm

Ref the info you found on the internet:

1. Is correct

2. Not really. When regrinding a cam, material must be removed equally around the lobe and base circle. The ratio of base circle diameter to lobe height must stay unaltered to keep the original lift figure.
Only removing material from the base circle is a common way to increase valve lift! Doing so to compensate a worn (flattened) lobe is not good practice, as it means altering the cam characteristics and valve acceleration. If the lobe apex is not "spikey" enough, the follower can lift off due to its inertia at high revs and then impinge on the cam surface as the valve is closed again by its spring, resulting in valve bounce and premature wear on the cam and follower.

3. Cams are only surface-hardened (case or induction hardened, often nitrided additionally), a through-hardened cam would be brittle and break in use. Many OEM cams even only got the lobe apex and flanks hardened, the base circle stays soft as it doesn't see any load anyway (valve play). Whether a cam can be reground without re-hardening is dependent on initial hardening depth and the amount of material removed.

Draganfly used to offer reground (and re-hardened) cams on an exchange basis (like for like). I got a reground 356 from them 2 or 3 years ago, but the engineer had clearly overdone it, the base circle diameter was smaller than the bearing surface on the shaft, resulting in the cam followers hitting their dead stop before reaching down to the base circle!
I could however send it back for a full refund, allegedly t'was a faulty batch that shouldn't have been sold in the first place. I stll chose a new SRM cam instead, which is doing its job in the engine ever since. Based on that experience I can not recommend Draganfly's cam exchange service, others might have had better results though.

You must be aware that regrinding a cam will lower the followers (and pushrods) and thus have an influence on rocker geometry. Not a problem when only the minimum of material is removed, it will even compensate re-cut valve seats to a certain extent.

HTH, Markus

[KiwiGF]

Thanks Markus

I'm still not sure if the a10 cams can be reground successfully and without re hardening but maybe some one will know for sure, or if there is a limit 010 maximum before a cam must be built up before grinding

It seems that it's possible to make cams too hard and cause wear in followers which would be the only reason not to do have it done at the same time as re grinding I suppose. I've also seen it said that followers and cams should both be hardened using the same process to avoid excessive wear problems

yes one cannot just grind the base circle at the least the lobes should be cleaned up to remove scores etc
A reground cam with smaller base circle dia will always have a different profile to the original (smaller all over) albeit it could be very similar and have the same lift

The reason I'm interested in experiences of this sort if work is that I could ask a local engineering shop to to the work on the cam but I suspect if was not successful then it would of course be down to me for asking for the wrong thing to be done! They won't have done many A10 cams....

As for ratio i guess if 010 is taken off the base then the same should be taken off the lobe (original height) to keep the lift standard

The atlanticgreen site graph shows the 334 cam as having about .1" more lift then my cam - maybe it's the lift of the valves not the cam itself On the graph- do you by any chance have an old cam you can measure to see if that info on lift on the site is correct?

[MG]

Sorry, no 334 cams left to measure, I had two but sold them both a while ago.
For the 356 and 367 chart he states cam lift rather than valve lift. No such info for the 334 though, but I'm sure someone has one kicking about.

Basically the cam lobes are simply scaled down in overall size during the regrind, so if say 1mm is removed from the base circle diameter, 1mm has to be removed from the overall lobe height, then the difference of the two figures (=lift) stays the same.

Btw, since you are looking for one: It would be easy enough to grind a 356 from your worn 357 cam, there's more meat around the lobes as the 357 has more lift and spreading, so you could end up with a 356 of almost original dimensions.
The correct way of doing it, lacking any data for hardness level and depth, is to measure hardness on the original cam, then grind it down close to the final shape, measure again, and if necessary re-harden at this point. Re-hardening leads to an increase in volume in the material, so the cam has to be ground to final shape AFTERWARDS! If there is no considerable loss in hardness on the finished cam, nitiriding will give a hard surface layer and increased fatigue strength, without the need for final machining as there is no warpage or increase in volume involved. Best to have both done, the readily ground cam and the followers.

Cheers, Markus

[muskrat]

G'day KiwiGF,
                  I've been away (babysitting GK's), I have a few old 356 and 357 cams here. Will have a look thisarvo.
Cheers

[olev]

Gday Kiwi,
Bj's Bikes and Bits (Brisbane) have half a dozen new MCS 357 spitfire cams in stock.
They want $210 each.
They could be a bit lumpy??
cheers

[Brian]

British Only Austria have 356 cams but I have no idea of the quality. I bought a set of followers off them a couple of years ago and they were very good.

Might be worth e-mailing them and ask them who makes them etc.

http://www.vintage-motorcycle.com/index.php?language=en&site=4&pid=201&id=3911&suchtext=bsa camshaft&limit=0

[KiwiGF]

Hi Olev it's me Simon we met at the Gatton swap meet and I'm too old for the 357 cam in fact I thought long and hard about upgrading to the 356....I still may stick with the 334 if I can't be positive about the quality of a new 356 or find a used OEM one that can be reground

Muskrat that would be great if you can measure the cams you have

I'll send an email to BOA but they may not tell me who makes em
 several suppliers Like Draganfly and burtons list cams but there are reports of early failure and I'd rather not take the risk of splitting the cases once the bike is finally on the road

[trevinoz]

Never too old for a 357!

   Trev.

[chaterlea25]

Hi All,
I would be suspicious immedietly of MCS cams, these are the people who I believe put the scroll the wrong way on the 4 spring clutch adaptors, made the centre of the 6 spring adaptor 15 thou too small for the bearing race and buggered up the valve spring dimensions 

The last cam I got from SRM was made by "Compcams" in the USA  ????
This has been fine and is working with a set of rebuilt followers also done by SRM

All my 2 cent opinion
HTH
John O R

[olev]

Gday Simon,
Got back home ok, I see.
I bought a good 356 off Mike a couple of years back.
Have you still got his card? He's the bloke who gave you the drum on your clutch centre.
It would be interesting to see what a 357 does to a low compression A10.
Years ago we dropped a set of SH (Shit Hot??) cams into a standard 500cc Matchy.
It was a very nice motor.
cheers

PS: I haven't had much luck with MCS products either.