850 MkIIa cams & tappers

Just removed the head & cylinders from my MKII, and I can see that both inlet cam lobes show the dreaded soft cam wear (but why only the inlet lobes?).
The tappets are also rather worn, possibly enough to make regrinding them not possible.

When I removed the head, one of thee 3 studs which should remain in the head stayed firmly in the barrel, resisting all my efforts to remove it. Possibly a DPO has used red locktit for some reason? I'll try applying some heat, but I'm not very optimistic. Two of the base studs also unscrewed - does anybody know the thread - whitworth or UNC? I'll have to try to find 2 suitable nuts to lock together to get the top nut off.

The head looks generally ok, a bit too much carbon though and one exhaust valves much lighter in colour than the other. Hmm.

It's always something of a voyage into the unknown, opening up a motor for the first time. I've a suspicion that one of the DPO's had an inventive turn of mind, so who knows what else lurks in there.

/Steve.

SteveBorland said:

Two of the base studs also unscrewed - does anybody know the thread - whitworth or UNC? I'll have to try to find 2 suitable nuts to lock together to get the top nut off.

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The lower end is UNC.

SteveBorland said:

Two of the base studs also unscrewed - does anybody know the thread - whitworth or UNC? I'll have to try to find 2 suitable nuts to lock together to get the top nut off.

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The base stud nuts are likely to be UNF - the linked circles show this - unless I misunderstand which ones you refer to.
Which would make the threads UNC. Not that Whit is much different for this for the 2 temporary nuts.

SteveBorland said:

The head looks generally ok, a bit too much carbon though and one exhaust valves much lighter in colour than the other. Hmm.

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The lighter one was burning less oil ?
Check how well the valve was seating though, if the seat was poor then it may have got hot from poor heat transfer.

Whilst somewould rather i not give people such FACTS YET AGAIN one possible reason for your premature cam and follower failure is that your crankcases are missing a design feature Mr Hopwood and others designed INTO the crankcases of the original Dominator engines in the late 1940s which somewhat less clever people later in charge knew sweet b****r all about and subsequent crank case patterns slowly removed it till eventually it no longer existed!! There is a word for such people..... I am refering to the camshaft oil bath which was DESIGNED to RETAIN as much oil as possible so as to CORRECTLY lubricate the cam and followers especially during the engine start up period, before oil gets thrown about in the cases, when galling can take place due to lack of correct lubrication and once galling takes place premature failure is assured. Your crankcases have the remains of this DESIGN FEATURE...its the big lump of useless alloy beneath the cam.
Is there anyone out there with a set of original model 7 etc cases they can photo and shov on this site to show this design feature for the benifit of others??
Of course there are many other reasons for premature cam failure......
One is that Norton at one time produced a batch of incorrectly hardened Commando cams, one is sitting in my freezing loft still with its Norton 'GENUINE SPARES' plastic wrappping...hardness is if memory is correct..... approx 350 Vickers whilst the hardness of the new 4S can on the book shelf behind me is approx 626 Vickers.
Another is because people DO NOT charge the crankshaft with oil before starting the motor after a rebuild along with not coating the cam and followers in assembly grease or some nice thick EP140 oil thus the cam and followers initially run dry resulting in galling taking place.
Yet another is where owners shove in a new cam but use old non reground followers once again resulting in galling taking place.
I guess yet another is reground followers not making full contact across the whole face of the new cam...... have never noticed this myself ..its not hard to shove the new cam in the cases, apply some emngineers blue to the cams, sit a barrel and followers on and then turn the cam over then take a look at the followers to see if full contact is being made. Finding the tube of engineers blue is, in my experience, the hard bit!! Its called OLDE AGE!!
But you will be happy to know that Andover Norton regularly manufacture batches of new followers... I assume because there is a big demand for them...funny that...I also assume new cams are reguarly manufactured as well!! This lack of design feature must keep a few people in fairly regular employment..... Of course at one time Triumph were replacing UNDER WARRANTY lots (25% I heard) of 650 exhaust cams due to lack of lubrication at the front of the motors, the inlet cams in the rear of the cases were OK as they received lots of oil being thrown off of the crank. Tis amazing what one hears from factory service people (metioning no names). Triumph (very quickly??) rather than including an oil bath into the cases (bodged it??) having later cams nitride hardened making the surface harder but dont drop one so the edge of a cam lobe strikes a hard lump of solid metal...bits of cam can flake off... as I once witnessed occur and heard lots of coulerful ancient anglo saxon words as the person responsible picked the cam up from the floor and noticed the damage....
No spell or grammer checks done.

J. M. Leadbeater said:

Whilst some would rather I not give people such FACTS YET AGAIN one possible reason for your premature cam and follower failure is that your crankcases are missing a design feature Mr Hopwood and others designed INTO the crankcases of the original Dominator engines in the late 1940s

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Well, you have raised this subject no less than eight times in the past eight months so I think that's probably enough about missing cam tunnels for a while, after all, no matter how many times this is mentioned, it doesn't change anything.

My MkIIA also suffered from chocolate cam syndrome - it seems that not all of them made it as far as the heat treatment plant. The bike had done 11k...
I'm not aware of this being an issue for earlier engines, but I'd happily stand to be corrected.
I never saw a Triumph cam wear out like this and they seem to manage OK without an oil bath?

Sorry to step in here, but I also have a 73 850, and have a question about the tappets: if there´s scratches on the surfaces that slide in the tunnels of the cylinder, i.e. the sides of the tappets, what do you do? As far as I have found, there´s no one selling tappets in oversizes? Or have I just not searched enough :?:
Tommy

fiatfan said:

Sorry to step in here, but I also have a 73 850, and have a question about the tappets: if there´s scratches on the surfaces that slide in the tunnels of the cylinder, i.e. the sides of the tappets, what do you do? As far as I have found, there´s no one selling tappets in oversizes? Or have I just not searched enough :?:
Tommy

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The latter... :mrgreen:

http://www.nortonmotors.de/ANIL/Norton Website/norton/price-list.php?criteria=tappet&Submit=Search

That said, I didn't check if they have them in stock...

Why would ANYONE who has had cam and lifter wear issues NOT convert to the BSA lifters and cam profiles during the rebuild? You already have it apart, why not do a more permanent fix?

Cost mostly. In my particular case, the landed cost of a set of Jim's cam, followers and pushrods will be around twice the price of a PW3 cam + new followers.
Then, having gone this far, you might as well put in a set of the beehive springs. Here in Denmark, we get charged 25% VAT on the cost of goods from outside the EU plus shipping and then a administration charge for making the VAT charge. It all gets a bit expensive.

It would be great to be able to choose the best solution irrespective of cost, but in the real world, some of us have a limited toy budget.

/Steve.

Danno said:

Why would ANYONE who has had cam and lifter wear issues NOT convert to the BSA lifters and cam profiles during the rebuild? You already have it apart, why not do a more permanent fix?

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For the last 35 years I did more than 100.000 mls with the same set of stock Norton lifters (once had them regrinded) and stock camshaft. Is that permanent enough for you :?: :!:

B+Bogus said:

fiatfan said:

Sorry to step in here, but I also have a 73 850, and have a question about the tappets: if there´s scratches on the surfaces that slide in the tunnels of the cylinder, i.e. the sides of the tappets, what do you do? As far as I have found, there´s no one selling tappets in oversizes? Or have I just not searched enough :?:
Tommy

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The latter... :mrgreen:

http://www.nortonmotors.de/ANIL/Norton Website/norton/price-list.php?criteria=tappet&Submit=Search

That said, I didn't check if they have them in stock...

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Aah man! I was on their site, but missed it . The downside is they are listed as "part not found", typically :evil: I guess I´ll send them an email, couldn´t hurt...
Tommy

fiatfan said:

B+Bogus said:

fiatfan said:

Sorry to step in here, but I also have a 73 850, and have a question about the tappets: if there´s scratches on the surfaces that slide in the tunnels of the cylinder, i.e. the sides of the tappets, what do you do? As far as I have found, there´s no one selling tappets in oversizes? Or have I just not searched enough :?:
Tommy

Click to expand...

The latter... :mrgreen:

http://www.nortonmotors.de/ANIL/Norton Website/norton/price-list.php?criteria=tappet&Submit=Search

That said, I didn't check if they have them in stock...

Click to expand...

Aah man! I was on their site, but missed it . The downside is they are listed as "part not found", typically :evil: I guess I´ll send them an email, couldn´t hurt...
Tommy

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In stock

Great, thanks, since I´m not sure how much wear there can be before you need to take action, I´ll put a pic up here for you to see. Feels like I need some expert advise on this.
Tommy