Cam followers

[redbloke1956]

Hi All, I have just removed my cam followers and inspected them, can anyone explain what Richardson means about cam follower wear?
I don't quite understand his explanation, my followers have some wear and am not sure if they are OK or not. I don't want to spend all the time setting up the timing and clearances if the followers are knackered.
Thanks in advance
Kevin

 

[timetraveller]

There are two places for the followers to wear ignoring the pivot tube which goes over the spindle. One is in the cup in which the push rod sits. Originally this was rare but with the bikes now 60 years old it is not unknown. Most frequent, and a fault almost from new, is the base of the follower. This should be flat, absolutely flat. Typically, before the days of stellited ones, the base would wear concave, very often with an unworn ridge left at one side where the follower had not been correctly lined up with the cam. If this wear is a few thou then it will not affect the running or performance. With the old case hardened followers and cams once you were through the case hardening then you were going to get very rapid wear of both the cam and the follower. It is unlikely that after all this time you will have the original followers unless the bike has been left unused for many years. If you have original followers and the depth of the concave wear is more than, say, 10 -20 thou it is time to get cams and followers stellited or replaced. The wear will cover about half of the length of the bottom of the follower and if it is slight it will be difficult to see without taking the followers out of the bike. If severe then it will be very obvious with just the light of a torch shining in on the side of the followers. The first type of wear mentioned, in the cups, used to be almost unknown, as the base of the followers always wore out first. However, with the advent of stelliting, the bases can now last so long that the cups can now be found severely worn. Good luck and if this is unclear then I can probably find a worn one to photograph.

 

[redbloke1956]

There are two places for the followers to wear ignoring the pivot tube which goes over the spindle. One is in the cup in which the push rod sits. Originally this was rare but with the bikes now 60 years old it is not unknown. Most frequent, and a fault almost from new, is the base of the follower. This should be flat, absolutely flat. Typically, before the days of stellited ones, the base would wear concave, very often with an unworn ridge left at one side where the follower had not been correctly lined up with the cam. If this wear is a few thou then it will not affect the running or performance. With the old case hardened followers and cams once you were through the case hardening then you were going to get very rapid wear of both the cam and the follower. It is unlikely that after all this time you will have the original followers unless the bike has been left unused for many years. If you have original followers and the depth of the concave wear is more than, say, 10 -20 thou it is time to get cams and followers stellited or replaced. The wear will cover about half of the length of the bottom of the follower and if it is slight it will be difficult to see without taking the followers out of the bike. If severe then it will be very obvious with just the light of a torch shining in on the side of the followers. The first type of wear mentioned, in the cups, used to be almost unknown, as the base of the followers always wore out first. However, with the advent of stelliting, the bases can now last so long that the cups can now be found severely worn. Good luck and if this is unclear then I can probably find a worn one to photograph.

Thanks so much Timetraveller, that is EXACTLY the sort of info I was looking for, my followers are quite badly worn then...I took a macro photo of the face and then blew it up on the computer (gotta love digital) and found that what I couldn't see with the naked eye was that the case hardening had obviously worn right through.
I tried to attach a photo to the post but it is just not happening for some reason, I can get 2 new followers locally from TPV so that is no problem but he doesn't have standard cams, can you tell me how much work is involved in fitting MK 3 cams...I have read somewhere about having to reove some metal from the bottom valve guide?
Is this difficult? do you know how much needs to be removed?
Thanks again for the info.
Regards
Kevin

 

[nkt267]

I have read somewhere about having to reove some metal from the bottom valve guide?
Is this difficult? do you know how much needs to be removed?

This only applies to Mk2's. You can fit Mk1 and Mk3 without modifying the valve guides as the lift is the same. Mk2 cams lift more and so the valve collar can hit the top of the lower valve guide. The correct way to modify valve guides for Mk2's is to remove 1/16th inch from the top of the guide and remake the taper on the top of the guide to allow oil to run off, but I am sure that there are a lot of people out there that have just filed (water tap reseating tool?)the top guide down and had no problems..John

 

[timetraveller]

Hi Redbloke. While you are having to mess around inside the timing chest to replace the followers it would be worth while checking the cams themselves. It is normal to find that the cams are also worn. If you looks at the top of the cam lobe and there are signs of scuffing or more normally a slight ridge to one side where the follower was not lined up properly then by looking at the height of that ridge you can see how much wear there is. Do not mix stellited and case hardened components. All case hardened, or more likely these days nitrided, or all stellited is the way to go. If there is no obvious sign of wear on the cam nose but you are still not sure then I can probably find a cam to measure up for both base circle and total eccentricity.

 

[redbloke1956]

cams?

Hi Redbloke. While you are having to mess around inside the timing chest to replace the followers it would be worth while checking the cams themselves. It is normal to find that the cams are also worn. If you looks at the top of the cam lobe and there are signs of scuffing or more normally a slight ridge to one side where the follower was not lined up properly then by looking at the height of that ridge you can see how much wear there is. Do not mix stellited and case hardened components. All case hardened, or more likely these days nitrided, or all stellited is the way to go. If there is no obvious sign of wear on the cam nose but you are still not sure then I can probably find a cam to measure up for both base circle and total eccentricity.

Thanks Timetraveller, The cam looks worn also as you guessed, however it doesn't have a ridge so maybe it was aligned correctly by accident, thanks for the offer of measurements but I think I will purchase new MK 3 cams. This bike is working out more expensive than my ex wife.

 

[nkt267]

This bike is working out more expensive than my ex wife.

Just don't tell her it is worth more;-)..john