The BSA A7-A10 Forum

Technical => A7 & A10 Engine => Topic started by: snowbeard on 13.05. 2009 07:26

Title: magnetized cam followers?
Post by: snowbeard on 13.05. 2009 07:26
so in all these bits, I have a few cam followers, and none of them seem to be magnetically attractive.

but in my spitfire, when I pull the push rods they seem almost suctioned into the cam followers?  I messed around a bit to see if they really felt that way, and they seem to be almost magnetic?   the first time I pulled them out, I thought they were seated into a rubber boot, it was so strong!

so I can guess that this isn't common practice, as magnetizing them would cause all the schralp to accumulate on them, but does anyone know of any trick like this? ever hear of such a thing? or feel what I described when removing them?

on another note, how does one extract the pin that keeps the middle two followers in place?  I have two pins out of barrels, and they seem to have two flats, a recessed line down one, and a groove around one end making it almost look like a bullet?

Title: Re: magnetized cam followers?
Post by: A10Boy on 13.05. 2009 15:39
I think its more likely to be a hydraulic thing with the oil.
Title: Re: magnetized cam followers?
Post by: shabashow on 13.05. 2009 18:27
There should be a grub screw in the middle of the back of the barrels just above the pin. When that's undone, a wee ball bearing should come out, the the pin will be free.
Title: Re: magnetized cam followers?
Post by: snowbeard on 13.05. 2009 19:08
aha, I'll have to look more closely for that screw.

you may be right A10boy, I did check the newer ones dry and clean...

I did get a comment from my favorite mechanic when he first heard the bike run that it was the quietest top end he'd ever heard. of course that was before I checked the tappet clearance, the person who worked on 'er long before me must have been a genius.  ;)

Title: Re: magnetized cam followers?
Post by: Daniel Toro (DT) on 07.06. 2009 22:05
Anybody have used this anti sump disposal?

Have some pictures, i can´t figure where install it.
Title: Re: magnetized cam followers?
Post by: MikeN on 08.06. 2009 10:46
If your cam folowers have become magnetized (or any internal engine parts)you need to get them de-magnetized before you use them. If you can find an engineering shop that does surface grinding they will be able to pass them over their de-magnetiser.
Title: Re: magnetized cam followers?
Post by: RichardL on 08.06. 2009 12:24

Any ferrous metal will be mildly magnetized when it is worked, as in hammering. However, I believe this would be very mild in the case of the cam followers and not likely to be enough to affect how it feels when you go to remove the pushrods, which are at the opposite end from where the magnetization would occur. I believe the  holding power of the cam followers for the pushrods is just nature abhoring a vacuum. The follower is formed to the diameter of the pushrod end and the oil makes an effective seal.

Richard L.