Author Topic: Selectively stuck cam followers  (Read 371 times)

Offline Kit Carver

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Selectively stuck cam followers
« on: 23.09. 2019 21:13 »

Hi Gang - got a bit of a poser. I recently rebuilt the top end of my A10 engine - re-bore, new pistons, new valves/guides/springs and generally spruced her up. After running in for a while she started leaking around the head - not blowing, but oil seeping out from around pushrod tubes and oil ways - a perennial problem. Anyway, I stripped down to barrel, locktited the studs for good measure and put on a new head gasket and bolts, locktiting and torquing down. So far so good, BUT when I went to refit rocker box I noticed the push-rods on the left weren't moving with the engine. They're seating correctly, and were fine before I popped the head off. Can followers on one side only seem stuck, for want of a better diagnosis. Other side is fine. Any ideas, before I pull the whole thing down again? Anyone ever had this? After 37 years of A10 ownership this is a new one on me. Many Thanks, Steve.

Online Klaus

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Re: Selectively stuck cam followers
« Reply #1 on: 23.09. 2019 21:25 »
Hi Steve,
by turning the engine there is no move on the pushrods.....that means the cams on this side have no loobs *eek*

or this side the piston is in compression and both valves are shut.

Turn the enginie forwart and I am shure the pushrods will lift.


cheers Klaus


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Online bsa-bill

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Re: Selectively stuck cam followers
« Reply #2 on: 23.09. 2019 21:39 »
Quote
.that means the cams on this side have no loobs

or the camshaft is in two pieces = we hope not

All the best - Bill
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Online morris

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Re: Selectively stuck cam followers
« Reply #3 on: 23.09. 2019 21:53 »
Are they new followers?
Had an issue once with a new set where one or two followers where a bit hesitant to slide.
They where rather rough on the surface so I gave them a light polish in a lathe. Never had any problems with them after.
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Online KiwiGF

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Re: Selectively stuck cam followers
« Reply #4 on: 23.09. 2019 22:11 »

Hi Gang - got a bit of a poser. I recently rebuilt the top end of my A10 engine - re-bore, new pistons, new valves/guides/springs and generally spruced her up. After running in for a while she started leaking around the head - not blowing, but oil seeping out from around pushrod tubes and oil ways - a perennial problem. Anyway, I stripped down to barrel, locktited the studs for good measure and put on a new head gasket and bolts, locktiting and torquing down. So far so good, BUT when I went to refit rocker box I noticed the push-rods on the left weren't moving with the engine. They're seating correctly, and were fine before I popped the head off. Can followers on one side only seem stuck, for want of a better diagnosis. Other side is fine. Any ideas, before I pull the whole thing down again? Anyone ever had this? After 37 years of A10 ownership this is a new one on me. Many Thanks, Steve.

Is it as simple as pushing the rods down as you turn the engine? It’s only gravity that makes the followers contact the cam isn’t it? (Sorry for pointing out the “obvious”)
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Online berger

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Re: Selectively stuck cam followers
« Reply #5 on: 23.09. 2019 22:31 »
you have mistakenly locktited the two followers  *bash* *conf2*

Offline Gerry

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Re: Selectively stuck cam followers
« Reply #6 on: 24.09. 2019 00:22 »
Hi Steve with the rocker inspection covers off so you can see the valves and springs, are the left side valve springs compressed with no valve clearance and don't move when the engine is turned over. This would mean the followers are stuck and the spring pressure is not returning the valves to the closed position. If the valves are closed with no spring pressure then I suggest you re check the pushrod seating is correct in the followers and the rockers on this side. That would be the most likely cause of your problem. BEEN THERE DONE THAT!! Good luck Gerry

Offline bikerbob

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Re: Selectively stuck cam followers
« Reply #7 on: 24.09. 2019 08:46 »
Reading your post the way I understand it is you have fitted the barrel and the head and are attempting to fit the rocker box but because 2 cam followers are preventing you from doing so because they are stuck. The cam followers should be an easy sliding fit in the barrel if they are not then you could try giving them a gentle tap to see if they will free off but you will still be left with the problem of what has caused this to happen and if you went ahead and completed the rebuild what would happen if they stuck whilst the engine is running the  very least that would happen is you could end up with bent push rods. If I had that problem I would not hesitate and would remove the head and barrel and find out the cause of the sticking cam followers I would not be prepared to take the risk of going ahead without knowing what caused this problem.

Offline Swarfcut

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Re: Selectively stuck cam followers
« Reply #8 on: 24.09. 2019 08:59 »
Yes, I too would rather lift the barrel and have a look. If bergs is correct, a bit of heat from the good old hot air gun should be enough to soften the Loctite. They should be a nice free sliding fit in their bores.

Offline Kit Carver

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Re: Selectively stuck cam followers
« Reply #9 on: 24.09. 2019 09:57 »
Thanks everyone! Will have another go at all this after work today!

Offline Rocket Racer

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Re: Selectively stuck cam followers
« Reply #10 on: 07.10. 2019 01:48 »
I did come across a super rocket that had a refaced and sufficiently worn centre follower that was dropping low enough in the bores that it was getting caught and developed a sufficient burr to stick open. It got very rattly! the follower had to be tapped out. It sounded sufficiently sick the owner trailered it home part way through a club run.
A good rider periodically checks all nuts and bolts with a spanner to see that they are tight - Instruction Manual for BSA B series, p46, para 2.
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