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#889866 09/02/22 6:40 pm
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Mark Z Offline OP
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I wasn't sure whether to post this here or in the "What did you do to your bike today?" thread.

First I'd like to thank Alan and others for the advice about cracking each bolt and nut loose before re-torqueing - every bolt and nut turned more on tightening than it did on the loosening.

I didn't re-read, but I'm pretty sure my Chilton book says you only have to remove the exhaust rockers and pushrods to get at the center bolt. Not true, you have to remove the intake rockers and pushrods as well. Maybe if I made a tool to depress the valves, I could get the pushrods out without removing the rocker arms, but that's not happening today.
[Linked Image from i.postimg.cc]
But what BSA operation would be complete without some little glitch? This rocker end was stripped; the nut would not move in either direction. Since it's a "mushroom" type, the head would have to be cut off in order to remove it from the rocker arm.
[Linked Image from i.postimg.cc]
Fortunately, I have a spare intake rocker assembly that's been sitting on a shelf in my garage for around thirty years, so I was able to replace the rocker arm. Interestingly, this rocker arm appears to be steel instead of bronze like the other ones.
[Linked Image from i.postimg.cc]


Mark Z

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I am pretty sure all the rockers are forged steel. The bronze look is from the oil baking on them.
A spoon shaped tyre iron generally works to depress the springs enough to pull out the pushrod. Put it diagonally under the rocker and over the adjusting screw. Of course each tappet has to be sitting on the base circle of the cam.
The rockers are fairly hard, are you sure the rocker stripped and not the mushroom screw? Over tightening the adjuster nut could do that.

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If you think they are bronze ( which they aren't) put a magnet on them.


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To lift the pushrods out just use a 20mm spanner or similar on the
rocker arm from the pushrod side.
The rocker arms are forged steel, they may have been scrubbed with a brass brush.

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Mark Z Offline OP
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Originally Posted by DMadigan
I am pretty sure all the rockers are forged steel. The bronze look is from the oil baking on them.
A spoon shaped tyre iron generally works to depress the springs enough to pull out the pushrod. Put it diagonally under the rocker and over the adjusting screw. Of course each tappet has to be sitting on the base circle of the cam.
The rockers are fairly hard, are you sure the rocker stripped and not the mushroom screw? Over tightening the adjuster nut could do that.

Ok, yeah, the replacement rocker probably has way fewer miles on it (hence the color difference).

Next time around I'll try removing the pushrods without removing the rocker arms.

Yes, I believe the rocker END (not the rocker arm) and/or the locknut is stripped. The problem is, I can't remove the rocker end because the nut won't move (i.e., I would have to cut the "head" off the rocker end to remove it from the rocker arm). Substituting another rocker arm was the quicker solution.


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When components need to be hardened in one place and left soft in others, in this case only the bore of the rocker needs to be hard, copper plating is used.
The bore of the rocker would be masked with wax or similar then the rocker copper plated, then it would be case hardened. The copper resists the hardening process.


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Nice info folks. I have a little over 300 mikes on my restored spitfire. I should readjust the valves and retorque but its runnng so good I don't want to mess with it. The only problem so far was oil climbing the left rear head bolt. Cleaned it up and sealed it with some yamabond 4 . All is good.

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Mark Z Offline OP
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Originally Posted by Andy Higham
When components need to be hardened in one place and left soft in others, in this case only the bore of the rocker needs to be hard, copper plating is used.
The bore of the rocker would be masked with wax or similar then the rocker copper plated, then it would be case hardened. The copper resists the hardening process.

Andy, it sounds like you're saying that the difference in color of the replacement rocker arm is due to that arm's not being copper plated; is that right?


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Mark Z Offline OP
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Originally Posted by PFribley
Nice info folks. I have a little over 300 mikes on my restored spitfire. I should readjust the valves and retorque but its runnng so good I don't want to mess with it. The only problem so far was oil climbing the left rear head bolt. Cleaned it up and sealed it with some yamabond 4 . All is good.

I would advise biting the bullet and doing the retorque. I've neglected to do that on previous rebuilds, and I've had chronic oil seepage problems. If you see oil climbing a head stud, it is travelling across the head gasket, either from the pushrod tunnel or one of the oil drain holes, and will probably get worse.

Note the comments on removing the pushrods without removing the rocker arms; this makes the job a WHOLE lot easier.

OTOH, I see you're from Ohio, which means your riding days this year are numbered (unless you're one of those die-hards who ride all winter), so you may be able to put off the work till the end of the season.


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Originally Posted by Mark Z
Originally Posted by Andy Higham
When components need to be hardened in one place and left soft in others, in this case only the bore of the rocker needs to be hard, copper plating is used.
The bore of the rocker would be masked with wax or similar then the rocker copper plated, then it would be case hardened. The copper resists the hardening process.

Andy, it sounds like you're saying that the difference in color of the replacement rocker arm is due to that arm's not being copper plated; is that right?
Sometimes after hardening the copper plating is removed, it makes no difference if it is removed or left in place


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