Author Topic: Push Rod 'Comb'.  (Read 1867 times)

Offline alanp

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Push Rod 'Comb'.
« on: 21.04. 2012 11:44 »
Have just completed a valve grind on the RGS rep (not my favourite job!) and naturally used the comb to position the push rods as I lowered the rocker box. However, while the comb is useful it's not perfect so I thought I would raise this topic to discuss the process.
1) I fitted the spark plugs into the head to avoid anything dropping inside during the struggle and found that the comb needed a notch in it to clear the plug. This worked out fine and you might want to modify your comb since I found that this also helped to keep the comb in position in one direction...up to a point...
2) I find that the weight of the push rods, the SRM steel ones, push the comb, and hence the rods, forwards out of position so I had to hold the comb in position with one hand while struggling to lower the rocker box assembly such that the push rod ends located in the rocker cups. Does anyone have any ideas on how to keep the comb in the correct position without holding it while getting the rocker box assembly down without nudging it out of position? I was thinking about how much easier it would be if the comb stayed put.
Cheers
Alan
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Offline bsa-bill

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Re: Push Rod 'Comb'.
« Reply #1 on: 21.04. 2012 12:45 »
Hi alan
Good tip about using the plug to keep the comp in situ, I'll try that next time.
I generally use the comb to keep the push rods in place until the rocker box is down on the head, then I poke an index finger into the box from front or back and feel for the rocker cup and push rod, I then jiggle the appropriate rocker up and done (with the tappet slackened right back) while guiding the push rod with the end of the finger until it clicks into the rocker cup.
This sounds a bit fiddly but it,s not really. Usually some of the rods engage correctly anyway.

most important don't forget to remove the comb DAMHIK *doh* *doh* *doh*
All the best - Bill
1961 Flash - stock, reliable, steady, fantastic for shopping
1959 Rocket Gold Flash - blinged and tarted up  would have seizure if taken to  Tesco

Offline TT John

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Re: Push Rod 'Comb'.
« Reply #2 on: 21.04. 2012 13:24 »
Hi Alan. I found that if you get all the push rods more or less level, can't remember what position, then put plenty of thick grease on the surface of the comb, thats if your using grease as a sealer on the gasket, elastic bands on the rocker arms acros the top of the cover to hold them in position, then after a couple or three attempts, you just might get them in place without too much stress. ;)
Thats my 2ps worth nope this helps. 


TTJohn

Offline LJ.

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Re: Push Rod 'Comb'.
« Reply #3 on: 21.04. 2012 13:50 »
I've found it easier to discard the comb and completely slacken off the tappet screws... then while carefully placing the rocker box slowly onto cylinder head... and with a small torch, you can just about see the rocker cups inside, sometimes they stay up if the spindle spring are good. It is then a case of uniformly tightening up all round, keeping a careful check that push rods have not slipped out of the cups.
Ride Safely Lads! LJ.
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1947 BSA M21 600cc Girder/Rigid-Green
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Online chaterlea25

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Re: Push Rod 'Comb'.
« Reply #4 on: 21.04. 2012 15:30 »
Hi All
AS LJ suggests, small torch a piece of stiff wire bent into a hook  *idea*
I found the comb gets stuck to the gasket or the rocker box making a mess of the Hylomar *sad2*
HTH
John O R
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Offline Goldy

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Re: Push Rod 'Comb'.
« Reply #5 on: 21.04. 2012 16:33 »
Yes agree with that I have never used a comb, just a good torch and dentist mirror.
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Offline cotterpinkid

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Re: Push Rod 'Comb'.
« Reply #6 on: 21.04. 2012 19:57 »
For sale - Pushrod Comb - used once and never again.

I found it a hinderence. As with others just slacken the tappets off and feed the the pushrods into the cups as the rocker box is lowered.
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Offline 0116harley

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Re: Push Rod 'Comb'.
« Reply #7 on: 25.04. 2012 12:16 »
For sale - Pushrod Comb - used once and never again.

I found it a hinderence. As with others just slacken the tappets off and feed the the pushrods into the cups as the rocker box is lowered.
     Hi all, i also found it  a pain trying  to hold one of these combs with one hand and putting the rocker cover on with the other. Anyway i just bent the comb to suit and welded a bracket on. Then drilled a hole so it fits over the spark plug, then just tighten it up with a nut.  makes the job easy being able to use both hands
cheers neil

Offline alanp

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Re: Push Rod 'Comb'.
« Reply #8 on: 25.04. 2012 16:52 »
Thanks Neil - the next time I have to do that rocker box lowering job (I wish never but I know it will happen) I'll make that mod to the comb.
I've tried not using the comb but it drives me crackers trying to peer inside and get the push rods in their cups.
I bet it's easy if the engine is on the bench.
Alan
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Online Topdad

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Re: Push Rod 'Comb'.
« Reply #9 on: 26.04. 2012 10:29 »
Good morning Alan, I agree this is the one job I hate doing due to fact that it's fiddly and that at the end you'll probably end up with an oil leak as well as acheing wrists . The only way I've acheived an easy and oiltight outcome was when a mate of mine who had extremly long and dextreous fingers used to help me ,he could click 'em in place in a wink and most times as I say  it was oiltight. I wonder why they didn't go with a huntmaster type rockerbox which had I seem to remember an opening on it's top to do this awkward  job? best of luck BobH
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Offline alanp

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Re: Push Rod 'Comb'.
« Reply #10 on: 26.04. 2012 11:31 »
Good morning Alan, I agree this is the one job I hate doing due to fact that it's fiddly and that at the end you'll probably end up with an oil leak as well as acheing wrists . The only way I've acheived an easy and oiltight outcome was when a mate of mine who had extremly long and dextreous fingers used to help me ,he could click 'em in place in a wink and most times as I say  it was oiltight. I wonder why they didn't go with a huntmaster type rockerbox which had I seem to remember an opening on it's top to do this awkward  job? best of luck BobH
I'm not familiar with the Huntmaster rocker box but looking at the A10 it seems that once they had decided to put the engine steady brackets right at the top and centre of the engine they were a bit stuck for options to increase access as well as giving it sufficient rigidity. I expect the engines were assembled on the bench prior to installing them into the frames on the BSA production line giving good viewing inside the rocker box so it didn't seem important.
The rearmost rocker access cover has one fixing nut which is just about inaccessible if you tighten up and mount the engine steady brackets before putting on the rearmost cover and also its top cover stud makes getting the rocker box under the top frame and into position to lower it onto the head another frustration. That engineer should hold his head in shame for inflicting this on us.
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Offline muskrat

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Re: Push Rod 'Comb'.
« Reply #11 on: 26.04. 2012 13:57 »
And they put flats on that nut's stud. So you could take it out before lifting the box or put it in after the box is fitted. *idea*
Cheers
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Offline 0116harley

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Re: Push Rod 'Comb'.
« Reply #12 on: 26.04. 2012 15:01 »
Thanks Neil - the next time I have to do that rocker box lowering job (I wish never but I know it will happen) I'll make that mod to the comb.
I've tried not using the comb but it drives me crackers trying to peer inside and get the push rods in their cups.
I bet it's easy if the engine is on the bench.
Alan
Hi Alan its also one of them jobs that drives me crazy. luckly you dont have to do very often. Havin said that ive had to take the cover of twice this month. , ive cursed the bike a few times trying to get the pushrods in the cups. Good job the missis wasnt listening at the shed door as im saying things like "get in there please get in". Then a big sigh of relief as the rods fall into the cups. *doh*

Offline alanp

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Re: Push Rod 'Comb'.
« Reply #13 on: 26.04. 2012 15:40 »
And they put flats on that nut's stud. So you could take it out before lifting the box or put it in after the box is fitted. *idea*
Cheers
Didn't know about a flat on the stud unless you're pulling my leg (?).
If you take the stud out when the tappet cover is off to get at it to extract it you'd have to watch out you don't drop it into the push rod 'chasm'. Been there, dropped a hex key down there, couldn't get it out without taking the dreaded rocker box off again, aaaggh!

The next time (there's bound to be a next time!) it's apart I'm going to fix the stud to the nut so that it comes out with the nut or maybe replace the stud/nut with a suitable screw. With these ideas it will make life easier but I fear it won't turn a sow's ear into a silk purse, just make it accompanied by fewer swear words.
Cheers
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