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1961 CB72 Project

Want to keep a Restoration Log? Post it here! You can include photos. Suggested format: One Restoration per Thread; then keep adding your updates to the same thread...
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G-Man
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Post by G-Man » Sun Sep 13, 2015 2:30 pm

Finally got a bit of workshop time today and made a little progress. I put the valves in with new springs and carefully cleaned collets keepers and retainers.

The cams went in the freezer overnight so it was a pretty simple job to tap the bearings on to each shaft. That big sprocket makes assembling the cam in the head a little fiddly as it obscures the view of the splines more than the later type. The sprocket nut has a spring detent to stop it coming undone and that added to the general fiddliness of the operation, but eventually it all went together.

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I did a bit of a dry run with the points and tacho drive covers but the combination of this big nut and the tighter dimensions of the early tacho drive cause the two to foul and stop the cam from rotating.

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I could have taken the dremel to the casting but that seemed a little drastic. A quick search through the spares box turned up a smaller nut which fixed the problem.

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Before I put in the rocker shafts, I had to remnd myself which was the bigger of the two locations, so I just put a reamer in the holes and found out which was which.

After that the rockers and shafts slid nicely into place.

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It was then time to put in the gasket, knock pins, o-rings and M6 studs before lowering the head into place.

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The cam chain that I got from David Silver was a genuine DID endless version and I got some rivet links to go with it. First I had to take the chain apart with my new riveting tool. This came without instructions but I was able to download some for a very similar device. Once all the guides anvils and springs were in place, splitting the chain was easy.

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Getting the chain riveted back together in place was a little more tricky because of tight clearance and I struggled to get the tool centralised on each pin.

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Eventually I though I had it done but when I looked at this picture, I realised that I had overdone one of the pins and cracked it. The instructions warned of this but I succeeded in proving that it could happen!

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I think that's a job for my next workshop session. I'll remove that link and put a fresh one in with a little more care.

In any case, it's starting to look a little more like an engine....

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G
'60 C77 '60 C72 '62 C72 Dream '63 CL72
'61 CB72 '64 CB77 '65 CB160
'66 Matchless 350 '67 CL77
'67 S90 '77 CB400F

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Seadog
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Post by Seadog » Sun Sep 13, 2015 2:38 pm

Nice to see you back to it. It looks great. You've come a very long way.

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G-Man
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Post by G-Man » Sun Sep 13, 2015 3:28 pm

Thanks, Seadog! So far that I forgot to look for a screwdriver handle. Sorry!

G
'60 C77 '60 C72 '62 C72 Dream '63 CL72
'61 CB72 '64 CB77 '65 CB160
'66 Matchless 350 '67 CL77
'67 S90 '77 CB400F

Steverino
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Post by Steverino » Sun Sep 13, 2015 6:19 pm

As usual, beautiful work G-Man.
Why are you choosing to rivet your chain instead of throwing on a master link? The number of times I've had the heads off and on my CA95's and CB160s would make me insane having to rivet them. I mean no offence by asking this question, You are the teacher and I am the student I genuinely want to know the pluses and minuses. One of them I probably already know because I've thrown a few cam chains in my life. Also, is the CB72/77 and interference engine? My little twins aren't is why I've got away with master links my whole life. Thanks G-Man!
Steve

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G-Man
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Post by G-Man » Mon Sep 14, 2015 1:41 am

Steve

I don't have a 'real' reason other than the spring links sometimes have pins of different diameter from the chains you can get. Also I got this chain tool to dismantle the chains I could get and thought I would give it a try...... Might just replace his one with a spring link....

Pretty sure that these are 'interference' engines. Don't want to test that theory. It was enough sorting out my wife's Ford Fiesta when the cam belt broke......

Renold bicycle and motorbike chains were much easier. I Used to just do those with a hammer and punch. They had shouldered pins and proper rollers. Altogether a better design.

G
Last edited by G-Man on Thu Dec 28, 2017 2:20 am, edited 1 time in total.
'60 C77 '60 C72 '62 C72 Dream '63 CL72
'61 CB72 '64 CB77 '65 CB160
'66 Matchless 350 '67 CL77
'67 S90 '77 CB400F

honda brian
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Post by honda brian » Mon Sep 14, 2015 2:46 am

Nice one Graham. Have you thought of using an endless cam chain? I have bought three which are used as go cart race chains and am going to try one on my next build. As long as I remember that it's the first thing to go in, it should be OK. I'll be the first to know.
Keep up the good work. Brian.

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G-Man
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Post by G-Man » Mon Sep 14, 2015 5:03 am

Hi Brian

Yes - an endless chain makes sense, but like you say - it really needs to go in first thing and it certainly hadn't on this occasion.

Also - unlike the later engines with a detachable sprocket I think it could be quite a chore to get the chain hooked up with the timing correct and the cam in place

G
honda brian wrote:Nice one Graham. Have you thought of using an endless cam chain? I have bought three which are used as go cart race chains and am going to try one on my next build. As long as I remember that it's the first thing to go in, it should be OK. I'll be the first to know.
Keep up the good work. Brian.
'60 C77 '60 C72 '62 C72 Dream '63 CL72
'61 CB72 '64 CB77 '65 CB160
'66 Matchless 350 '67 CL77
'67 S90 '77 CB400F

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