Box of bits assembly of 1955 G80S

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dave16mct
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Re: Box of bits assembly of 1955 G80S

Post by dave16mct »

Here's a coupe of pics of the dynamo clamp arrangement:
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Dave.
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dave16mct
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Re: Box of bits assembly of 1955 G80S

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RobC_LAPSED
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Re: Box of bits assembly of 1955 G80S

Post by RobC_LAPSED »

Thanks all for your expertise, photos etc. Much appreciated. It does lead me to some secondary questions though!

It looks like the head will be coming off then to sort that thread. Thanks for pointing out that other bolt, that is also wrong, I'll get another for that when I sort it. Good tip on cleaning out the bottom of the holes too. I see from the parts book that the bolts are 5/16 x 22tpi. Is this BSF thread, as I see that 5/16 BSF is 22tpi? (britishfasteners.com, a great source of info). I see its only 5deg difference on the tread profiles between BSC and BSF, not sure helicoils are that precise? Just so that I get the correct helicoils.

On the Dynamo fixings from the photos (thanks Dave), I guess what I see there is the square/hexagonal crossbar with bolt through it, into the threaded sleeve, in the eye of the strap? Is that the hinge pin at the bottom? I guess the metal strap just clamps the dynamo against the engine side of the plate holes then and the chain is adjusted by swivelling the dynamo?

Thanks, Rob
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dave16mct
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Re: Box of bits assembly of 1955 G80S

Post by dave16mct »

Hi Rob, be carefull with thread sizes. Only in 1/4" are BSCY and BSF similar. Get a chart such as Zeus which gives all the info including tapping drills. Probably find it on-line. Sounds like you're getting there. :D
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Re: Box of bits assembly of 1955 G80S

Post by Mick D »

Hi

It's a general rule of thumb that threads into aluminium on AMC machines are BSF - the rocker box fasteners are. Go for the correct thread insert confident it will match the replacement bolt ;)

Regards Mick
RobC_LAPSED
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Re: Box of bits assembly of 1955 G80S

Post by RobC_LAPSED »

Thanks for your thread inserts advise.
I've got the head off and sure enough it needs 3 or maybe 4 thread inserts for the rocker box bolts. Awaiting delivery of a tread insert kit.
While I got the head off I thought I'd have a better look at it. It does look like it's had a re-bore, new oversize piston, valve guides replaced and valves cleaned/ground in.
It didn't look to me like the inlet valve oil adjuster had been out for a very long time though, so thought it best to check it. Once the needle valve was out, it seemed there was little chance of any oil getting through that small hole into the oil way, let alone to the inlet valve. I took the valve out and sure enough it was well blocked up. I eventually got it cleaned out by poking a copper wire through the valve stem end and squirting lots of WD40 down there. At least it did show that the hole in the valve guide was in alignment! The exhaust hole had lots of gunge in there too so cleaned that out.

My question is, if this was rather neglected/overlooked, are there likely to be more potential pitfalls lurking in the engine bottom end! Are there lots of tiny oil ways that can get overlooked and left blocked up? Engine out and apart?
Rob
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Re: Box of bits assembly of 1955 G80S

Post by Greybeard »

After uncovering complete oil feed blockage on my thoroughly neglected '55 16MS project, I would certainly check the oilways to the big end bearing :shock:
http://www.jampot.com/forum/viewtopic.p ... 13#p229352

Steve
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Re: Box of bits assembly of 1955 G80S

Post by Mick D »

RobC wrote:Engine out and apart?
Ahh! That's the question as someone said before - whether to stop now with fingers crossed and risk the slings and arrows of outrageous expense etc.

It's an easy engine to work on and I'd strip it down for my own peace of mind. Don't worry about normal wear, these things are pretty agricultural and will generally plod on for many thousands of miles more, if all's clean and serviceable put it carefully back together. It'll cost you the price of a few gaskets and seals but what price peace of mind.

Regards Mick
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Re: Box of bits assembly of 1955 G80S

Post by RobC_LAPSED »

Thanks Guys. I knew the answer really! As you say, what price peace of mind.
After finding chewed up front wheel bearing nuts without it being taken apart/fixed (now apart), forks started to be dismantled and not finished (now been apart and reassembled) and those stripped head threads. I'm getting the impression that the previous owner/owners may have exhausted their engineering skill or resolve!
The engine will be the one thing I haven't fully taken apart (carb and a box of bits speedo the exception), so for peace of mind... If it then goes pop, only myself to blame!
Rob.
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Re: Box of bits assembly of 1955 G80S

Post by RobC_LAPSED »

Well that was worth checking!
The piston on the small end seems rather a tight fit, but even worse, god is that big end lumpy!! :(
What should the small end be made of? I'm familiar with white metal big end shells but this looks very like aluminium to me! It's got a crack and scours in it anyway so it will have to come out. Then I'll have to see what I can do with that crank!
Hey Ho, what fun!
Rob
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