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To Strip or Not to Strip?!
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whiteshadow



Joined: 24 Jan 2011
Posts: 78

PostPosted: Thu Aug 28, 2014 4:59 pm    Post subject: To Strip or Not to Strip?! Reply with quote

I've put back together my Singer 9 Engine (1933). But when clearing the garage it found 1 or possibly 2 aluminum end caps from the piston gudgeon pins.

These I remember were really loose and must have escaped in my fight to get the pistons in the block without snapping the rings. I'm not sure that all the pistons had them, but there were certainly a couple which were very loose. The pistons were fixed on the gudgeons..can't remember how and can't find the pictures.....so are the caps a fail safe?

.....What would you do??...strip down the whole engine again, with the risk of damaging hard to get parts or leave well alone? Rolling Eyes
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peter scott



Joined: 18 Dec 2007
Posts: 7113
Location: Edinburgh

PostPosted: Thu Aug 28, 2014 6:15 pm    Post subject: Reply with quote

If the gudgeon pins are not secured by circlips or a clamp bolt at the small end then I think you definitely need to protect the cylinder walls.

If getting the rings into the bores was difficult you may be able to lower the pistons to the point where the gudgeon pins are out the bottom without pulling the top rings out.

Clearly any skirt ring will still need to be refitted and it will be much easier if you remove the crankshaft.

If you don't have a complete set of caps then I would get some made.

Peter
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1939 SS Jaguar 2 1/2 litre saloon
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V8 Nutter



Joined: 27 Aug 2012
Posts: 587

PostPosted: Thu Aug 28, 2014 8:31 pm    Post subject: Reply with quote

If you don't fit the caps you will have serious problems. I remember reboring a six cylinder Continental engine, our customer rebuilt the engine himself. Continentals had nylon caps on the gudgeon pins. He thought they were just packing and threw them away. We had to fit six liners to cover the damage in the bores, he also had to buy six new pistons, because the pins were ruined.
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whiteshadow



Joined: 24 Jan 2011
Posts: 78

PostPosted: Fri Aug 29, 2014 8:10 am    Post subject: caps Reply with quote

Thanks guys that's really helpful.

I hadn't thought of just pulling the pistons out enough from the bottom to check the caps!....That will be ideal, I just don't want to disturb the new head gasket I took an age to fit!

....Know where I can get caps from ...or should I turn some up myself from Ali?

Mark
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peter scott



Joined: 18 Dec 2007
Posts: 7113
Location: Edinburgh

PostPosted: Fri Aug 29, 2014 8:46 am    Post subject: Reply with quote

Hi Mark,

I would enquire here first: http://www.singeroc.free-online.co.uk/
Failing that then copy the ones you've got.

Peter
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1939 SS Jaguar 2 1/2 litre saloon
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whiteshadow



Joined: 24 Jan 2011
Posts: 78

PostPosted: Sun Aug 31, 2014 8:44 am    Post subject: update Reply with quote

I could indeed get to the gudgeon pin caps from the sump.

On inspection I had three missing caps........routing around in boxes and tins I found 2 of them. Ordered some Ali rod on eBay...I'll just turn up the final one.

Thanks for the help!

Mark
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peter scott



Joined: 18 Dec 2007
Posts: 7113
Location: Edinburgh

PostPosted: Sun Aug 31, 2014 9:37 am    Post subject: Reply with quote

Hi Mark,

You won't regret the extra work.

Peter
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1939 SS Jaguar 2 1/2 litre saloon
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Old Wrench



Joined: 23 Dec 2013
Posts: 226
Location: Essex and France

PostPosted: Fri Sep 12, 2014 2:43 pm    Post subject: Re: update Reply with quote

whiteshadow wrote:
I could indeed get to the gudgeon pin caps from the sump.

On inspection I had three missing caps........routing around in boxes and tins I found 2 of them. Ordered some Ali rod on eBay...I'll just turn up the final one.

Thanks for the help!

Mark



Personally, I would consider making the buttons (This is what they are called) from PTFE (Teflon) rod.

Readily obtainable: see here:

http://www.directplasticsonline.co.uk/PTFERod

Gudgeon pins are retained by a pinchbolt, in the little end cap, which "nips" into a shallow groove in the pin: or a circlip at the end of the pin; an interference fit in the con rod little end; or a button.

Traditionally, pin buttons were always made from aluminium alloy.

Problem is the button can "Smear" and score the bore.

PTFE is perhaps the best lubricant known and under heat, flows and reforms.

Stressed PTFE bearings become semi-liquid and reset, for example.

Useful article about machining plastics (including PTFE) here:

http://www.google.co.uk/url?sa=t&rct=j&q=&esrc=s&source=web&cd=1&sqi=2&ved=0CDoQFjAA&url=http%3A%2F%2Fwww.ensinger.co.uk%2F17007.file.dld&ei=0vcSVNH5Oamv7AaIp4DYBw&usg=AFQjCNEJJfTtYeSy8LoiR3U2bQ8i2chL_g&bvm=bv.75097201,d.ZWU
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