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Jason
Joined: 12 Nov 2008 Posts: 623 Location: Todmorden, Lancs.
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Posted: Tue Aug 12, 2014 4:33 pm Post subject: help needed....piston related |
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I've had some issues with the crankcase pressurising and spitting oil out through the crankcase breather pipe, so today I've began stripping the engine to see whats what.....pics later.
its an Alvis TA14 4 cylinder and after removing the pistons to check the bores and rings....
the bores are glazed and the rings are clean.
there is no sign of a wear lip at the top of the bores, they're just badly glazed / shiny.
now this is where I need a bit of help.....
the pistons are stamped '+0.30' so it has been bored or honed out before.
(the original bore was 74mm)
Do I hone the glazed bores and fit new rings?, if so what size rings? and where do I get them from, I've spoken to red triangle (Alvis agents) and they are unable to help.
Or could I hone the cylinders and reuse the old rings ?
Or do I send the lot to a engine builders and get them to do it?
I'd prefer to reuse my old pistons as there is no sign of any wear or damage.
any help on this matter would be great
thanks in advance
jason _________________ "people with money buy a Rolls Royce, people with taste buy an Alvis". |
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Phil - Nottingham
Joined: 01 Jan 2008 Posts: 1252 Location: Nottingham
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Posted: Tue Aug 12, 2014 6:10 pm Post subject: |
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Thorntons will have the new pistons - find out the cost and weigh up with the use you want out of it. That will clarify your questions _________________ Rover P2
Rover P4
Rover P5 & P5B
Land Rover S2 & S3
Morris Mini Traveller Mk2 |
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V8 Nutter
Joined: 27 Aug 2012 Posts: 588
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Posted: Tue Aug 12, 2014 8:06 pm Post subject: |
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If the bores are in tolerance, a light honing just to break the glaze and probably a new set of rings should sort out your problems. When the engine is running again don't leave it idling for any length of time, the bores will just glaze up again. Take it out on the road as soon as you can. |
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peter scott
Joined: 18 Dec 2007 Posts: 7120 Location: Edinburgh
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Posted: Tue Aug 12, 2014 9:27 pm Post subject: |
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If your rings are intact I wouldn't bother to replace them. Glaze busting possibly since you're in there. Breather design is sometimes not that good at preventing splash from exiting. Check to see if you can improve things with a suitable baffle.
Peter _________________ http://www.nostalgiatech.co.uk
1939 SS Jaguar 2 1/2 litre saloon |
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Jason
Joined: 12 Nov 2008 Posts: 623 Location: Todmorden, Lancs.
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Posted: Wed Aug 13, 2014 5:06 am Post subject: |
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thanks for the replies
Phil, I've emailed Thorntons to see what stock they have and cost
Peter, the rings are intact and look in good condition, I have a honing tool with various grit stones....which grit would be best for glaze busting?
pardon my ignorance, but whats a baffle?
jason _________________ "people with money buy a Rolls Royce, people with taste buy an Alvis". |
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ka
Joined: 03 Dec 2007 Posts: 600 Location: Orkney.
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Posted: Wed Aug 13, 2014 6:35 am Post subject: |
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Use the finest grit, you are just trying to break up the shine, although in my view, if you are not putting new rings on, leave things alone, a mirror finish on the bores is what we should strive for, this gives maximum compression, whilst the cast iron and micro holes retain oil to lubricate.
A baffle is something that stops direct access. In this circumstance, I think there are two ways to go, a baffle made of a ball of wire, so it looks something like those shiny aluminium look scouring pads, this allows air/gasses to flow easily, whilst trapping oil to allow this to run down into the engine, plan 'b', is to extend the breather to above/level with the rocker cover, this means that gravity will reduce the oil flow, then catch the residue in a beer can, chosen to suit liking, but always promotes a conversation. (I use Ruddles County) _________________ KA
Better three than four. |
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peter scott
Joined: 18 Dec 2007 Posts: 7120 Location: Edinburgh
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Posted: Wed Aug 13, 2014 8:09 am Post subject: |
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Jason wrote: | , but whats a baffle?
jason |
I was just thinking of a metal plate that prevents splashes going straight down the breather pipe but still leaving a gap around the edges where air/gasses can pass unimpeded.
Peter _________________ http://www.nostalgiatech.co.uk
1939 SS Jaguar 2 1/2 litre saloon |
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V8 Nutter
Joined: 27 Aug 2012 Posts: 588
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Posted: Wed Aug 13, 2014 7:44 pm Post subject: |
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I have to disagree with with Ka on bore finish. You should be aiming for a cross hatch honing pattern. Too smooth a finish the rings will never bed in and you will have an oil burner.
The old Van Norman portable boring bars produced a finish with very slight pits that supposedly did not need honing, but when I worked in the engine reconditioners we allways honed for finish. First with fine stones, then with cork sticks with gave the optimum plateau honing finish. |
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PAUL BEAUMONT
Joined: 27 Nov 2007 Posts: 1281 Location: Barnsley S. Yorks
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Posted: Thu Aug 14, 2014 1:00 pm Post subject: |
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I entrust this sort of stuff to a proper engine reconditioner. I know it is a bit of a leg for you but I highly recommend Bland's in Barnsley. I have no association with them, but they have done some first class work for me.
Paul |
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ka
Joined: 03 Dec 2007 Posts: 600 Location: Orkney.
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Posted: Fri Aug 15, 2014 7:06 am Post subject: |
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I have no issue with V8 comments, if you are fitting new rings, hone, if not leave well alone. _________________ KA
Better three than four. |
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Jason
Joined: 12 Nov 2008 Posts: 623 Location: Todmorden, Lancs.
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Posted: Sat Aug 16, 2014 11:00 am Post subject: |
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I've decided to remove the engine and rebuild the lot.....new rings, bearings, seals etc etc.....so I will be honing it out.
and whilst its in bits, I'm going to get the clutch relined as well....
I've just got the engine out, so after a brew, a complete strip down will be on the agenda for today...... I'll post some photos tonight. _________________ "people with money buy a Rolls Royce, people with taste buy an Alvis". |
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Jason
Joined: 12 Nov 2008 Posts: 623 Location: Todmorden, Lancs.
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