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Wm20

Having taken the head off my 1940 wm20 I noticed that it had been sleeved at some time , I noticed that the sleeve is about 3mm below the top of the bore , I would have thought that it should be flush accross the top . Could someone please heip me out regarding this queary , If it should be flush is there any way to correct the problem ? Any way it could be pressed back up .any help would be gratefuly recieved .thanks Win.

Re: Wm20

The war time period barrels were not considered as top notch castings and all were fitted with a liner at the factory. At some point post war the barrels were of better quality and no liner was fitted.

The liner has a flange at the top which sits in a corresponding recess. I don't know what has happened to yours, but it should be possible to press it level again,..... but will it stay there? Ron

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email (option): ronpier@talk21.com

Re: Wm20

If your liner has moved Win, I would have have a new custom liner made and fitted. This time use a liner with a flange on it.

If you get stuck I can do this for you.

email (option): pes.sales@btconnect.com

Re: Wm20

As Ron notes the liner should have a shoulder at the top that fits into a machined recess at the top of the barrel...Liner creep can occur on an M20 and this usually manifests itself in the form of a part of the shoulder breaking off the liner...
Pressing it back into place won't really provide a workable solution as any potential problem has not been addressed and your liner has sunk way beyond the normal...

I would firstly remove the liner entirely to determine whether a parallel liner has been fitted at some point and to examine the machined recess (if it's still there) within the barrel...The barrel can then be accurately measured to determine its diameter without the liner...

It seems hard to imagine that the recess in the top of the barrel will still conform to the original dimensions (if it's there) as the liner seems to have moved by an amount that would make that impossible...

So, you really need to see what you actually have after the liner is removed. There is plenty of material in an M20 barrel to remachine it for a liner that meets all the criteria required in terms of shoulder, fit etc. and there are multiple liners out there as 'donors' along with custom made items...
If it comes to that look for a liner that has the shoulder dimensions you need, or a shoulder that is large enough to be machined down to what you want...Then, if you can't get one the right length go for one that is longer...The bottom of the liner can be easily shortened...
Finally, go for an outside diameter that can be used without alteration..Altering the outside of a long liner can produce parallelism problems....Westwood Liners are the people I usually go to...If you have the basic dimensions you require they will look in their extensive listings for one that will do the job or can be modified as I described earlier...

Firstly, however, I'd recommend you remove the existing liner so the 'dog can see the rabbit'...Ian

email (option): ian@wright52.plus.com

Re: Wm20

email (option): pes.sales@btconnect.com

Re: Wm20

Thanks for all the info , after cleaning the top of the barrel off I came to the conclusion that the amount of drop in the liner was not as much asI first thought more like just under a mm.
Any way I took it to a local machine shop where he said it wasn’t too bad so he pressed it back to the correct position, What I think I need to do is to pin it to stop it happening again , What do you think ?.
Thanks again all for the very interesting information very much appreciated .Win.

Re: Wm20

The job wants doing properly in my opinion, but not by the machine shop you visited. Good luck.

email (option): pes.sales@btconnect.com

Re: Wm20

I have seen engines that have been running OK with this amount of liner drop and on that basis you could have ignored it...However, that would be a gamble as the liner has moved, so obviously there is an issue with the fit...If a piece of the shoulder does break off due to the pressures being exerted on it the piston, rings, cylinder bore, valve(s) and seats are all potentially at risk of damage from the piece that has broken off being loose within the combustion chamber...I should note here that I've seen and had to repair this type of damage more than once...

'Best practice' is always the correct, if not the easiest or cheapest, course to follow and the procedures for putting this problem right have been detailed in previous posts...I agree entirely with Mark on this one, including his comment about your machine shop who have already failed to give you sound advice IMO, or maybe they just did what they were asked to do?......Ian

email (option): ian@wright52.plus.com

Re: Wm20 sleeve

Ok Thanks again All , well I have a decision to make eh, sounds like there’s only Only one proper one . As we say here in Oz she’ll be right .
Hope that you are all keeping c19 away . Win.

Re: Wm20 sleeve

I have seen a 350 Gold Star eat a liner that was of course wron and slid down the bore.
The con rod then chomped off bits till eventually one of the bit gat stuck between the rod & the flywheel web,,,,, not pretty.
So remember there can be unforseen consequences

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