Engine in bits for a rebore-anything else worth doing?

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Declan_Burns
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Re: Engine in bits for a rebore-anything else worth doing?

Post by Declan_Burns »

Neil,
I had exactly the same problem you are encountering on my MG. I could not get the rings to compress properly with that type of ring compressor which I suspect was a far east product. I used a jubilee clip and had the rings in in a few minutes-and binned the cheap ring compressor.
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Declan


Regards
Declan
philthehill
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Re: Engine in bits for a rebore-anything else worth doing?

Post by philthehill »

Declan
To clarify - did you put the jubilee clip around the outside of the ring clamp at the bottom so as to reduce any spread of the clamp or did you just use a jubilee clip on its own?

My piston ring clamp of the same style is a Draper PRC2 57mm -125mm. The bottom band is 7mm from the bottom of the clamp.

I do not where it was made but I have had it many years and it has always done the job in fitting pistons/rings to large bore blocks.

The other two clamps were manufactured by Terrys and are of the motorcycle type as mentioned above. Again had them many years and never had a problem.

I have just ordered the clamp in the link below which is a copy of the Terry clamp. Made in England too. :D

https://www.ebay.co.uk/itm/Piston-Ring- ... 2749.l2649

Phil
Last edited by philthehill on Mon May 20, 2019 10:38 am, edited 2 times in total.

oliver90owner
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Re: Engine in bits for a rebore-anything else worth doing?

Post by oliver90owner »

Bowie69 wrote: Sun May 19, 2019 10:35 pm The bore/piston next to that one looks ovalled, or is a figment of the camera?

Is it possible the pistons aren't round, giving clearance issues?

Do you have old, suitably sized pistons to attempt refitting ?
His old pistons would ‘fall’ into a rebored block!
Bowie69
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Re: Engine in bits for a rebore-anything else worth doing?

Post by Bowie69 »

Well, I'm not aware of what size they were, nor the reasons why they were changed, I think I came to the party a little late :)
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ndevans
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Re: Engine in bits for a rebore-anything else worth doing?

Post by ndevans »

It's a +0.04" rebore, from standard.

Regarding the clamp, can't remember where I got it from, probably the local car parts shop, so it could well be a far east knock off. It did seem to work ok when new, on standard pistons, but maybe a bit of use has left the clamp a bit more pliable than when new?

One more go tonight, if no joy after a couple of attempts, I'm going to order a new clamp.

Cheers N
cheers N

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33063, Eridge, Sept 2021 by Neil Evans, on Flickr
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Declan_Burns
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Re: Engine in bits for a rebore-anything else worth doing?

Post by Declan_Burns »

philthehill wrote: Mon May 20, 2019 8:43 am Declan
To clarify - did you put the jubilee clip around the outside of the ring clamp at the bottom so as to reduce any spread of the clamp or did you just use a jubilee clip on its own?

My piston ring clamp of the same style is a Draper PRC2 57mm -125mm. The bottom band is 7mm from the bottom of the clamp.

I do not where it was made but I have had it many years and it has always done the job in fitting pistons/rings to large bore blocks.

The other two clamps were manufactured by Terrys and are of the motorcycle type as mentioned above. Again had them many years and never had a problem.

I have just ordered the clamp in the link below which is a copy of the Terry clamp. Made in England too. :D

https://www.ebay.co.uk/itm/Piston-Ring- ... 2749.l2649

Phil
Phil,
On the MG XPAG engine the pistons go in from the bottom as the OD of the con-rod at the big end is wider than the bore. It is a real struggle lining up the crank. Then the piston is pushed up and out of the block, the rings are fitted and clamped and the piston is pushed back down. I tried the clamp without success and was getting quite frustrated until I glanced at the top radiator hose looking at me straight in the face. It had a nice old fat jubilee clip which as it turned out, covered the three top rings. A light tap with a mallet and the bout was over. Plain sailing on the other three cylinders. Some XPAG pistons also have a fourth ring below the gudgeon pin and the only way I can see of fitting that ring, without removing the crank, is with the jubilee clip. I like many others never bothered fitting the lower rings and the car has been fine for the last five years and no smoke.
Regards
Declan


Regards
Declan
oliver90owner
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Re: Engine in bits for a rebore-anything else worth doing?

Post by oliver90owner »

Bowie69 wrote: Mon May 20, 2019 10:19 am Well, I'm not aware of what size they were, nor the reasons why they were changed, I think I came to the party a little late :)
I think the main clue is in the thread title :D
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Re: Engine in bits for a rebore-anything else worth doing?

Post by philthehill »

Declan
Thank you for the reply.

Goodness knows how they managed years ago on those engines which had cylinder head and block as one.

A side step issue - those 4 ring BMC piston that require new rings and there are only 3 ring sets available - the bottom compression ring can be left off without detrimental effect on the engine or oil consumption.

The oil control ring (4th ring) must be fitted.

Phil

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Re: Engine in bits for a rebore-anything else worth doing?

Post by panky »

A chap I know made this to fit the pistons in his Perkins
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ndevans
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Re: Engine in bits for a rebore-anything else worth doing?

Post by ndevans »

Success!

I was going to try a jubilee clip around the clamp, but haven't got one large enough, so I thought I'd try a G-clamp. Before I did that, I tried one more time by hand, this time squeezing the clamp as well as holding it down. After a bit of persuasion, I got the piston in!

I think the clamp is a cheap knock off, so I'm going to order one like Phil posted above.

Anyway thanks for the help, I'll be back when I get stuck next! #timeforabeer

Cheers N
IMG_20190520_205252~2.jpg
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cheers N

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33063, Eridge, Sept 2021 by Neil Evans, on Flickr
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oliver90owner
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Re: Engine in bits for a rebore-anything else worth doing?

Post by oliver90owner »

I think the clamp is a cheap knock off, so I'm going to order one like Phil posted above.

Err, why? The job should be done now. You may never need it again.

Most of my tools have been accumulated over the years as mostly second hand items bought cheaply (well, probably higher quality tools at a price cheaper than modern chinesium rubbish). Only my first Britool torque wrench, the smallest of the range I now have, was purchased new - back in about 1965 - for instance.
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ndevans
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Re: Engine in bits for a rebore-anything else worth doing?

Post by ndevans »

Who knows when I'll need it?
I may not buy one right away, but I will when I need it next.
cheers N

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33063, Eridge, Sept 2021 by Neil Evans, on Flickr
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philthehill
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Re: Engine in bits for a rebore-anything else worth doing?

Post by philthehill »

N
Well done in getting those pistons installed and well done for your perseverance.
I have many tools that have only been used once or twice but they are an important part of my tool kit.
Just when you think that you do not need them anymore a job will pop up and you will be glad that you have the tool to do the job.
There is nothing worse than not having the right tool to do the job.
A good move in my eyes purchasing another clamp.
The motorcycle type clamp in the link above can be supplied in different sizes. If that is the clamp you are considering - make sure that you get the right size for your pistons.
I would advise that you purchase the clamp now as it may not be available at a later date as I have found to my cost.
I have ordered the motorcycle type clamp and yet currently I do not have any 74mm pistons for it to work on - I just need the clamp to be there and available when I come to fit the pistons. A bit of forward planning at work. :wink:

Again well done.

Phil

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ndevans
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Re: Engine in bits for a rebore-anything else worth doing?

Post by ndevans »

Thanks Phil.

I'll probably go for the other clamp you posted, I think the one I have is an imitation of that. There's nothing worse than having a job to do and not having the right tool to hand! Quality tools are just as worthwhile as quality parts!

Cheers N
cheers N

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Re: Engine in bits for a rebore-anything else worth doing?

Post by ndevans »

philthehill wrote: Thu May 16, 2019 8:27 am Crankshaft end float should be 0.003" - 0.004" and is set by the thrust bearings either side of the centre main. Make sure that they are fitted the right way round.

The thin washers at the front of the crankshaft set the alignment of the timing gears only.

There is no seal at the rear of the crankshaft just the return scroll.
I measured the endfloat at north of 0.006", could just about get 0.008" in there. So I ordered 0.005" oversize thrust washers, but I can't get them in. The crankshaft will not sit in the bearings properly with the lower thrust washers in.
Is it ok to use a +0.005" on one side, and a standard thrust washer on the other side of the centre main bearing?
If not, is it ok to run the thrust washers over a flat sharpening stone to take a little material off them?

Cheers N
cheers N

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Re: Engine in bits for a rebore-anything else worth doing?

Post by philthehill »

It is perfectly satisfactory to use different thickness thrust washers either side of the centre main to achieve the correct crankshaft fore and aft float.

You can if required place a sheet of medium wet & dry on a sheet of (safety) glass and with the paper lubricated with WD40 (or similar) and rotating the thrust washer in a figure of eight reduce the thickness of the bearing face to suit.
100_2162.JPG
100_2162.JPG (972.73 KiB) Viewed 2150 times
Re-check alignment of the timing gears and adjust if necessary after correcting crankshaft end float.

Whilst on the subject of end float - the camshaft should have 0.007" end float.

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Re: Engine in bits for a rebore-anything else worth doing?

Post by paul 300358 »

Blimey, I wish I had thought of that!! Eventually, I will drop the sump for a clean and will have another look at the thrust washers as the end float was 0.006" but 0.005" would not fit. Are you removing metal from the face or the back of the washer?
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Re: Engine in bits for a rebore-anything else worth doing?

Post by ndevans »

paul 300358 wrote: Mon Jun 03, 2019 9:39 am Blimey, I wish I had thought of that!! Eventually, I will drop the sump for a clean and will have another look at the thrust washers as the end float was 0.006" but 0.005" would not fit. Are you removing metal from the face or the back of the washer?
I'd assume you remove from the face, not the back of the washer.
cheers N

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33063, Eridge, Sept 2021 by Neil Evans, on Flickr
'69 Traveller, 1275, discs.
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ndevans
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Re: Engine in bits for a rebore-anything else worth doing?

Post by ndevans »

philthehill wrote: Mon Jun 03, 2019 7:35 am It is perfectly satisfactory to use different thickness thrust washers either side of the centre main to achieve the correct crankshaft fore and aft float.

You can if required place a sheet of medium wet & dry on a sheet of (safety) glass and with the paper lubricated with WD40 (or similar) and rotating the thrust washer in a figure of eight reduce the thickness of the bearing face to suit.

100_2162.JPG

Re-check alignment of the timing gears and adjust if necessary after correcting crankshaft end float.

Whilst on the subject of end float - the camshaft should have 0.007" end float.
Thanks again Phil!

In a rare moment of foresight, I ordered some spacer washers for the timing chain sprocket when I ordered the thrust washers!

Are spacers available for camshafts?

On the subject of camshafts, is there any difference between having a cam reground to a profile, and a new one made to that profile?

Thanks,
Neil
cheers N

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33063, Eridge, Sept 2021 by Neil Evans, on Flickr
'69 Traveller, 1275, discs.
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Re: Engine in bits for a rebore-anything else worth doing?

Post by panky »

From the back of the bearing, I did this when I re-built my Mini engine.
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