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

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

Postby ndevans » Mon Aug 05, 2019 7:30 am

I didn't explain properly, my bad. When I put the head on, I torqued it to 40lbft, because that's what I did the after the previous rebuild in 2016. I knew about the 50lbft setting for later engines, and that you need flanged nuts, but I've not got the original nuts or studs now, so no idea which were on.
I gave the head nuts another re-torque, though thinking about it, the engine was cold, after I first spotted the leak. That didn't make any difference, although it did seem to reduce the rate at which the bead of oil formed. I then torqued up to 50lbft, which still didn't cure the leak.

Cheers N
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'69 Traveller, 1275, discs.

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

Postby philthehill » Mon Aug 05, 2019 7:36 am

Thanks for the additional information.
In that case I would remove the head and closely examine the area around the oil transfer passage for both head and block. See what the head gasket is like in that area also. Please report back any findings with photos preferably.
If there is more than 0.003 unevenness or warping of the head/block one or both will need to be skimmed.


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

Postby ndevans » Mon Aug 05, 2019 7:41 am

Ok will do, thanks. Unlikely that I'll get the head off before Weds, so don't hold your breath!

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

Postby ndevans » Mon Aug 05, 2019 10:18 am

How should I check the head and block for distortion? Is a steel rule and feeler gauge good enough?

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

Postby oliver90owner » Mon Aug 05, 2019 10:33 am

That is not a high pressure supply - unless the feed to the rocker shaft is restricted. If not seriously warped, a suitable sealant around that area should prevent any leakage.

A straight edge and a bright light is a good starting point - then only measure any offending areas.

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

Postby ndevans » Tue Aug 06, 2019 12:34 am

Managed to get the head off tonight, wasn't expecting I'd have time, but I did.
There's no smoking gun as far as I can see. The head gasket looks ok, and the surface of the head and block look ok too. Difficult to measure, as I don't think I have a straight edge good enough-my steel rule has a slight curve to it, and my large squares are woodworking squares, and are very old anyway. I have a small engineers square, but it's only 2 1/2", so of limited use. I also have an adjustable square, which isn't too bad. There's nothing obvious when I hold it against the head with a light behind it, though I haven't tried a feeler gauge under it yet.
There are a couple of small spots of carbon on the head surface, and some small spots of dried paint, about the size of a pinhead, that have flaked off the head.
I am thinking I will clean it up as best I can, then refit, torque down, and see if there is still a build up of oil at the same place.

3 questions.

Can I reuse the head gasket? It's been on about 6 weeks, and done about 30 miles.

Does it go on with the copper side in contact with the head, and the other, non-copper side on the block?

I will torque the head up to 40lbft when cold. When I re-torque after the first heat cycle, do I do it with the engine hot, or do I leave it to cool first?

Photos below:-
IMG_20190805_222649~2.jpg
Underside of the head. The leak builds up at the top edge of the head, to the right of the protrusion in the head face, next to the hole for the pushrod.
IMG_20190805_222649~2.jpg (794.93 KiB) Viewed 477 times
IMG_20190805_222806~2.jpg
Head gasket still in place. It may have moved slightly as I removed the head. The oil & water is a small spillage from the head. The leak is at the bottom right edge.
IMG_20190805_222806~2.jpg (1.37 MiB) Viewed 477 times
IMG_20190805_223953~2.jpg
The block surface under the head.
IMG_20190805_223953~2.jpg (767.29 KiB) Viewed 477 times
Cheers N
cheers N
'69 Traveller, 1275, discs.

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

Postby philthehill » Tue Aug 06, 2019 8:00 am

To answer your questions.

Do not reuse the head gasket.

The gasket should be marked top/front.

Use a good quality copper head gasket.

http://www.minispares.com/product/Class ... o%20search

or Payen gasket No: AF460 which is marked top/front.

You can torque the head up either when warm or cold.
The reason for the first heat cycle is that the head/gasket will have had a chance to normalise/settle into it final user position.

Make sure that the head and block faces are spotless.

Lightly grease the head gasket before fitting.


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

Postby ndevans » Wed Aug 07, 2019 12:13 am

Got a new gasket from Moss today. I've also cleaned up the head face with a sharp chisel. How does this look?
IMG_20190806_233856~2.jpg
IMG_20190806_233856~2.jpg (1.46 MiB) Viewed 424 times
Reading the comments above, a blockage in the rocker shaft was mentioned as a possible cause of overpressure, causing a leak. Looking at my rocker shaft (see photo below), I appear to have a screw missing in the second pedestal. According to the BMC workshop manual, there is a screw that goes in the pedestal which locates the shaft in the correct position. I guess if this is missing, the oil hole in the rocker shaft may not be aligned with the passage in the pedestal?
Also, this is pedestal no. 2, but the manual implies it should be the first-is that correct?
The rocker assembly is the original that came with the engine (Marina 1275), but I have transferred it to the big valve Metro head.
IMG_20190806_233832~2.jpg
IMG_20190806_233832~2.jpg (1.13 MiB) Viewed 424 times
Cheers N
cheers N
'69 Traveller, 1275, discs.

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

Postby philthehill » Wed Aug 07, 2019 8:21 am

The retaining peg https://www.moss-europe.co.uk/screw-sha ... soc=137591 for the rocker shaft should be fitted - most important. If the shaft rotates the oil transfer passage can become misaligned and blocked and the rockers/shaft starved of oil and rapid wear takes place.

The original Minor rocker shaft was indeed secured at the first pedestal. It was found latterly that the rocker shaft was prone to breaking forward of number one pedestal because of too many holes being drilled in the shaft. Later 'A' Series engines had the pedestal securing peg moved to pedestal number two and a new rocker shaft with the securing hole drilled in it for number two pedestal. Number one pedestal must have the oil transfer passage otherwise no oil will get to the rockers. See photo below.
Check that the first pedestal has the transfer hole and the rocker shaft is the later type with the securing hole for the second pillar.
If the number one pedestal does not have the transfer passage it can be drilled using the peg pedestal as a pattern. Put a countersink in the bottom of the hole as per picture below so as any misalignment between pedestal and head is alleviated.
100_2631 (1).JPG
100_2631 (1).JPG (1.1 MiB) Viewed 414 times


paul 300358
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Re: Engine in bits for a rebore-anything else worth doing?

Postby paul 300358 » Wed Aug 07, 2019 10:27 am

If it has been run for a while with the peg missing, I would check the shaft to see if its worn. They are cheap to buy and easy to fit.

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

Postby ndevans » Wed Aug 07, 2019 10:38 am

Thanks Phil. Moss are showing the plug as out of stock, which is a pain, as I could drive there tomorrow and pick up a new one. I will use the time by stripping the rocker shaft and seeing how worn it is, and replacing if necessary.

2 further questions. As you can see, I have the sintered type of rocker, not the other type (forged?). They don’t align quite centrally over the valve stems, and looking at the wear pattern, they never have. Is this a problem, and if so, how do I solve it?

Secondly, one of the rockers has a bit of a pit worn in it-can I file or grind this smooth, or should I replace it?

Cheers N
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'69 Traveller, 1275, discs.

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

Postby ndevans » Wed Aug 07, 2019 10:39 am

paul 300358 wrote:
Wed Aug 07, 2019 10:27 am
If it has been run for a while with the peg missing, I would check the shaft to see if its worn. They are cheap to buy and easy to fit.
I was typing as you posted! Thanks.
cheers N
'69 Traveller, 1275, discs.

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

Postby philthehill » Wed Aug 07, 2019 10:55 am

The sintered rockers are designed to overcome the off centre from the valve stem - that is why they are so wide compared to the pressed steel ones. So off centre is no problem - that is how it is.
When the 940 head was originally produced the valve centres were set further apart to overcome the problem with valve seat cracking with the large bore heads pre 940 and so the need for the sintered rockers came about. If in any doubt replace any worn rockers - must be like for like.

The peg is the same throughout the 'A' Series range so even if MOSS do not have it in stock it should be easy to obtain.

ESM have the peg in stock:-

https://www.morrisminorspares.com/engin ... 58-p830384


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

Postby ndevans » Thu Aug 08, 2019 7:35 am

The rocker assembly.....well.....disassembled!
DSCI0424.JPG
DSCI0424.JPG (1.25 MiB) Viewed 348 times
No.1 rocker is at the right. There is some wear on the shaft, and I will replace it. No.7 & 8 rockers are the most badly worn, but all are worn to some extent. I'm toying with the idea of replacing all of them. The oil ways look clear in the shaft and in no.1 pedestal.

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'69 Traveller, 1275, discs.

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

Postby philthehill » Thu Aug 08, 2019 7:55 am

Has the rocker shaft got the hole in it for the locating peg at number two pedestal?


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

Postby ndevans » Thu Aug 08, 2019 9:38 am

Yes, there's a hole where no. 2 pedestal fits. Oil way at no.1 pedestal, top and bottom of the shaft.

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

Postby ndevans » Fri Aug 09, 2019 7:20 am

Charlie Ware's has all the bits I need except the locating plug, which I will order from Minispares. I'll take a trip to Charlie's tomorrow morning after parkrun.
I've decided to paint the head in the meantime. In case anyone was thinking of doing the same-ordinary paint stripper doesn't touch engine paint, as it's already designed to withstand heat!

On a side note-does anyone know what 13J4 means? That's what is cast into the head. There's no 12G number anywhere. I know it's a big valve head, I've measured the valves, and I was told it came off a Metro.

Cheers N
cheers N
'69 Traveller, 1275, discs.

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

Postby ndevans » Sun Aug 11, 2019 6:06 pm

IMG_20190811_142537~2.jpg
IMG_20190811_142537~2.jpg (1.59 MiB) Viewed 249 times
Freshly painted head, with rebuilt rocker shaft assembly.
No, I know I haven't fitted the tappet adjusters yet!
cheers N
'69 Traveller, 1275, discs.

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

Postby philthehill » Sun Aug 11, 2019 10:08 pm

Whilst not all of the rockers in the picture above can be centred over the valve stems several can be improved by the use of spacer washers.
The washers are available in different thickness from the following:-

http://www.minispares.com/product/Class ... o%20search


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

Postby ndevans » Sun Aug 11, 2019 11:41 pm

Won't that screw up the alignment with the push rods?
cheers N
'69 Traveller, 1275, discs.


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