Morris Minor Owners Club

The 'bullet' is the oil pressure relief valve - there should be a spring too - and the hex plug that holds them in the block - over beside the dizzy and the oil pressure switch. The plug you show (if not sump drain) then it's likely the plug for the priming port for the oil pump.

bmcecosse wrote:The 'bullet' is the oil pressure relief valve - there should be a spring too - and the hex plug that holds them in the block - over beside the dizzy and the oil pressure switch. The plug you show (if not sump drain) then it's likely the plug for the priming port for the oil pump.

I think the plug is more likely the coolant drain - if I remember right, the 1098 engine doesn't have the oil priming plug

Some do - some don't.

Hi all,

Many thanks for the replies. I have now been to the engineering shop, prepare for some controversy....

I explained what I wanted to do RE fitting the 12G940 to the 1098 block, this immediately raised cries of 'can't be done, the valves hit the block'. I explained about sinking the exhaust valves to allow for .320 clearance, but this was declared not correct, and that the block should be pocketed to allow for the correct clearance. To ascertain the correct clearance the engine would have to be dry built, and turned with a dial gauge attached to measure the amount needed to be taken off the block! This was the opinion of two professional classic engine builders, both of whom are specialists in building A-series engines for race and road, so I felt a bit stupid saying 'you're wrong, I read it on the internet'....There is certainly an element of 'this is the correct way to do it, so this is what we shall do'

So, in the light of this, could anyone please advise me how to measure clearance from the face of the valve to the head, it hasn't been skimmed yet. I currently have no accurate measuring tools but I will go and buy what is required if its a useful item.

It would also be great to hear from others who have completed this job, if you could tell me exactly how you achieved the correct valve clearance, in as much detail as possible would be fantastic! Then I can return to the engineers and maybe just instruct them to do it, whatever they say. Having the block pocketed is only £40 plus the vat.

I was also shown a hole on the face of the block, I think for water, that is covered up by the 1275 head gasket, and was told that this would need to be blocked up, as its too close to the edge of the gasket (bore edge) so water can enter the engine. Any thoughts on this?

I'm just a bit concerned I'm going to end up spending £100s on an engine I'll reassemble myself so no guarantee, I could easily make a mistake as I've never done one before, and waste all that money! When a fully reconditioned engine from them is £915, standard though.

Thanks all,

Edd

Ed
I have to agree with the engineering shop in that the correct engineering way for fitting a 940 head onto a small bore block is to pocket the block.
This will alleviate the question as to whether the valve has been sunken sufficiently into the head.
If they have done this before and by what you say they have - they should know exactly how much to take out of the block and the pocket orientation in the top of the block.
I personally would not even consider sinking the valves to get over the valve problem and think that £40 will be well spent.
I am not sure what they are on about regarding the gasket and blocking a water passage; as the fitting of the 940 head to a small bore engine is a well trodden path.
In the mean time I will try and find out more regarding head gaskets and water ways.
Phil

In pure engineering terms pocketing the block is the correct way as I see it. Although as we often hear sinking the valves is a way round it, simply because it's a diy job, rather than preferable. The place giving you advice may have some difficulty in being persuaded to do something they don't consider right. I seem to recall 60thou being the figure to 'sink' the valves so presumably that amount would be taken from the block, however that needs to be confirmed, and as mentioned the figure should be known by the company recommending it.

Thanks Phil!

Stupidly I didn't take a picture. The chap placed a 1275 gasket on the 1098 block, this covered a water way hole, which was close to the corner-edge of either cylinder 1 or 4. Sorry it was hosing it down with rain and we were rushing to get the bits inside also, hence not enough attention being paid. He said that this was too close, and water could make its way into the cylinder. Therefore it would need filling, he didn't give a price.

I thought that pocketing the block was a big no-no, but I am happy to pay the £40 if it will be ok. Has anyone done it? Block is being bored to +060 if they cannot get +040, so it will likely not be used again. That also allows me to consider a higher-lift cam, any thoughts for torque? I only rev to 4000 or the gearbox is too noisy! haha.

Many thanks,

Edd

EDIT - Les, thanks for your reply, I very much got the idea that they felt pocketing the block was the correct engineering method, so thats the way they would do it

There is no problem in the gasket covering a water transfer passage but it does concern me that a water transfer passage is very close to the edge of the gasket which could lead to water entering the cylinder.
Fitting a water passage blanking plug (if required???) is not difficult and should not cost the earth to do.
As regards the high lift camshaft - the further you stray from using standard components the more the chance you will require a dry run to determine clearances so adding to the overall cost.
Even if you bore to plus 0.060" you can still use/recondition the block by having liners fitted.

Thanks Phil!

Yes having spoken to Minor Millennium, it seems a blanking plug is no biggie. They will also sell me an exchange unleaded 940 for a decent price, and they have checked it has the necessary clearances.

On another point, I am having the block dipped to properly clean it, apparently this will destroy the cam bearings so new are required. £80 to fit, sound reasonable?

Thanks,

Edd

If it includes line boring, probably reasonable. Where are you getting the block dipped, I can't find anywhere that use chemicals only a soap solution, there used to be a tricolethelene (spelling?) dip that got every bit of oil/ grease off, virtually as soon as the part entered the tank. I think H&E put a stop to that one.

Pocketing the block - ruins the block for future use, and exposes the top ring to excessive heat. DON'T DO IT! You may not even need to sink the valves - measure the distance from valve top to head face - you need 300 thou, the 320 includes a 20thou margin of error, and the thickness of the gasket is also there for safety - not included in that 300thou. Plasticine and a steel rule is one way - certainly no need for 'dry assembly' etc etc - just measure the head. The additional flow with the 1275 head so easily out weighs any supposed 'loss' due to sinking the valves - if you need to do it at all . (in fact - Calver once published an article that claimed there was a power increase from sinking the exhaust valves - although I take that [like all Calver's rants] with a huge pinch of salt. It's also a simple job to do - 5 minutes with a 45 degree countersink in a pillar drill... But as above - you may not need to do anything if the valves have recessed themselves. The 1275 gasket works perfectly well - many many have done the job and had absolutely no water leak or gasket problems and without 'plugging' anything. These guys are just trying to make work for themselves - and are not up to speed with the very easy and economical way to do this job. Just go elsewhere - a place with a pillar drill and a countersink is all you (may) need. The only caveat is that you must not use a high lift camshaft - or high ratio rockers - but then , there is no need for these things anyway!

Can't help on the technical stuff,but gut feeling is that this could be a money pit. I'd swap the engine.

I skimmed the exhaust valves (inlets dont need to be touched) and have had no trouble at all. The valves are particularly chunky and even taking off .020" there was still plenty of meat left on them. I measured the distance by placing a straight edge across the head and used the depth gauge end of a vernier to measure then subtracted the thickness of the straight edge to get the clearance. It mightn't be the recognised way of doing it but it works and others have had good results.
A compromise, if you're nervous about taking too much off the valve face, is maybe a combination of sinking and skimming.

Exhaust valve after skimming

And I'm guessing (like me and many hundreds of others) you had no problem with the head gasket?

None at all, used the 1275 one and no issues. The head came off again after a few thousand miles to do the valve guides and everything was perfect.

Nothing like a mix of opinions!

Thanks for the replies all, I will forward the concerns of top ring being exposed to too much heat to the machine shop and see what they say. They are a builder of top-end mini race engines, whilst I was in there the chap showed me a titanium con-rod, £1000 and they only last 9 hours, so yes there probably is an element of over-working what will only be a 'brisk' road engine.

BMC I did tell them that others had success with a countersink and a pillar drill, their response was to query how it was kept accurate and perfectly in line, without the valve guide to use to line up?

If I didn't want a money pit I wouldn't have bought a Morris Minor! You think the engine is bad, should see the bodywork list I've got.

Will update when I get any info from the machinists.

Thanks all,

Edd

EDIT - Interesting regarding the head gasket, again maybe more of a problem on higher-spec engines? I will get a costing for a brass plug, I can't imagine it will be much. If its dear then I'll tell them not to bother

You're going to the wrong place.....and if they can't see that the 45 degree countersink SELF CENTRES on the seat - then I wouldn't trust them to polish my shoes... The countersink is only revolving slowly - the head is constrained to stop it 'spinning' but is NOT fixed down to the table - and - top tip - put a piece of emery paper in with the countersink to prevent chatter. Result is beautiful smooth grey seats. Seriously - go elsewhere. They are obviously used to working on high end (and extremely high cost) cars/engines. You are looking for a budget solution - and they are not the people to do it. But MEASURE FIRST - you may not need to do anything.

They obviously like doing things the right way, can't fault them for that! Less precise ways of doing things have been mentioned and seem to work for many, it all depends on the individual.

£40 to pocket the block is hardly 'extremely high cost'! Sounds like a good solution to me. It would cost that much in labour to sink the valves, or likely much more to buy what's needed to do it oneself! The prices quoted sound quite reasonable to me. As Les said, I think this boils down to personal preference. Vizard, who everyone seems to regard highly, advocates pocketing the block, and I think he's a reasonable engineer, so it can't be such a bad idea

To pocket the block it will need to be stripped down - and then rebuilt of course, after a very thorough cleaning. Perhaps you had planned that anyway. And it will STILL expose that top ring to excessive heat ! And it ruins the block for further use. The simple head job to sink the valves is really only a 5 minute job - and if need be in the future - the head can be reconditioned by fitting 'unleaded' seats. By the sound of your comments the 940 head conversion is the least of your worries - sort out the body/suspension/brakes first!