Please measure your 948.

[bmcecosse]

Plenty on ebay!! You don't need to be too fussy about the exhaust valve seats - since you are going to recess them anyway. We did this at work using a 45 degree countersink in a pillar drill. Just let it self-centre on the old seats and then cut down by 40 thou. It took less than 10 mins to do all 4 seats. The head I used cost me £10 !!

[rayofleamington]

'fat' sintered rocker arms - and these just straddle across the different pitching of the exhaust valves.

These rockers were used on hundreds of thousands of engines and work fine - certainly not preffered for high tune engines, but then neither are most of your standard engine bits.

Rog - if you get stuck I'm pretty sure I've got a spare set of the sintered rockers. The fit straight on with no faffing about aligning anything. I picked them up at an autojumble just in case I ever got a 1300 head on a Minor again.

patgarrett,
Depending on the 12G940 head you get, you may not have to machine anything. The one's I've used (on a 1098 and on a 948) didn't need the valves recessing as the valves had worn there way into the seats enough. A very good condition 12G940 head would need atleast 40thou taking off the seats.
If you're going to get it machined, it's possible to get this done at the same time as having unleaded seats put in (the machinist would just need to know that you need the valves seated deeper). That would kill 2 birds with one stone.

I'm waiting with baited breath to find out how Rog gets on with the 12G940 head on a MINOR 948 block. Getting the water jacket to seal isn't as easy as some people think. Will be interesting to know which make/number headgasket suits his parts.

[patgarrett]

If you're going to get it machined, it's possible to get this done at the same time as having unleaded seats put in

Hi, just bought a 12G940 head on ebay for £26 (sorry if I out bid anyone). It has already got unleaded seats as it is off a late Metro.
How can you tell if the valves need sinking in and by how much?
Is it just a case of measuring from the sealing face of the head to the valve face?
If so what dose this measurement need to be?
Would I be right in saying that it's to do with valve lift and clearance from the block, the Haynes book says that on a 1098 it is 7.925mm. Please help as this is the only thing I am unsure on. Many thanks to all Pat.

[RogerRust]

The inlet valves are fine they clear the block and go down the bores.
Its the exhaust valves what I aimed for was 8mm of gap between the valve face and the face of the head. The engineering shop did this with three angles so as not to shroud the valves. Total cost about £40.
But you will need to be careful with unleaded seats not to cut too much out . I expect somone will be along soon with some more info.

[RogerRust]

Ray;

I have a set of rockers like these,


Can I use them even iff they don't quite line up? I'll strip and clean them later today and see what's the best I can do for allignment. This would certainly be an easier option if its ok.

[bmcecosse]

Yes - as I said already - that's what Rover did - they just straggle across the different valve pitches. But it's not ideal !! However - it works. I have never had any probs sealing the head down to the block - however there is one waterway in the block which quite obviously has no match in the 1275 gasket or the 1275 head. I simply put a blob of silicon sealer in this and then sat the gasket on top. I do this mainly because the gasket has no reinforced 'ring' around that hole - and so there must be a chance of water squeezing sideways along the surfaces. No problems with it in the past - or present.
Pat - the early 948 engine camshaft has less lift than the later 1098 camshaft. Therefore a 948 cammed engine can be used with a 940 head without doing anything - but if a 1098 cam (or MG Metro cam which is better) is used (in either 948 or 1098 block) - then you DO need to lift the exhaust valves into the head by 40 thou to get clearance. If you think they are 'worn' by 40 thou - then fine - try it and see. It has to be said some exhaust valves also have a 'thinner' head than others - and this also has a bearing on the clearance available. Simple check is to put a blob of plasticine on the block and do a trial assembly - turning the engine over by hand. Then look to see what's happened to the plasticine. There is an alternative - much beloved by the Mini lads - of grinding little 'pockets' into the top of the block under the exhaust valves. I feel heads are plentiful and cheap - Minor engine blocks are not so plentiful, and it's less messy to modify the head anyway!

[patgarrett]

Top advice, thank you, I just have to wait for the head to turn up (pos friday) and then set to reconning it and away I go. I also had a look at the back plate on my 1098 and there's nothing to be done to that but the water pump will need a bit of a file. Then we have the fun of putting the rockers in line with the valves, Nothing to taxing. There was one thing I was wondering and that's will the top hose line up with the rad or is a differant thermostat housing needed. Sorry to be asking so many questions but I like to have all the parts to hand before I start.

[bmcecosse]

Ah - no you will need to use a slightly longer top hose - with a bit of a bend in it. I think I cut up a bottom hose (probably a Mini one - but v similar to Minor ) and used that.

[rayofleamington]

There was one thing I was wondering and that's will the top hose line up with the rad or is a differant thermostat housing needed. Sorry to be asking so many questions but I like to have all the parts to hand before I start.

The convoluted top hose will fit, and it does work, but the hose is quite stressed and it looks wrong. I ran one like that for about 20 thousand miles without problems.
The Better option is to get a thermostat housing from B-series marina (or equivalent MG). These have a different exit angle for the pipe and cures the misalignment.



The B-series part is not available new, but someone posted a link for the MG part, which can be purchased from the US, and was not too expensive.

[patgarrett]

Hi, just bought one of the thermostat covers as above off ebay new from the US for £10.98. There is a link to to this seller on a thread under useful tips.