12G940 cylinder heads

[246gts]

Bottom end of 1275 Ital? engine has been checked over by local machine shop and is in qute good order so that should be sorted by next weekend. However the cost of them doing an unleaded conversion to cylinder head is very expensive and it would seem cheaper to buy an exchange head.
The question I have is are all 12G940 heads the same? There are quite a few on eBay from Minis but are these direct replacements or are the valves etc different. I intend to rebuild bottom end to Ital standard and maybe put an MG metro cam in so which heads would be suitable.
Any ideas please
Dave

[rayofleamington]

Hi,
There a re a few different versions of 12G940 with slight differences in valve size and there is even an 11 stud version (as far as I remember)

If you're going for a tuned engine then get the engine tuner who is doing the porting and polishing to add the hardened seat inserts.
If you're going for a standard head, then it won't make a huge lot of difference which one you get.

Cheapest option is to run with the existing head - if/when you get valve seat problems - then you can get the head exchanged for an unleaded one! Bear in mind that you can often run for years without problems.
If you're not going to do more than ~40,000 miles in the car it'll be cheaper to use an additive than change to a recon unleaded head anyway. (I use an additive as my Minors rarely do more than a few thousand miles a year and I have too mny to think about buying unleaded heads all the time)

[Packedup]

I flogged an unleaded Metro head to someone on here for either 35 or 40 quid, can't remember now. As far as I know it's going strong and fitted fine (other than non-Metro related problems ).

As Ray says, there are differences in valves and suchlike between various models, but any unleaded 12g940 will do - Some are just slightly better for certain applications than others. There might be improvements in the MG Metro (and also 90s Mini Coopers as I think they use the same basic bits?) head which would be more suited to the cam you're thinking of, but I honestly don't know.

[rayofleamington]

try this:
http://drcwww.kub.nl/~bogaard/heads.htm

[bmcecosse]

The early MG Metro heads had bigger inlet valves and throats - as did the few of these 940 heads that were fitted to Cooper S engines - these have 11 stud holes - but you don't need to use the extra 2 holes. All unleaded heads (including the Cooper) are exactly the same - no advantage in any of them. The MG Turbo head has very special (= expensive) exhaust valves and no advantages. Avoid it!

[Stig]

Just a thought as this came up once before, do they all have the hole for the heater valve at the back of the head? OK, you could drill one yourself but it'll be less hassle to get the right head in the first place.

[bmcecosse]

They should all have the two threaded holes to hold the valve on - but the middle part is solid - just needs a drill pushing through. Many of these heads have NO bypass hose connection. This is a good thing - just need to either use a pump with no connection, or plug the end of a bypass hose and fit it to the pump. Then either keep water flowing through the heater all the time (it now works much better!) or drill 2 holes each 1/8" in the thin rim of the thermostat.

[TwincamTurbo52]

One cheaper option is to use the maestro 1.3 head, all unleaded and utterly worthless compared to the (still cheap), mini heads.

MG metro heads had the larger valves and a small machining proceedure in the inlet throat, but this is only worth 3-4 hp and it's easy to fit a larger inlet valve if you want to.

[bmcecosse]

But the bigger valves are not cheap - whereas I bought 2 MG Metro heads last year for £20 each - both in fine order.