1275 Head

Post by **honda90** » Sun Nov 30, 2008 2:17 pm

Are the 1275 heads from mg midget the same as the ones on 1275 ital A+. My present head on my minor with 1275 A+ engine has a leaking exhaust valve, someone near me has a nearly new unleaded mg head for £70 they look the same just wanted to check.

Post by **Peetee** » Sun Nov 30, 2008 4:01 pm

In terms of fitting there is no difference. The only thing you need to check is if there is a bypass hose below the thermostat. Technically there are two varieties of 12G940 - the difference being in the valve sizes. The larger valve head was fitted to the MG metro (not turbo) and (if I remember correctly) later A+ engines.

Post by **glyna2006** » Sun Nov 30, 2008 5:03 pm

the engine if its A+ you have in your car is probably a marina with the oil filte facing up,if that is so its the same as ital the maestro's also had these heads in unleaded form..regards glyn

Post by **bmcecosse** » Sun Nov 30, 2008 5:19 pm

The 'unleaded' MG heads do NOT have the larger inlet valve - only the earlier 'leaded' heads had that larger inlet valve size. So yes - that head will fit (if no bypass then that's a bonus!) - it's up to you to check if it really IS unleaded, and if it's worth £70 ??

linearaudio · Post by **linearaudio** » Sun Nov 30, 2008 6:06 pm

bmcecosse wrote:The 'unleaded' MG heads do NOT have the larger inlet valve - only the earlier 'leaded' heads had that larger inlet valve size. So yes - that head will fit (if no bypass then that's a bonus!) - it's up to you to check if it really IS unleaded, and if it's worth £70 ??

Certainly sounds a bit pricey, mine was less than half that from a breaker, and unleaded. Guess it's local supply and demand though!

Post by **bmcecosse** » Sun Nov 30, 2008 6:20 pm

Not for me to say - who knows - there may be a rule about it!

Post by **glyna2006** » Sun Nov 30, 2008 6:40 pm

25 quid i paid for maestro one it had the ron95 sticker on slam panel...only thing i took it off my self and it is still in my shed the unleded heads have hardened inserts if u put a file to the inserts they don't mark,a lot are stellite steel.Slightly smaller inlrtt valves on this head compared to the mg metro one ,I've run my convertible for the last 10 years using only addative but don't do big milage,i checked tappets the other day and not one has gone tight so no ressecion...rgards glyn

Post by **bmcecosse** » Sun Nov 30, 2008 6:42 pm

You don't even need additives - unless doing long hard miles.

Post by **glyna2006** » Sun Nov 30, 2008 7:37 pm

what about to Malta? but would loose my big valve head 1800 miles one way...

Post by **bmcecosse** » Sun Nov 30, 2008 8:17 pm

I would class driving to Malta as 'long hard miles' !

Post by **Kevin** » Mon Dec 01, 2008 10:41 am

Certainly sounds a bit pricey, mine was less than half that from a breaker, and unleaded.

This has gone a little astray as John was asking about the Midget head against an A+ head.
Well according to my books all the Marina, Ital A+ & Midgets have the same size valves.
Inlet 1.307" to 1.312" (33.198 to 33.21 mm)
Exhaust 1.1515" to 1.1565" (29.243 to 29.373 mm)
And if the Midget one is unleaded it will have been converted as they were not produced unleaded, as for the price Midget heads do go for more money and as its nearly new that doesnt seem to bad as they are much dearer than that when reconditioned.

Post by **bmcecosse** » Mon Dec 01, 2008 11:18 pm

There's no logic for 'Midget' heads going for more money - but I dare say it's true! They are indeed the same head as many others.

Post by **XDB** » Sat Jan 10, 2009 9:36 pm

I have been looking for a 12g940 for ages, I found one on ebay local to me its off a 1275 metro without the bypass hose spigot. The price is £40 for a bare head no valves or springs. I think its a bit pricey so I will have to carry on looking.

I am a bit puzzled about the by pass hose I know either a head can be fitted, but which is best? with or without.

Post by **bmcecosse** » Sun Jan 11, 2009 6:39 am

For me - without! It's something less NOT to go wrong. And - it gives very much quicker heater response on starting from cold. Rover eliminated for a good reason.

Post by **FrankM83** » Sun Jan 11, 2009 10:30 pm

what's the advantages of a 1275cc head?

Post by **bmcecosse** » Mon Jan 12, 2009 7:57 am

Bigger valves, better combustion chamber shape (much less 'masking' of the valve heads) and much better air flow through the larger ports and throats. The chamber volume is also smaller, rsulting in higher Comp Ratio without need for skimming. Effectively it is a 'Stage 3' head for a 1098 engine - 'Stage 4' for a 948!