12 replies to this topic

[Twincam]

Model: Rover Mini City E

Year: 1990

Hi Guys, (hope this is the right section of the forum)

I've recently bought another Mini but soon learn't that the engine had infact been swapped some time in its life to a 1275 lump.

I've searched the net and found that the engine was in fact a Standard Metro (Pre October '84 low compression unit) with the numbers 12H907AA stamped into the plate. I also have a 12G940B Mini SPi head and have a few questions as follows...

1. Would the 12G940B give me any peformance/running gains over the standard head?
2. Would it be a straight fit (apart from the bypass hose needing to be blanked off and thermostat drilled)?
3. When did the heads start becoming Unleaded?
4. What does it mean when it says its a low compession unit?

Also, I saw a central oil pick up pipe on eBay and don't really have a clue about them... (Just thinking before I assemble the engine if theres anything which is worthwhile putting in there). Are they worth it?

Thanks in advance,

Hasan

[Twincam]

Anyone?

[mars red mike]

1. Would the 12G940B give me any peformance/running gains over the standard head?
Unless the head you already have fitted is worn, no you wont see any increased performance. (Assuming the SPi head is standard of course)
2. Would it be a straight fit (apart from the bypass hose needing to be blanked off and thermostat drilled)?
Yes its a straight swap apart from what you have mentioned.
3. When did the heads start becoming Unleaded?
Unsure of the exact year but all injection engines were unleaded.
4. What does it mean when it says its a low compression unit?
Not totally sure. I think its something to do with the dish of the piston but maybe totally wrong.

Also, I saw a central oil pick up pipe on eBay and don't really have a clue about them... (Just thinking before I assemble the engine if theres anything which is worthwhile putting in there). Are they worth it?

Ive not had any experience of them personally. Some people rave about them, others hate them. Better answered by someone who has got one

[Twincam]

Thanks for your help, hopefully someone will be able to go into more depth regarding the low compession unit.

Hasan

[bmcecosse]

If you intend doing any rapid cornering - you NEED the center pick-up pipe! The head should fit ok - but won't be any better than the standard head.

[Twincam]

If you intend doing any rapid cornering - you NEED the center pick-up pipe! The head should fit ok - but won't be any better than the standard head.

Are the heads basically identical apart from the sleeves being able to withstand the unleaded fuel (and the bypass hose)?

[wile e coyote]

12G940B is the std unleaded 1275 head - essentially the same as you'd have with a standard 1275 12G940 (valves in the early leader MG versions are bigger and i think the ports are fractionally improved in those) to run a "B" suffix version in addition to the bypass take off (if you need one???) / holes in thermostat , the majority of these heads have no tapped hole for a temp sender (only ever seen one that did - balnking plug fitted) - a reasonable machine shop will tap this for less than £20 . You can easily drill out the hole for the heater tap the mounting stud threads are already there and tapped...

[bmcecosse]

You can get a thermostat cover with temp take off tapping - no problem there - but there seems no point/advantage in this head swap . Why are you thinking of it ?

[Twincam]

You can get a thermostat cover with temp take off tapping - no problem there - but there seems no point/advantage in this head swap . Why are you thinking of it ?

I bought it as it is unleaded and already for me to just plonk onto the Metro engine - not sure if the Metro lump has the 12G940 head on it? (or was there only two types?)

Was the original temp sender in-built within the ECU unit on the SPi units?

Edited by Twincam, 11 January 2010 - 09:10 PM.

[bmcecosse]

Don't worry about 'unleaded'! Just set exhaust gaps to 15 thou - and check/reset them every 3000 miles. It will be fine.

[Twincam]

Now you tell me!

In regards to the SPi head, should I keep it as spare (I do have a Cooper SPi too) and maybe modify it (gas flow/port it) or off load it?

[bmcecosse]

Certainly keep it - useful spare - prices certainly not going down!

[Twincam]

Certainly keep it - useful spare - prices certainly not going down!

Thanks for that, by the way do you know what it means when it says the unit is a Low Compession Engine?