Lund's MG Metro 1275 Engine Build
Discussion
Hi all,
I now have an A+ MG 1275, a Metro 1275, and a 998! The MG metro comes with all ancillaries electronic ignition, HiF44 cone filter etc etc, but is without a gearbox. However, the Leyland 1275 has a gearbox but no diff. The 998 has a diff, but the engine isnt in good health! So, I intend to use the box off the 1275 and the 998 diff - will the box mate to a A+ MG block? Also, will the diff suffice and take the power of the MG 1275, which I hear is 72bph @ 6000rpm as standard
The MG metro also has a high lift cam and was rolling roaded before it was removed from a Mini, due to gearbox problems. It has covered approximately 55,000 miles in total. However, the cam is unknown, but I was told that it idled smoothly and ran sweetly.
I'm wanting to spec the engine for acceleration more than top-end speed.
What sort of power output will I be looking at with an MG Metro 1275, electronic ignition, MG alloy inlet, HiF44 carb with K&N, Cooper freeflow exhaust, with straight through Rc40?
One other question: Can I legally use my straight though RC40 exhaust with this engine? Or do I require a CAT?
Many thanks,
Tom
I now have an A+ MG 1275, a Metro 1275, and a 998! The MG metro comes with all ancillaries electronic ignition, HiF44 cone filter etc etc, but is without a gearbox. However, the Leyland 1275 has a gearbox but no diff. The 998 has a diff, but the engine isnt in good health! So, I intend to use the box off the 1275 and the 998 diff - will the box mate to a A+ MG block? Also, will the diff suffice and take the power of the MG 1275, which I hear is 72bph @ 6000rpm as standard
The MG metro also has a high lift cam and was rolling roaded before it was removed from a Mini, due to gearbox problems. It has covered approximately 55,000 miles in total. However, the cam is unknown, but I was told that it idled smoothly and ran sweetly.
I'm wanting to spec the engine for acceleration more than top-end speed.
What sort of power output will I be looking at with an MG Metro 1275, electronic ignition, MG alloy inlet, HiF44 carb with K&N, Cooper freeflow exhaust, with straight through Rc40?
One other question: Can I legally use my straight though RC40 exhaust with this engine? Or do I require a CAT?
Many thanks,
Tom
Edited by Mini_Lund on Thursday 15th January 20:48
Mini_Lund said:
What sort of power output will I be looking at with an MG Metro 1275, electronic ignition, MG alloy inlet, HiF44 carb with K&N, Cooper freeflow exhaust, with straight through Rc40?
One other question: Can I legally use my straight though RC40 exhaust with this engine? Or do I require a CAT?
I don't see why you'd need to add a cat? And it's really not something you want to have on a Mini anyway.One other question: Can I legally use my straight though RC40 exhaust with this engine? Or do I require a CAT?
Depending on what the condition of the engine is like, and how well it's been set up, I guess you could expect 75-85bhp or so. Might not sound like loads, but it will likely be more than double what the 850 donk put out on a good day, and will drive light-years better
Gearboxes were never my bag though! So i'll let someone else advise you there
Although you may have problems with the diffless 1275 box if it doesn't include the diff case/casting.P,
PJR said:
I don't see why you'd need to add a cat? And it's really not something you want to have on a Mini anyway.
Depending on what the condition of the engine is like, and how well it's been set up, I guess you could expect 75-85bhp or so. Might not sound like loads, but it will likely be more than double what the 850 donk put out on a good day, and will drive light-years better
Gearboxes were never my bag though! So i'll let someone else advise you there Although you may have problems with the diffless 1275 box if it doesn't include the diff case/casting.
P,
Ah, silly question on my behalf! CAT's wernt introduced until the early 90's. Well thats good news. As for the gearbox, you're right, the 1275 has no diff or diff casing, but the 998 does - I intend to use that. Depending on what the condition of the engine is like, and how well it's been set up, I guess you could expect 75-85bhp or so. Might not sound like loads, but it will likely be more than double what the 850 donk put out on a good day, and will drive light-years better
Gearboxes were never my bag though! So i'll let someone else advise you there
Although you may have problems with the diffless 1275 box if it doesn't include the diff case/casting.P,
I essentially have 3 engines to make one unit. 4 if you include the 850 
Tom
Hey, I'm currently battling my dad for space in the garage, as his Mk111 is in there. 
I have just noticed that the box on the 1275, is an A+ Metro box. Therefore the transfer case will fit the MG block and the CWP's and drop gears will fit! Which I'm more than happy about. I was told that the cam was a high lift cam, but was'nt always hunting. The cam profile is still unknow to me - any easy way of finding out?
I have just noticed that the box on the 1275, is an A+ Metro box. Therefore the transfer case will fit the MG block and the CWP's and drop gears will fit!
Which I'm more than happy about. I was told that the cam was a high lift cam, but was'nt always hunting. The cam profile is still unknow to me - any easy way of finding out?
A rough guide to cam spec is to use a DTI and measure the maximum inlet valve lift. Set the rocker clearance to zero with the cam inlet lobe in the dwell position.Position the DTI onto the top of the valve and zero it. Rotate the engine and measure the valve lift at maximum lift. With standard ratio rockers, the lift of the Kent range is as follows:
256 - 0.320
266 - 0.320
276 - 0.360
286 - 0.380
296 - 0.400
310 - 0.420
BMC/BL cams are as follows:
731 - 0.320
544 - 0.387
649 - 0.394
I don't have the figures for Piper Cams or for the SW range.
However, measuring the lift will give you some idea of whether the cam you have is just slightly better than standard or quite hot.
For reference, a standard 850 has 0.285, an early 998 Cooper has 0.312 and a standard 1275 Cooper 'S' MK. 1 has 0.318 (that's a BMC 510 cam).
I hope all this helps.
Now, with regard to your wanting better acceleration, the solution is easy as there are so many final drive ratios available for the Mini. If you are on 12" wheels and still want a reasonable cruising speed, probably a 3.44 diff will be fine. That'll give you about 16 to 17 mph/1000rpm in top gear. For even better acceleration, go for the original 3.76 as fitted to the 850 and 998 Cooper (and the early Cooper 'S' with 10" wheels). The rule is that to trade speed for acceleration, go for a lower diff. It does cut your available cruising speed though.
Also remember, the hotter the engine, the more often it'll need to be rebuilt. Also, with a hot engine, the higher the diff ratio the more often the clutch will need changing. For example, if you had an engine with a 286 cam or hotter and a diff higher than 3.44 (say 3.1 or 2.9), you would probably need to change the clutch every 3000 miles if it is used for everyday driving, due to the need to constantly slip the clutch in traffic.
Sorry for a long post, but there is quite a lot of data here.
I hope it helps, rather than confuses.
Peter
256 - 0.320
266 - 0.320
276 - 0.360
286 - 0.380
296 - 0.400
310 - 0.420
BMC/BL cams are as follows:
731 - 0.320
544 - 0.387
649 - 0.394
I don't have the figures for Piper Cams or for the SW range.
However, measuring the lift will give you some idea of whether the cam you have is just slightly better than standard or quite hot.
For reference, a standard 850 has 0.285, an early 998 Cooper has 0.312 and a standard 1275 Cooper 'S' MK. 1 has 0.318 (that's a BMC 510 cam).
I hope all this helps.
Now, with regard to your wanting better acceleration, the solution is easy as there are so many final drive ratios available for the Mini. If you are on 12" wheels and still want a reasonable cruising speed, probably a 3.44 diff will be fine. That'll give you about 16 to 17 mph/1000rpm in top gear. For even better acceleration, go for the original 3.76 as fitted to the 850 and 998 Cooper (and the early Cooper 'S' with 10" wheels). The rule is that to trade speed for acceleration, go for a lower diff. It does cut your available cruising speed though.
Also remember, the hotter the engine, the more often it'll need to be rebuilt. Also, with a hot engine, the higher the diff ratio the more often the clutch will need changing. For example, if you had an engine with a 286 cam or hotter and a diff higher than 3.44 (say 3.1 or 2.9), you would probably need to change the clutch every 3000 miles if it is used for everyday driving, due to the need to constantly slip the clutch in traffic.
Sorry for a long post, but there is quite a lot of data here.
I hope it helps, rather than confuses.
Peter
I wont quote the post, but thank you very much Peter, your advice is always clear and definitive! 
Well, I haven't aquired any of the engines yet as I'm battling my dad for garage space. I'm losing! I hope I can persuade him somehow or another. I'm sick to my back teeth of the 850. I'd rather spend money on a larger bore unit for more gains and driveability.
Well, I haven't aquired any of the engines yet as I'm battling my dad for garage space. I'm losing! I hope I can persuade him somehow or another. I'm sick to my back teeth of the 850. I'd rather spend money on a larger bore unit for more gains and driveability.
revingtosh said:
Am i right in assuming that standard ratio rockers are 1.3:1?
Bearing that figure in mind, should i add 30% onto figures gained from removing the rockers and measuring Pushrod travel?
Mike
Yes, if measuting push rod lift that will indeed be 30% less than the valve opening figure with standard rockers.Bearing that figure in mind, should i add 30% onto figures gained from removing the rockers and measuring Pushrod travel?
Mike
minimadmotorman said:
Are those bronze valve guides I spy? If so it's possible that the cylinder head has had some modification in the past.
Good luck!
I doubt it, but I hope your right! I cannot for the life of me, get the cyldiner head off the MG, I have managed to undo all of the head bolts, but the head will not shift. I have hit it with a rubber mallet several times to no avail. I even resorted to the butane flame, but still to no avail. I have sprayed WD all around the outer edge of the head and block, but it just wont come free! Suggestions?Good luck!
Its difficult to do anything when the engines sitting on its crank! I don't fancy getting the box off the Metro just yet either!
There is no engine number, the only part numbers I can see are that on the block face and on the crank itself, if I can get the crank number, will it tell you guys anything?
Put the plugs back in and turn it over with a long bar on the crank pulley bolt. The compressions may, just may, free it off. If not, you will have to use brute force!
Once in bits, check the case hardening on the cam lobes. It it's at all pitted, get another cam. Hardening is better these days, but a few years ago it was very poor.
Once in bits, check the case hardening on the cam lobes. It it's at all pitted, get another cam. Hardening is better these days, but a few years ago it was very poor.
Cooperman said:
Put the plugs back in and turn it over with a long bar on the crank pulley bolt. The compressions may, just may, free it off. If not, you will have to use brute force!
Once in bits, check the case hardening on the cam lobes. It it's at all pitted, get another cam. Hardening is better these days, but a few years ago it was very poor.
Great idea, however, I'll have to tip the engine its side to do so! I spy bronze valve guides also Once in bits, check the case hardening on the cam lobes. It it's at all pitted, get another cam. Hardening is better these days, but a few years ago it was very poor.
Stuff like this never happens to me, so I'm made-up! Excuse the poor pic's;
minimadmotorman said:
Take the water pump off and give it a good whack from the underside with a wooden/rubber mallet.
Those deffo look like bronze valve guides to me. any chance of some more pics of the inlet/exhaust ports on the cylinder head. might give a clue to if its been ported.
The head hasnt been ported I don't think, as the castings are still visible on the inlets and the exhaust ports are tiny. I'll get the water pump off asap - I used a scissor jack to pry the head from the block, but to remove the head it must come off flat and not as an angle. It does wiggle about abit, but not enough to get and lift off. Im aching all over, thats me done for today! Those deffo look like bronze valve guides to me. any chance of some more pics of the inlet/exhaust ports on the cylinder head. might give a clue to if its been ported.
Gassing Station | Classic Minis | Top of Page | What's New | My Stuff