Does such a post already exist that explains what origin/spec different motors an heads are?? Just bought a 1275 motor and box seperated (no head) motor is stamped 12yd/Ta/H15661... I have two 10y/Ta/H motors and the valves on these are bigger than the ones i found among the bits in the other cars. The valves i found are 1 inch diameter, the 10y ones are 1 1/16. The head has 12G202 on the casting.
does any of this mean anything to anyone??

ahh the 10y has a 66mm (roughly) bore 12y is 72 ish..
is the 10y which came from a morrie 1100 the same as the mini K??

don't know if this hel[ps, 12/yd/ta...
is a morris 1100s motor (1275cc) and
apparently has a good crank. comes with
a 12g940 head and cooper s rockers
(mine had cooper s rods as wel but don't know
if this is standard? well i think they are??)
mine is at russell engineering at the moment being niced up.
but i think he left the country i cant seem to get in
contact with him....

the motor had no head so i was wondering if i could use one of the 1100 ones. I can get a 12g940 bare head (crack tested) (cool xmas pressie for a 14yo girl LOL) but fitting it out will cost her another few hundred probably, and her money is going into other areas atm. I also have a 1000 motor , but from memory these are a different bore size also??

Small bore heads (850, 998, 1100) will not fit a 1275 block. You need a 1275 head - 12G940 or the pollution version, which I can't remember...

12Y/Ta/H engine number is indeed a Morris 1100S - which is actually a 1275. For some strange reason BMC bought out a 1275cc in a Morris 1100 shell and called it the 1100S. (Not to be confused with the Cooper S 1071cc - which are as rare as rocking horse poo)

10Y/Ta/H is regular standard Morris 1100 engine (1098c) with 12G202 head. Auto Morris 1100 has the big valve 12G295 and a different engine number. THis is the head I have on my van.

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Brett Nicholson
Greendale (near Ballan) VIC.
1971 Morris Mini Moke
1966 Austin Mini
1965 Morris Mini Traveller
1973 LR Series 3 88
2007 LR Freelander 2

Not all 12Y/TA/H blocks came with Cooper S rods only some. My does not have them but a Mate of mine got a 12YD/TA/H block and it had Cooper S Rods so it is possible that the D means a different style of internals.

Not to sure bout it tho.

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I've Got One
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What Is It



A Bloody Mini

1970 Mini K, 1380cc, 1.75 HIF SU, 30 70 Cam, 2" Zorts
1969 Mini K, Stock Standard and Orginal. (Slow as Hell)

any particular reason it wont work? it appears physicly similar water jacket holes slightly different.. with the smaller cylinder size wouldnt it be easy to take a bit of shoulder of the chamber? then plane... the valves seem back enough to avoid a collision.
am i missing something important??

interesting, always wondered if there was a difference??

Bore spacing is different, chamber volume is wrong and valves and ports are much smaller - basically you will lose a considerable amount of performance. You could probably make it work, but why bother going to all that effort? Get a s/h 12G940.

_________________
Brett Nicholson
Greendale (near Ballan) VIC.
1971 Morris Mini Moke
1966 Austin Mini
1965 Morris Mini Traveller
1973 LR Series 3 88
2007 LR Freelander 2

The 1275 head gasket (which must be used due to bore size) will not cover the big water hole below the thermostat on a small bore head, so even if you bolt it on it will leak.

re the 1275 engine #- my car has a 12YD/Ta/H motor, it had a small journal EN16 crank and S rods in it. (Got an S crank & rods in it now.. )
The ones with good cranks don't have S rods.. they have bigger (1.75") journals with the heavy 1100S rods. OK for a road motor, but for racing I'd get some A+ rods which are stronger and lighter.

<edit> you can lighten the 1100S rods, but using A+ ones saves you the aggro.

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

From the Morris 1100 workshop manual.

Engine Type Code
12 = Capacity of the engine
Y = Australian Manufacture
D = Variation to power unit 'D' = 4.1 final drive
Ta = Std. ratio remote centre change
H = High compression

From the Morris 1100 parts book
The change point for the conrods was between 12YD/Ta/H - 10487 and 12YD/Ta/H - 10488. So if it was built before the first number it has the cooper s rods (AEG520) and if it was built after the second number it will have 12G1506 rods.

thanks people much appreciated