mk1-forum.net

What is the difference between an Innocenti 1300 head an an Cooper s mk III head?

same head as 1300gt, 12G940 flat top 11 bolt, 36/29 valves both

fred1380 wrote:same head as 1300gt, 12G940 flat top 11 bolt, 36/29 valves both

AAAAARRRGGGHHHHHH! Metric! (No offence, fred1380!)

The inlets are nominally 1&13/32", 1.40625", however they are normally quoted
as being about 5 thou down at 1.401/1.402". Translated into metric, this is 35.6mm.

The exhausts are 1&5/32", 1.15625" or 29.4mm.

The earlier 'S' heads had 1&7/32", 1.21875" which is pretty close to 31mm.

There is a lot of confusion these days with valves being sold as metric sizes when
they are actually imperial. A while back I bought some "37mm" inlets from MiniSport
and when I measured them, they were:
1&7/16", 1.4375"
rounded up to 1.44"
converted to metric, 36.6
rounded up to 37mm.

Naturally I was a bit miffed when I found that they were the same size as the valves
that I was intending to replace...

I sent them back saying that they were incorrectly described, afterall, you would not
put 73.5mm pistons in a block bored 74mm would you? And 74mm pistons would not
fit down a bore of 73.5mm, in engineering, half a milli-meter is a really big amount.

Clearly MiniSport didn't appreciate my logic because the last time I checked, they
were still listing the same valves as 37mm when clearly they are not...

thats cause they measure everyfin with a black pudding or a meat pie

im not bitter

ianh1968, I'm will ya on that.

I avoid as far as I can quoting any metric sizes regarding anything to do with Minis. I feel that these days, people are starting to think they are a metric car, but as you have so well put it, they are imperial and I for one would prefer that measurements, where applicable, are giving in their true imperial sizing rather than a metric close enough (is rough enough).

And half-a-milli-metre is the next size up over-bore! (0.5 mm roughly = 0.020")

I find for machining in general, working in thousands (or tens of thousands) so much easier than 0.01's and many machinists agree, even some of the new skool ones, but I guess that comes down to a yellow one being better than an orange one eh?

As best as I can remember, the only metric stuff from the factory that these cars had was the spark plug threads and the speedo cable fittings.

Spider wrote:As best as I can remember, the only metric stuff from the factory that these cars had was the spark plug threads and the speedo cable fittings.

There are a few more...

The screws that hold the bonnet release catch on are
M6 on my car, and aren't the screws for the later type
rad cowel on M6 as well?

Years ago I had a Mini Special 1100, (Belgium?).
The bonnet hinge "captives" were also M6.

I think that some of the bearing diameters in the gearbox
may be "French" as well?

Apparently Maplin sell that "graph-paper vero-board"
stuff for electronics and the hole pitch is "2.54mm".

ianh1968 wrote:

Spider wrote:As best as I can remember, the only metric stuff from the factory that these cars had was the spark plug threads and the speedo cable fittings.

There are a few more...

The screws that hold the bonnet release catch on are
M6 on my car, and aren't the screws for the later type
rad cowel on M6 as well?

Years ago I had a Mini Special 1100, (Belgium?).
The bonnet hinge "captives" were also M6.

I think that some of the bearing diameters in the gearbox
may be "French" as well?

Apparently Maplin sell that "graph-paper vero-board"
stuff for electronics and the hole pitch is "2.54mm".

Ha, sorry, I'm in Aust so I don't really know the UK cars that intimately. Our bonnet hinges have 1/4" UNF as are the bonnet catches, but the few models that did have internal releases were 10-32.

You may well be right on the gearbox bearings, especially in the later boxes, but in the catalogues (here at least) they are listed with imperial numbers, just super odd-ball, and while on bearings, for a very long time now I was puzzled by the OD of the front wheel bearings which were also odd-ball, until about 2 months ago when I picked up the very-nears and they were set to mm's,

Yeah, there are some connectors that have similar metric sizes

and what's the go with the Lucas Bullet Connectors? I don't think I've measured them but I think they are odd-ball - both imperial and metric - are they not?

But, what's all this got to do with MKIII Cylinder Heads? Where am I and when was it? Where have all the dingoes gone?

Some of the shafts / bearing in 3 syncro box,s are metric

Work that one out

I believe that the mk3 s head was stamped with 12g 1805 in small .
I don't found this stamped on 11 hole inno head's.
It might be that the inno head's are mould like the mk3 s head,but without the aditional numbers stamped on because 12g1805 belongs to the mk3 s?

Thats right , 12g 1805 stamped near the thermostat housing , theres also a letter K stamped on the 4 heads i have on the shelf and the head on my car - whatever that means i have no idea

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