(re)building a 1275 head

[amgrave]

That Cooper head (998cc) @ 28.3 cc seems a bit high, what was the reason for it do you think? Surly not to get away with using lower octane fuel

[philthehill]

The 998cc Cooper engine had a raised piston crown in the shape of a 'D' as part of the cast/forged top surface of the piston.
The 'D' helped bring back the compression ratio to 9 : 1.

Sadly no longer available except S/H.

I had them fitted in my 948cc Minor engine modified to 998cc with a modified 12G295 head.

http://www.preloved.co.uk/adverts/show/ ... stons.html

http://www.ebay.co.uk/itm/MINI-998-COOP ... Sw3mpXFUEq

Phil

[liammonty]

The 998cc Cooper engine had a raised piston crown in the shape of a 'D' as part of the cast/forged top surface of the piston.
The 'D' helped bring back the compression ratio to 9 : 1.

Sadly no longer available except S/H.

I had them fitted in my 948cc Minor engine modified to 998cc with a modified 12G295 head.

http://www.preloved.co.uk/adverts/show/ ... stons.html

http://www.ebay.co.uk/itm/MINI-998-COOP ... Sw3mpXFUEq

Phil

Flat-top pistons are the closest you can get to them now That's what I had to use in my 1030cc with a 12G295 head (I got some Nural ones). You can still get decent compression with these without skimming a huge amount off the head, fortunately.

[oliver90owner]

I stand corrected. Presumably there is more dish on the piston in the 1275 engine? And less on a 948? I think the only A series engine I have ever had the head off is our mini clubman auto when it got cooked. Fords were much simpler - 1650, GT cam, skimmed and gas flowed head, along with a pair of DCOE40 carbs went well enough.

RAB

[amgrave]

RAB
Ford tended to have the combustion chamber in the piston and flat faced heads where A Series engines have the chamber in the head.

[minijojo]

just to complete the confusion, this is the other head
[frame][/frame]
[frame][/frame]

it has to be cleaned first for final inspection. Comes from a running 998 Mini
looks good at the first sight

[philthehill]

The 12G295 head is the one to use on a small bore block and fits without any modification.
If not already skimmed would benefit from a 60 thou skim.
Phil

[bmcecosse]

It's the very best head for your engine -but it WILL need to be skimmed by that 60 thou. Measure the thickness of the head -as standard they are 2.750 " thick. A better cam (ex 1098 engine would be fine) would make it even better. Without skimming the compression ratio will be very low. Or of course - sell it - they fetch good money (if not cracked). Inlet valves for it are expensive so take good care of them. It uses the standard 948/1098 exhaust valves.

[oliver90owner]

Amgrave,

PM sent. A bit off topic for Minors.

RAB

[oliver90owner]

Tried to send again.

Sorry for these last two posts on this thread, but first PM did not arrive.

[minijojo]

thanks for telling me i did something right, by accident

measure the thickness.....

[frame][/frame]

i see its 7,03 cm, but i´m not able to read the inches...

2,750 inch should be 6,985 cm this plus a little bit of dirt..... seems it has standard thickness
0,060 inch means 0,1524 cm
after skimming should be 2,750 - 0,060 = 2,690 inch means 6,8326 cm after cleaning and skimming

[bmcecosse]

Looks like 2.750 " to me - why could you not 'read' it? So it's not been skimmed - and will need to be skimmed 60 thou to get any worthwhile result on a 948. Shouldn't be expansive - will ensure it is nice and flat, and a worthwhile performance upgrade.

[minijojo]

thanks for your info,
the reason i ´m not able to read the inches from the caliper gauge is, i only used metric until now. Seems i have to learn how to use the vernier scale when reading inches. Or i use my digital caliper which can be switched to displaying inches.
I will clean it the next day and look for a engine shop who are able to do the necessary works.
One guy told me that most of the engine shops are not able to process casting iron heads because they changed their machines to process alloy heads.
But i will hear what they say and will post here

[bmcecosse]

It can simply be spun in a lathe and skimmed that way....that's how A C Dodd (search Facebook for video) does his heads and they have a great reputation.