Cracked 12940 head - repairable?
Turbo Mini Forums

Hello,

some advice needed, please!

25 years ago, I took a 12G940 head out of an original MINI INNOCENTI COOPER 1300. Head has valves with inlet 35,6mm and outlet 29,3mm (normal sizes in Innocenti 1300 heads).
There is seeing a crack between the inlet and outlet valve - there is normally not much distance("meat") between them. It's the cylinder next to the "water-hose" - is it called the 1. cylinder?
Of course, built in 1974, the head is not for unleaded use.

Is such a crack repairable?
And afterwards reliable?
The valve seats must be changed for unleaded ones?

Is a repair cost effective for such a head?

(Vegard repaired a cracked one years ago - it seemed to work)

What has to be paid for such a repair, done by a person with the
"right abilities and skills"?
(In germany, especially here in Bavaria near Nürnberg, I know no one specialized in classic MINI. I think, to prepare MINI heads in the right way, a "work shop" should better have MINI knowledge, too.)

Or is it a better way, to look for another head in good condition?
I think, most factory (1,3l GB) heads have the 33/29 inlet/outlets?
(But i would like to get this INNO head to "drive" again)

Had any A-engine factory heads, produced in GB after 1975 (BMC, Rover) inlets and outlets with 35,6 and 29,3 mm valves?
May be the engines in the MG Metro's?

Thank you very much for reading and your replies

Fritz

PS: please excuse the choice of words, mistakes and grammar -
it's only "my bloody school english" - decades ago.
I enjoy reading in this special forum since many months as
a guest - and sorry, I do have no turboed Mini.

Sorry, mistake in the topic - it's a 12G940 head.
Forget to type the "G"
May be, the topic can be corrected

Perhaps fitting Unleaded seats will cure this. BENROSS is your man on this topic.

By the way you can correct the topic by editing the 1st post. At the top you can change the thread title.

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hi frits,
yours head is SCRAP! in short

fitting unleaded insets with this head will not be reliable as soon as the head heats up the insert will fail and drop out killing the engine

i will reply to your PM my friend

im sure somebody onhere could source an MG head...

cant they be what they callled cold stitched then the seats cut n fitted? i've heard of heads repaired but i dont know owt about it! i have a spare 295 head i suspect has a crack but i'm not sure? i was gonna ask the same question as fritz?

SKYLINES ARE LIKE CLITS, EVERY FLANGE SEEMS TO HAVE ONE: see this sticker on my silvia

the Search-section on this forum is blummin superb & simple to use, unlike some other forums, without the search-section & the help of this bunch of chaps on here i'll never be able to !!!Start the day with a 998cc turbo!!! :) i'm getting closer though!

Tom Fenton says: I have it all, make me an offer

its not worth risking on a hard working motor

if the crack is between the valves it is fully repairable with a new valve seat or two!

i have succesfully welded a crack between seats,

WWW.FORCE-RACING.CO.UK PLEASE CLICK HERE

carl would you risk it in one of your motors ?

I know my dad has welded cast parts on engines successfully. Generally down to the price of parts at the time when we were kids. Good old school arc welding.

hmmmm with regaurds to my head its for a spare 1098 i got for a quid on egay! the 295 i have is fully ported & polished & looks a work of art! sheer luck! but...... it neads unleaded seats & that may reveal that its got 1 or more cracks between the valves, its hard to see even with a magnifying glass

i take it i cant just get the seats cut out & use the MIG myself to weld it & grind with my dremal!!!! :/ then have the unleaded seats popped in, i'm only considering this amount off work as the head is so nicely worked!!!

hope i have'nt invaded too much fritz & my question helps you too

mr benross & fastcarl + others will steer us in the right direction

Edited by clubminiflip on 14th Mar, 2008.

SKYLINES ARE LIKE CLITS, EVERY FLANGE SEEMS TO HAVE ONE: see this sticker on my silvia

the Search-section on this forum is blummin superb & simple to use, unlike some other forums, without the search-section & the help of this bunch of chaps on here i'll never be able to !!!Start the day with a 998cc turbo!!! :) i'm getting closer though!

Tom Fenton says: I have it all, make me an offer

I would never weld it, 940s are so common. However, if you mount inserts, the crack might go away. You wont see this unless machining for seats and then having it magnafluxed.
If it's standard, I'd bin it...

a good frien of mine, Ian Jonson, bought a new Longman GT17, 37,4mm inlets, wafer thin between valves with undercut, but the best flowing head i'd ever had on the flow bench on the inlet side
he then proceeds to use it with notrous, which promptly cracked it on one of the cyls,after about 5 runs.
a nasty fooker too, far too big to ignore.
so we gave it a good blasting with the oxy torch untill stinking hot and stick welded it up,

cleaned it up , re cut seats, and robert is your mothers brother, 99.9% perfect,.

normally welding anything cast is a mega pain with poor success rate due to contraction, but seing as the area was thin , when the whole job cooled and contracted the welded area could stretch and not re crack,maybe luck, maybe not,

if its standard head bin it , but if its had 40hrs put into it , you would have nothing to loose,except a casting,

carl

WWW.FORCE-RACING.CO.UK PLEASE CLICK HERE

i have a 12G940 head, :)

Drives
-Ford S-max Mk2 Ecoboost
-Rover 100 VVC #2 - track project

Searching is all you need on TurboMinis

normally the welded part is harder than the standard area so will be ok.

as carl said it will need heating to near red hot then welded, then you can get the inserts fitted. should be ok.

always looking for them bigger bunches of bannanas

Never thought of gas welding it. Good call Carl. :)
Mig is out of the question clubminiflip. With arc its easlier getting different rods.

Edited by Jason G on 15th Mar, 2008.

cheers from me chaps the spare 295 head i have has had many hours of work on it! looks really good, ports are mahooooossssiiiivvvee for a 295 & the chambers are so nicely done, its shame if it cant be repaired! if.........its cracked!

i have an oxy setup & no arc gear but i dont think i'd attempt it myself! i'll clean it up & seee what the machine shop says, anyone recommended to to this in the midlands,

SKYLINES ARE LIKE CLITS, EVERY FLANGE SEEMS TO HAVE ONE: see this sticker on my silvia

the Search-section on this forum is blummin superb & simple to use, unlike some other forums, without the search-section & the help of this bunch of chaps on here i'll never be able to !!!Start the day with a 998cc turbo!!! :) i'm getting closer though!

Tom Fenton says: I have it all, make me an offer

Had an S head successfully welded with big valves. But that was in the leaded days!

On 5th Sep, 2011 Vegard said:
I stand corrected. You should know