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cylinder heads
Posted: Wed Sep 14, 2011 6:52 pm
by cadetchris
whilst discovering i had fudged the engine on the car today, i dug out my "spare" cylinder head and thought it might fit.
BUT, it has 12G940 stamped on it and 11 bolt holes instead of the 9 on the cylinder head that came off the car.
having done a bit or a trawl, a 12G940 is apparently quite a bonny head, but can i use it on my standard 1098 just using 9 bolt holes instead of the full 11 as drilled in the head???
Re: cylinder heads
Posted: Wed Sep 14, 2011 7:02 pm
by chrisryder
yes you can, just read up on other threads about fitting the 1275 head on a 1098 block.
you must have sufficient clearance for the exhaust valves.
Re: cylinder heads
Posted: Wed Sep 14, 2011 7:17 pm
by bmcecosse
If it has the 11 holes it MAY be a 'big valve ' head, although it's not unknown for folks to 'upgrade' standard heads by drilling the extra holes.. Measure the inlet valve heads - if 35.5mm they are indeed the big valves - and so really TOO big for a 1098. Good news is - it's an excellent head for a 1275 engine - and worth ~£100 assuming it' sin decent condition. You really want a standard size head - with 33 mm inlet valves. And yes - you need 320 thou clearance from valve head to cylinder head surface for the exhaust valves. If not 320 - you must sink the valves into the head until you DO have 320 thou.
Re: cylinder heads
Posted: Wed Sep 14, 2011 7:45 pm
by cadetchris
had a measure of the inlet valve faces and they are exactly 35.5mm, so as Roy says, too big for a standard 1098.
oh well, nice try. i thought i had a little gem of a head.
Re: cylinder heads
Posted: Wed Sep 14, 2011 8:24 pm
by bmcecosse
You have - it will sell nicely - much wanted for 1275 engine upgrade. Describe it as a 'Cooper S ' head and buyers will flock to it...
Re: cylinder heads
Posted: Wed Sep 14, 2011 8:25 pm
by linearaudio
cadetchris wrote:had a measure of the inlet valve faces and they are exactly 35.5mm, so as Roy says, too big for a standard 1098.
oh well, nice try. i thought i had a little gem of a head.
??? You HAVE got a nice gem of a head!! Worth a mint on E-bay! Hype it up (11 stud, big valve performance head...) and you will get enough for it to buy 2 standard 940 heads!
OOH YES... Add "Cooper" And you will mint it

Re: cylinder heads
Posted: Thu Sep 15, 2011 6:27 am
by Declan_Burns
cadetchris wrote:had a measure of the inlet valve faces and they are exactly 35.5mm, so as Roy says, too big for a standard 1098.
oh well, nice try. i thought i had a little gem of a head.
I have that head on mine and it runs like a dream,
Regards
Declan
Re: cylinder heads
Posted: Thu Sep 15, 2011 10:21 am
by cadetchris
ahh, so it could work.
hows the fuel consumption?
Re: cylinder heads
Posted: Thu Sep 15, 2011 10:18 pm
by Declan_Burns
Never measured it-it never concerned me but apperars very economical.
Regards
Declan
Re: cylinder heads
Posted: Fri Sep 23, 2011 6:31 pm
by bmcecosse
Of course it 'will work' - but that big valve head is better suited to a 1275 engine. But a 1098 will never flow enough air to warrant the larger inlet valves. It's up to you of course - but I suggest either keeping it for a better engine - or flogging it mercilessly on ebay - it will pay for a 'new' engine for you......