cylinder heads

[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???

[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.

[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.

[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.

[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...

[linearaudio]

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

[Declan_Burns]

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

[cadetchris]

ahh, so it could work.

hows the fuel consumption?

[Declan_Burns]

Never measured it-it never concerned me but apperars very economical.
Regards
Declan

[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......