940 head - what is the advantage

[d_harris]

Ok, so what actually is the advantage of a 940 head over a 295?

[Peetee]

Larger valves so better breathing at the top end. Although the book says that will reduce mid range torque (some wee folk have yous believe otherwise ). You don't need to skim it so that could save you £80 +/- but you will probably have to sink the valves so that could cost you £80+/-. If you have a 295 you can get a lot more ker-ching for it than a 240.
erm......

[bmcecosse]

It has MUCH bigger inlet and MUCH bigger exhausts - better chamber shapes and larger ports . Ideal on a 1098 - I swopped out a well modified 295 for a slightly worked (exhaust throats) 940 and the car was MUCH faster - and no loss of 'torque' - in fact it pulls better at all revs. If using a standard cam - it's very possible you don't need to sink the exhaust valves - measure and see ! You need 320thou clearance - an older 940 will likely have some valve recession -ideal !! Unfortunately prices have risen slightly - I wonder why ?

[d_harris]

I dont see anything there that improves on my 295 head then BMC. (no, its not exactly standard)

[bmcecosse]

Apart from the bigger valves/better porting and better chamber shape that is............
Honestly - I was amazed how much better my engine runs when I swapped out my much modified/skimmed 295 for the slightly modified 940. It's up to you - but I won't be swapping back to the 295!

[d_harris]

You dont know what valves I've got

[cadetchris]

would this 940 head be from a 948 engine or is it the casting or something?

[d_harris]

Its the casting number. 12g940 was fitted to 1275s and came in a big and a bigger valved flavour. (you cant tell which is which without looking at the valves mind)

the 12g295 was fitted to 1098 healy and mini coopers and is reckoned by Mr Vizard to be the best head for the small bore engines

[cadetchris]

ah right,

ill keep my eyes peeled for one of those

[bmcecosse]

It's the head from a 1275 engine. I know you have fitted larger valves to the 295, but unless you have moved the centres of the guides they are unlikely to be as big as the 940 - the point is, it's just not worth it when perfectly good 940 heads are ready made with the larger valves/better porting/better (shallower) chambers - and no need for skimming....... But having done it - you may as well use it - although if it was mine, I would flog it to a Mini owner for good money.....
Vizard just says it's the best of the small bore heads - not quite the same thing......
Way back 40 years ago I was running a Cooper S head (so even bigger valves!) on my 998 engine - and it went like stink. In the racing world - the S head conversion on 848 Mini engines was standard where regs didn't 'ban' it - Clive Trickey was the man who told us all how to do it in these days (long before Vizard) in his articles in Cars & Car Conversions......