7 replies to this topic

[thebullet]

Hi all, recieved a head which I purchased ebay a couple of weeks ago, I have cleaned it up and would like to get it restored at the Mini and metro centre.

I plan to fit it to my Mini Sprite 998. I understand this head can give about 6bhp difference to the stock head. Fitted to my sprite is a stage 1 kit, along with the 12g295 cooper head and a good compression ratio how much Bhp are we looking at?

Thanks
Matthew.

[majj2]

Hi all, recieved a head which I purchased ebay a couple of weeks ago, I have cleaned it up and would like to get it restored at the Mini and metro centre.

I plan to fit it to my Mini Sprite 998. I understand this head can give about 6bhp difference to the stock head. Fitted to my sprite is a stage 1 kit, along with the 12g295 cooper head and a good compression ratio how much Bhp are we looking at?

Thanks
Matthew.

Hi Matthew

Ive fitted this type of head to a couple my mini's and is on my current one. Ive fitted twin carbs to mine aswell. Dont know the exact power increase (Needs rolling road)but it does improve the power and torque if set up right.You need to get the head skimmed right to give you the correct comp ratio.

Regards
Matt

[thebullet]

Ah good, I just have a modded carb to increase air flow. I am planning to have 80 though taken off the head.

[Ethel]

998 Cooper was good for 55hp. It wouldn't be hard to better that with some porting and good compression. I got one to give about that at the wheels, with a cam.

Ah good, I just have a modded carb to increase air flow. I am planning to have 80 though taken off the head.

[level7]

Hi all, recieved a head which I purchased ebay a couple of weeks ago, I have cleaned it up and would like to get it restored at the Mini and metro centre.

I plan to fit it to my Mini Sprite 998. I understand this head can give about 6bhp difference to the stock head. Fitted to my sprite is a stage 1 kit, along with the 12g295 cooper head and a good compression ratio how much Bhp are we looking at?

Thanks
Matthew.

I just built a 998 using the same head casting (mine came off a wolesley 1100) the motor was standard bore just honed, 649 cam, lcb extractors and a hif38 on metro inlet with pod filter, before the engine swap the car would be in 3rd or even 2nd to get up hills and top speed it would do was 110km/h, after the swap and running in period the car would accelerate up the same hills in top gear and would still be accelerating pretty well at 120 km/h.
I did have to get 100 thou taken off the head though in order to get around 9-1 compression ratio (chambers went from I think 26cc down to 21cc)

[Cooperman]

When fitting a 12G295 head it is absolutely vital to measure what you have and do an accurate compression ratio calculation, then to machine the 295 head to suit.
As the 295 will be an old head you don't know if it's been machined before, but take care not to skim too much off or you can break into the oil gallery. Get a depth vernier and measure the depth of the oil way hole inside the head, then measure the total thickness of the head. The difference, less 0.050", is the absolute maximum you should skim as if you do skim that much you'll have only 0.050" left before you break through. I would rather use 0.060" as a minimum, but 0.050" is a figure I've seen quoted elsewhere.

[bmcecosse]

As Cooperman says - check first to see if the head has already been skimmed - all heads start off at 3.750" thick - any less - it has been skimmed by that amount. 100 thou is a LOT to take off these heads - the deck becomes very thin and it can be hard to get the head to hold a gasket - been there, done that! I suggest no more than 80 thou for safety. But - I have to say - a 12g940 is a MUCH better head and needs no skimming, and will give a lot more power. Just check you have 320 thou from face of exhaust valves to head surface - if not - sink the exhaust valves by whatever is needed to get that figure. Simples!

[thebullet]

Sorry to bring an old topic back up, Got my head checked out, only 10thou has been taken off, still another 120thou ish left before hitting the oil gallerys. Also found some Twin HS2 Carbs lying around the garage so I am going to fit them.

12g295
HS2 Twin Cabs
Stage 1 Kit

Sounds good to me !