19 replies to this topic

[Clubby1275GT]

ive always wanted more power from the motor, everyone knows the first step is stage 1, done that.
next is either displacement or cam & head, or all three

Now i think my engine has done about 75k, will putting a cam in it that revs to 7000rpm just blow the thing up? it revs to 5800 tops now and surely revving it to 7k will not do it any good??

its quite a strong engine, never really had any probs except ur normal water pump and 1 head gasket change.

im seriously thinking of head and cam matched to see what improvement it may have over the 73bhp i have now.

but i cant help but think it will just go pop?

can someone explain to me that it wont or the contributing factors to having a head and cam, obviously u get more power and torque but what are the downsides?

Cheers

Daz

[Bungle]

if you going to strip down the engine to put a cam in then you might as well go for a rebuild

[Clubby1275GT]

what exactly does that consist of? big and litte ends etc?

[Jammy]

It shouldn't blow it up, but reving that high will increase wear rates. You also need to make sure all parts of your engine are capable reving that high, things like your crank and rockers may need to be uprated/hardened.

The other thing to look at is what you expect to your power and torque to be once you've carried out the modifications and whether your clutch and differential will be able to take the torque. You may need to uprate these as well.

Once you get to this point its start becoming expensive!

[Leonard]

go for a torquey cam and you shouldnt need to rev that high. you will need a centre main strap if you are revving that high.

[Cloverleaf]

I wouldnt rev a standard bottom end that high, chances are it wont be beneficial unless you have breathing mods and a cylinder head to compliment it.

Like said go for a milder cam

[Clubby1275GT]

can u give me an idea of what to go for then? my stage 1 1275 is 73bhp with about 78lbs torque, not bothered about figures, just want it to reliable with a little more poke, figured cam and head and leave it at that since i dont have thousands to spend, i no a chap who can do me an engine rebuild cheap, he builds autograss engines so i no it will be good.
his son won the class 2 nationals in a 1.1 uno thats over 110bhp!

anyhow, a stage 3 head and what cam would do? maybe a crank regrind?

[miniboo]

well why not change the head but leave the cam until you need to take the engine out.

I know i may bget slated for this but what about fitting some "different" ratio rockers as this is apparently like going up a stage in cam terms. Should work well as you already have a mg metro cam

[supermotolee]

yeah i'd speak to morspeed of swiftune about a head and rockers if i were in your shoes then if it does go bang for any reason you already have good compnents to build the bottom end too...

[Clubby1275GT]

i remember that rocker post that was like 40 pages long! i still havent come to the conclusion whether i want them or not, although i was at a rolling road where i saw the before and after power figures, pretty impressive.

ok i may just get a head and leave the cam, but theres two types of rockers ent there, rockers and full roller rockers??

obviously it would be the 1.5 ratio but do u need to change anything else while ur at it to prevent excessive wear, i no we've been over this before but it all in one reply would prob make more sense to me!

[miniboo]

i would go for roller tip rockers as they are a third of the price.

may need to change the springs but speak to whoever you get the head from and they will be able to recommend what is best to do.

Me personally i am putting 1.5 roller tips on. i am not changing anything else but i am just driving the engine till something breaks and then its 1380 time.

[Bungle]

my 1275 cc cooper i have gone for a stage 1 kit modded head and 1.5 roller tip rockers and the standard cam

i have got 85 bhp at the fly wheel

after this its a engine out job for better cam and more cc's

[TimS]

A head would be my first port of call (no pun intended) try it like this for a while, you might be happy with it, if not then you can always decide to go for a cam such as the Swiftune SW5 its a very well know and torquey cam.

As for the rockers, I would leave them. I have tried both with and without them and personally I found that I lost low down torque for gain at top end. Though this was with a Morspeed phase 2 cam and modified head.

[Cloverleaf]

IMHO the full roller rockers are worth the extra money, they are better for your engine too....and as chances have it I have some in very good condition for sale

[Clubby1275GT]

how much u asking for them?