1.2spi to 1.3 carb

[Muttly]

Hey all. I'm running a 1.2spi at the moment and a friend has the bottom end or a 1.3sr. First is i worth doing. I'd be thinking I'd be gettin close on about twice the power, would this be about right? From what I understand that would fit straight into my car with my head. Is this right? As for the spi I'd say I'll ditch it for a set of twin 40's. Any advice would be great. Anyone ever done this? What parts do I need? I'm guessing the bottom end anyway, a set of twin 40's and the inlet manifold. What about my fuel tank. Will it be alright or will I have to change it. Fuel pump? Throttle cable? anything else?
If I do go ahead with it it'll be done as cheap as possible cauz they car won't be on the road for much longer. I should be buying something new towards the end of the summer.
Cheers.

[Aragorn]

fitting just the bottom end will give u a 8% increase in power

fit the bottom end and follow my 1.2i tuning guide and u should be looking at 60-70bhp

if your gonna fit twin40's then u'd really want a 1.2 carb head as they are much better

[Muttly]

I thought all the 1.2 heads were the same.

[Snowface]

spi has restictive square-ports, sam as 1.4sr and 1.4spi.

1.2 and 1.3 has better cathedral shaped ports.

[Muttly]

For the amount it'd cost me I think I'll just wait till then new car. Its not really a great inprovement. Thanks anyway.