12NV - square or cathedral inlet

[paul080803]

As title.

Would a 12NV happily take a 1300 inlet, 32/34DTML carb, 1.6 cam (1.4SR cam better?) and upgraded exhaust?

A mate is looking to gain 15-20 bhp from his 12NV, without changing the engine and straight forward bolt on mods.

[Stuart]

the 1.6 cam is unlikely to have the fuel pump lobe, so would need an electric carb pump + pressure reg etc.
Velos tested the 1300 cam in a 1200 and it made 5bhp... A respectable gain there.

[paul080803]

the 1.6 cam is unlikely to have the fuel pump lobe, so would need an electric carb pump + pressure reg etc.
Velos tested the 1300 cam in a 1200 and it made 5bhp... A respectable gain there.

Thanks, so stick a 1300 cam in, or what about the whole 1300 head onto the 12NV block?

[Stuart]

NV should be the "same" head as a 1300, as in it'll have cathedral ports.

NZ will be SPI and square/rubbish/1400 ports :D

[paul080803]

NV should be the "same" head as a 1300, as in it'll have cathedral ports.

NZ will be SPI and square/rubbish/1400 ports :D

It is definitely a NV. So no gain from fitting the 1300 head, just the cam.

Cheers

[mowgli]

Please just fit a 1400 bottom end. The insurance will be less than with all those mods, and the cost will be tiny compared to them, the increase in power and torque will be way better

[turbojolt]

Or fit a 1400 bottom end with a 12nv head. That way it's stamped saying 1.2

[turbojolt]

I've had the 1300sr head and 12nv head side by side and couldn't see any difference between the two, so a head swap imo would be pointless.

The Sr inlet does fit the head as they are identical

1300 cam should produce gains, along as it isn't worn massively 20+ years old cam will be worn to some extent

[paul080803]

I agree, however he will not entertain an engine/block change. I have tried countless times but he will not do it.

He has bought a brand new 1300 cam, an astra mk1 1300 inlet and carb and is currently deciding which exhaust system to order.

[turbojolt]

It's fair enough not like anything he is doing right now can't be used on a 1400 bottom end later

[mowgli]

An astra mk1 1300 carb is a waste of money on a 1.2. It's underused on the 1300

[turbojolt]

He might want the autochoke

[Stuart]

He might want the autochoke

He might also want Chlamydia, but it's not advisable

[Royston]

The combustion chamber on the 1.3 head is larger than the 1.2, so lowers the Compression ratio.................negative result

[turbojolt]

He might also want Chlamydia, but it's not advisable

Not everyone likes pulling on nobs like you

[paul080803]

An astra mk1 1300 carb is a waste of money on a 1.2. It's underused on the 1300

Would a 2e3 be a better option then?

[mowgli]

The 1.2 simply doesn't need it unless it's getting some serious head work & a load more compression.