12.tuning

[Anonymous]

Whats the best route for tuning the mk1 1.2?-Ive heard the 1.3SR cam fits in and works wonders,anyone know how much of the 1.3 engine is compatable as they appear to be basically the same engine?-if this is true,what parts do I need to convert my 1.2 lump into an SR engine(if it is possible) as for 0.1 of a litre theres quite a bit of difference in hp. would a 1.3 top end and cam from an astra perform ok?

[Anonymous]

The 1.2 has a larger bore than the 1.3, but a shorter stroke.
Fit a crank from a 1.3 into a 1.2, and you get a 1.4! (if this can be done?)

So, you can't turn a 1.2 into a 1.3 'cos you'd have to make the bore smaller!!!
Well you could, but it'd be different spec to the normal 1.3

The head is the same, as is the cam-housing, so you can fit a 1.3 cam onto a 1.2 engine.
I'm not sure what performance you'd get from this, but since the 1.3 cam has a higher lift (6mm on inlet and outlet), then it should improve things.
The 1.2 cam has lift of 5.1mm inlet and 5.5mm exhaust.

I don't know about the Astra head, as I don't know about it's spec, but I do know that the Astra 1.3 produces 75PS rather than 70PS of the Nova 1.3
5 more, so maybe it's got larger valves? Don't know, maybe just a different cam. The carb is the same, but it may have different jets?

[Anonymous]

keep the 1.2 head it is better than the 1.3 also a webber 32/34 would be a good upgrade

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[Anonymous]

so I should go for the cam,then a performance backbox,and eventually some webers,depending which come up cheap as I go along?

[Anonymous]

ste.....isn't the 1.2 head the same as the 1.3 head anyway? The spec is the same in the Haynes.

bob......you should be able to fit a full exhaust, not just the back box, but the 1.2 manifold is different to the 1.3, so unless you also got a performance manifold, you'd have to get one off of a 1.3 - the 1.3 manifold required the use of a longer, twin-down pipe, that goes right under the engine.
I'm sure this can be fitted onto the 1.2 since the head is the same.

Does anyone know why the Astra/Cavalier 1.3 had 75PS.....5 more then the Nova 1.3?
What is it about it's spec?

[Anonymous]

1.2 head is better flowed

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[Anonymous]

so 1.4 pistons will fit a 1.2?? what crank is best and what con rods are the best?? and what cam is the best. so i can raid a scrappies!! i have a 1.2 12nv engine!

I AM CORNHOILIO

[Anonymous]

12NV???? Sure it's not a 12NZ?

Bore of the 1.2 12ST = 77.8mm
Bore of the 1.2 C 12 NZ = 72.5mm
Bore of the 1.4 14 NV/ C 14 NZ and C 14 SE all = 77.6mm

[Anonymous]

I KNOW ITS A 12NV!!! its on the block and its in some books!!!! just haynes conveiniently forget about it!!!

BEng Hons Automotive Electronics Engineering :) worship my electronics skills :D

[Anonymous]

And to think, we put our trust in the Haynes!
What year(s) were that engine fitted?

What reg is your car?

BTW - BEng Mech Eng - worship my mechanical skills lol!

[Anonymous]

its H plate 1991. its only in the flairs!!!
mk2 with mk 1 bakes and other such shite

mech eng lol

BEng Hons Automotive Electronics Engineering :) worship my electronics skills :D

[Anonymous]

haynes are s.hite anyway. they only provide a "clue" how do stuff. the instructions for changing a clutch on a 5speed is in the CAV manual!!!

BEng Hons Automotive Electronics Engineering :) worship my electronics skills :D

[Anonymous]

lol.....what manual have you got? guessing the green one?

The old blue one is miles better, but is from 1986, so only covers the older models.
It's ok for my 87 Nova, as the spec didn't really change. I've got both manuals though, ready for my GSi!

[Anonymous]

I got the official vauxhall workshop manual,its done by haynes and is white with vauxhall and all that crap on it,I got lucky at a car booty while looking for star wars figures(okay,you lot are gonna call me sad twat now) I dont know if this haynes manual is any different tho :-/