??break down of a big valve head build??

[turbojolt]

So whats involved step by step...i would have thourght its fairly more involved then just putting larger valves in with no mods but what do i know lol

[mowgli]

big valves, new seats. (professional job)
some porting work to smooth everything out (possibly diy)
new cam to make the most of it
better manifold/exhaust
possibly a bigger carb to make the best of it...

then more use of the rh pedal

[jimbob-mcgrew]

is this for your 12ST head TJ ?

as people say the 12ST has larger valves than the 12NV and 13S.

ive never managed to find out what size tho.

if the information in the past i got is right, the c14se valves share the same 104.6mm x 7mm dimensions, with bigger 38mm and 31mm heads.

but like mowgli says, youll need to get the seats professionally cut larger to fit

[mowgli]

the 12st head has the same valves as the 13s head. it is pretty much identical in every other respect too.

TJ, unless you are planning some decent compression ratio rise & a big cam, the big valve head might not be a good waste of your money.

remember, the 12st has that crappy 4-1 exhaust.. you can fit one off all the other novas with bigger engines & they have much better 4-2-1 designs

[turbojolt]

Autovaux have the c14se valves for around 90 quid


any ideas how much the valve seats work would cost roughly?

[mowgli]

i've an old s/hand head e16se knocking around here. you can have the valves for £10 posted. i'll even clean them up on the wire wheel..

i dunno on the prices, you'll have to ask some local engine recon places. don't ask any tuners, cos 99% will simply get a price from their local recon place & quadruple it.

[jimbob-mcgrew]

i think the e16se valves are shorter mo, 101.1mm if this thing is right. but youll have to measure them to be certain.

id probably leave the head alone myself, as your 1.2 carb valves are the same size as the 1.4 carb (which was 20 hp more). so it should pair with your 1.4 bottom end fine.
plus if the head gets machined out, for larger valves, it might reduce the compression ratio a touch, which will steal a horse or 2.
it will prob cost loads, for not much gain.

mo's mention with the exhaust manifold/downpipe is worth doing.
ive got a feeling the spi systems are different tho, with a triangular bolted mating connection, instead of U-clamps, so unless you have a welder, you might have to replace the entire system, bar the back box.
has yours got a cat after the downpipe too ? bosal exhausts says the 1.4 spi does. should ditch that too, to free up some flow.

[turbojolt]

Might just chuck a 14s or 1600 head on it with half a inch skimmed off it lol

No cat on it...looking at a tublar manifold at some point

[jimbob-mcgrew]

there better flowing heads, but youll loose your compression power with a 1.4 head. it will be less than a standard 14se on your NZ block, and if you skim a 1.6 too far, you might get valve contact.

they have different inlet ports too, so youll have to change the the inlet/carb as well, which is more monies.

keep what youve got i reckon. maybe add a mild cam, and get the carb properly setup/jetted, and it should be around 90 bhp

[mowgli]

keep what youve got i reckon. maybe add a mild cam, and get the carb properly setup/jetted, and it should be around 90 bhp
my first nova with the 1200+1300=1400 engine had about that power with a std 1300 cam & a std 1200 inlet & carb, but with the 1300 4-2-1 exhaust.
but what it did have was tons of low end torque. it pulled from 15-115 mph in top... (road trip to dusseldorf) and i'd checked the speedo calibration at 90mph.....not saying how or where....

[turbojolt]

it will end up running a kent ast2 cam but I want to use it first and get it on the rollers aswell, so I can get a idea of what the cam has done across the range.