a12 performance suggestions

[chris23]

Hi guys. Great site. I am restoring my 1979 120y which has the 1171 cc motor . Im wanting to keep the a 12 in it. Whats the best mods to do to safely get another 30 to 40 bhp out of it .

[Datto_610]

Twin side draught carbs, extractors, lumpy cam to name a few? Shouldn't be hard to squeeze a few more ponies out of the A12 plenty of people here have.

[chris23]

Cheerz thank u for that. I want to stick with the a 12 as i really rate them as a great motor . Any advice is appreciated as im more use to modern turbos an 6 cylinder motors.

[Kitch]

Here is my 2 cents:


INDUCTION:
Standard carb is limited for HP increase, so usual upgrade is to update this,
ie 32/36 webber downdraft carb & manifold or twin dellorto sidedrafts or twin SU's
Carbs should be overhauled and jetted to suit engine.
dellortos you probably want to run 28mm chokes for a worked A12
Other options are obviously EFI / or turbo or supercharger (but I prefer N/A!)

EXHAUST:
Flows & free flow 2" exhuast

HEAD:
Strip & recut valve seats , machine valves etc
new stem seals
Double valve springs
Port & polish
Upgrade rocker gear to solid bushed spacers
plane/surface head in conjunction with combustion chamber size & block deck height for desired static compression ration. target perhaps 11.5:1 and run on 98?


ENGINE:
Rebore, oversize pistons 20' or 40'
dip the block, machine for new bearings
new timing chain & custom cam grind to desired performance
new bearings, gaskets etc throughout
Crank work, ie grind, knife edge balance etc
service oil pump
baffle sump
Lightened flywheel
machine & balance rotating assembly

ELECTRICAL
Decent plugs & leads
Electronic ignition
ensure battery & alternator performing well


All depends how far you want to go, you can spend easily 5-7K doing the above professionally.
however an A series screamer is worth it! 69Hp could easily change to 100-110 HP with above mods

It might be worth keeping an eye out for an ex minisprint A12, as these tend to be well spec'd and can be picked up for around 2-3K. you could then just freshen up and retune / re jet for pump gas from methanol.


Thats all I can think of on a Sunday morning......

[chris23]

Well id say that's a dam good effort for a sunday. An brilliant that has opened my brain. Il happily use this advice as its briliant. Much appreciated .

[grant76]

to get an extra 30-40 hrsepower out of an a12, a small turbo would be another option as kitch said. To go from 69 horsepower to 100/110 with cam/carbs/rebore/exhaust is definately one way to go (1200 sss only had cam, twin 40mm carbs and extractors and got around 90 horsepower). There's definately examples of people using standard, non-rebuillt a12's with turbo's to improve performance significantly (in saying that i would prefer the oldschool carbs myself!!) just another option to consider??

[Loganw]

How much you wanting to spend mate? How mechanicaly minded are you?
I was hoping to put together a list of things to do on a thread.
What ever you do think of it a bit like this
HP is not everything.
Budget is a key driver followed by what you want it for.
You want to stick with an A12, N/A you want to build a hi reving screamer
Or turbo/SC will give you good power at a cost.
Standard A12 are a strong little engine and a great start for both making power and learning about the ins and outs of engine building.

Sorry its a little late and my heads not the best so I'll post but re look at this tomorrow.
But as usual Kitch is on the money

[chris23]

Thanks grant and logan. Kitch has presented a effective resolution. I would like to achieve knowledge for the best possible combination. Since this datsun is my long term project I dont want to be shy with money as im intending to hold on to it. I have some mechanical knowledge, but my friend is a long time raceway mechnic. So im trying to get together options to discuss. And yes HP is not everything, I want to maintain reliability along with some power, like we all like.

[Bartman]

Bang for buck I don't reckon you can go past a simple drawthrough turbo set up.
A simple J pipe set up with a turbo like a t25, and an 1&3/4 SU. Slap on an A15 head, and a few other bits and bobs.
I've always to build a turbo A series. But the opportunity has never presented itself.

[b110sss]

I absolutely agree with Bart- hp for dollars you simply cannot beat a simple turbo setup and I can assure you that you will never stop smiling once the boost kicks in and you are grabbing gears...
If you want some serious inspiration have a look on datsun1200.com and check out Sikynes 1200 Improved Production coupe
Cheers
Dave