Morning all.

I also own a Skyline gtx, but use the datsun1200 to work everyday, cause its economical and bloody reliable. But the take of power sucks,
So I'm thinking of using the SKyline to work more often, but this will cause a dent in my budget
I want more take off power, cause the datto does a lot of robot to robot driving

I have an a14 carbi on my datsun 1200.

I would like more power, so I would like to purchase the stock SU carbis and manifold from a 1200gx.

However, before I do so, I would just like to know a few things.

1. Is the SUs high maintenance and will it be possible to service them myself easily.
2. Is there parts{kits} for these carbis available,new.
3. How drastic will the fuel consumption be.
4. Is there anything that I can do, to improve the a14 carbi, for more perfomance.
5. Is the SU's a better option than the webers.

Please guys, any suggestions welcome.
I want performance and reliability as well.

Oh another thing,
Is it true, that a 1200 with these SUs can take on an newer model 1400 ute on take of.
If true, I want the SUs, but first, your opinions.

The stock dual carburetor setup for Datsuns uses Hitachi carburetors, not SUs.

> 1. Is the SUs high maintenance and will it be possible to service them myself easily.

No, not high maintainence. Yes, you can service them yourself, it is just as difficult as the downdraft carburetor

> Is it true, that a 1200 with these SUs can take on an newer model 1400 ute on take of.

I doubt they will improve "take off", but they should extend the torque curve upwards into high rpm territory.

> 2. Is there parts{kits} for these carbis available,new.

???

> 3. How drastic will the fuel consumption be.

It won't be as good if you'll be revving the A14 up more often. Otherwise, just as good (keep engine below 4,000 rpm).

> 4. Is there anything that I can do, to improve the a14 carbi, for more perfomance.

Not really.

> 5. Is the SU's a better option than the webers.

Depends on price. If they are the same price, a pair of side-draft webers an give more performance, the Hitachi side-drafts or SU-side drafts can give better fuel economy.

Thanks DD.

Tell me, from what donor cars does these 32/36 weber carbis com from, and besides these webers,
is there any others carbis that can fit on the stock a12 manifold with perhaps only an adapter base plate.{for better performance on take off}

These twin Hitachis you spoke about, are kinda hard to find in good working order around these parts.

Thanks again

Hi Reeves

I know we talked on the phone about these things, but I am going to write again the stuff I know. Basiccaly for others to comment on if they want to.

As you know I drive a 1200GX that came from the factory with hitachi flattop SU's.

1. I have manuals that I got on the internet on tuning these carbs. If you do get hold of hitachi SU's that are in good condition you can give me a ring and I will gladly mail them or fax them to you. Mine has'nt been retuned in about 3 to 4 years.
2. Sidedrafts I will not reccomend. I wanted to put them on myself but since then have decided to stick to my Su's.
Basically they are heavy on fuel consumption and need constant tuning. This is what I was told.
3. Power. Hitachi Su's give good power with good fuel economy. I must admid I have a GX head also that helps with a bit of more power than the stock 1200 cylinder head.
But I took on one night a 1400 utility.
To be precise a Nissan 1400 champ.
We dragged 3 traffic lights after each other.
Spaced about 300m apart.
I remember this because after the 3rd one my brakes started to fade away.
EVERY time I grabbed 3rd gear I started to pull a gap on him. 1st and second we were side by side. I revved to 6000rpm.
4. Parts. Nissan only sells the needle and seats now and the needle that lets fuel in and out. No other parts are available.
5. When looking at buying used SU's look at the butterfly for wear. I bought another pair and did not look at this. These butterflies are worn and I think are useless to me.
6. Personally I will also not put on a 32/36 as many complained on this site about jetting and flat spots. Rather put on a 34mm weber carb or MAYBE a single 40 sidedraft weber.
A single will be easier to tune and good on fuel.

Let me know if you need any other info.
You still have my number.

The Datsun 1200GX did NOT get it's higher performance from the twin Hitachi's

To assume that a single thing will make all the diference is pure folly.
Those really clever engineers at Datsun built a whole GX engine instead of just adding carbs to an existing one

The GX engine had more compression from it's flat top pistons
It had the twin carbs as already noted.
It had a well designed free flowing dual outlet exhaust manifold.
It had a better cam profile that was tailored to the engines new performance level
It had double valve springs to cope with the higher revs that it was capable of
It had a whole new cylinder head with larger, oval shaped inlet ports. This head also had a diferent bolt pattern to bolt the manifold on & the manifold will not fit the standard 1200 head.
Even the fuel pump was changed to provide slightly more fuel pressure.
The water inlet pipe on the block is diferent to accomodate the water hose from the inlet manifold.

Other than that, they are pretty much the same. From this it's obvious that the carbs are just a part of a well balanced package of components, & thats why the GX is so good.

You may be able to duplicate the GX pistons if Datsun 1000's were sold in SA. The 1000 used a flat top piston with a longish skirt. When the 1200 came along, with it's longer stroke, they shortened the skirt to prevent it hitting the crank, & they made a dish in the crown to maintain the compression ratio.

In Australia, Repco decided that they could cut costs by making pistons for both engines by using the shorter skirt 1200 blank They machined a flat top for the 1000, & a dish for 1200's
If one uses the "replacement" 1000 piston, you get a flat top piston for use in your 1200. If you have replacement piston makers in SA, then check to see if such a thing is available.

This is what i used in my wife's green 1000 two door. The pistons for both models of engine were the same price, so i got a modest boost in compression for FREE

By all means, get the GX inlet system, but get the rest of it as well.

Oops.
Dodgeman are right.

The GX engine did come with all those extra stuff as mentioned.
But Dodgeman I would like to know something.
Will he not get a bit better performance with the Su's and still have good fuel consumption?

A Nissan mechanic friend of mine said that SU's give better torque than the standard carb that the deluxe came out with.
The head will also help with torque because it gives better compresion and as far as I know higher Comp gives more torque.
I am trying to help Reeves with a cheap power upgrade without opening the engine.

1200GXman
If he has the standard head, then the GX manifold will not fit, & even if it did fit the head, the manifolds oval ports are bigger than the standard round ones, so it would be better to get an aftermarket twin SU manifold, & see if it is possible to get the whole carb setup from a Mini cooper, or MG sports car.
This would be a great time to switch to a set of extractors/ headers too.

Once the carbs are correctly tuned, the fuel consumption will be totally controlled by the drivers right foot.

Always remember this.
Power is made by burning fuel. You want more power, you burn more fuel. It really is that simple.

I managed to get over 50mpg from my engine one day when i drove strictly for economy, yet it delivered all the performance that i needed when i asked it to, & mine was a slightly improved 1200GX engine. [big bore] Thats better than 17.6 killer-metres per liter of fuel.

On a midnight run from Albury, in NSW, to Bendigo in Victoria one night, i averaged just over 71mph [114kph] for the 250 mile [400k] trip & averaged just over 42 mpg [14.8 k/l]
Is that good enough economy at cruising speed?

Thats what i loved about my car, good performance, or great economy, it was all up to me.

Dodgeman.
Yes, you are right the manifold will not fit onto his head.
But I saw yesterday at the suspention place where my suspention rubbers were replaced a A14 utility that they fitted a SU intake manifold and two SU's.
It is maybe possible it is a oval A14 head with the correct bolt pattern.
Do you know if the A15 cylinder head with oval ports have the correct bolt pattern for the SU intake manifold?

Reeves.
I think your best option would be for a single 40 sidedraft weber and extractors.
Your problem will be that you will have to fabricate your own intake manifold.
If my SU's gets worn out so that they are not usable anymore, I am going to fit a single sidedraft weber.

As has been mentioned on this site, many many times, the A14/15 heads have the oval ports & the correct bolt pattern.
There are really only two manifold bolt patterns. One for round ports, & the other for oval ports.

As has also been mentioned in this thread, they are NOT SU's,... they are Hitachi's.
If the throttle shafts become worn, any decent carb specialist worth the name can drill the carb body & fit bushes. They should also be able to replace the shaft, thereby restoring the carb to "as new" condition.

The A14/15 heads can be used on the 1200 block, but
A. Check the combustion chamber volume of the replacement head before using as a larger chamber means lower compression, &..

B. Modify the head so that the rockers get oil. This may mean grinding a small groove in the gasket face from the place where oil comes out of the block, across th the nearest head bolt hole.
Machining a groove would be best.

how do i check the butterflies and all that on SU's as i am buyin a pair from a bloke and am havin a look at them on Saturday. They are apparently in good nick. How much should i expect 2 pay. There on a a15 manifold 2!