Hi Guys

I am thinking of upgrading my engine in the future. As you all know, I have the A12GX engine. I am planning on getting a A14 block with the 5 speed which should give me with my h145 diff about 3500rpm at 120km/h.
I want to make the A14 as close as possible to GX. I want to fit the GX cylinder head, GX exhaust manifold which will be cleaned up and powercoated, GX cam and GX distributor.

My questions:
1. I have fitted a pertronix ignitor kit for the distributor. Either I want to fit the complete GX distributor or fit it into the A14's distributor.
Is the points being used the same for A12 and A14 engines? Why I am asking, is I just want to know if the ignitor system will work on the A14 distributor.
2. When using the GX exhaust manifold, will it fit or is the A14 engine taller giving a possibility that something might be in the way or even the exhaust manifold being too small to flow a 1400cc.
3. Can I straight fit the cylinder head or is there something I must drill. A oil hole or something.

Any info appreciated

Hey mate, use the GX dizzy with the A14 bottom plate, that way you have the correct advance curve for you GX Su's.

Exhaust manifold should fit no worries, head does interchange but you have to do something to get the oil to the top of the head, not sure exactly what, do a search, plenty of discussion on that.

EDIT: I think you actually have to fill the oil hole to use the early head on the later block, its the 74+ heads that have a different bolt to get oil up to the top of the head. Someone will know more.

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Hey WhiteSedan
You read my mind. Yes, I am going to use the SU's aswell to try and keep it as original as possible. Only the engine number is going to change with the addition of A14 instead of A12.
With the bottom plate I presume you mean that plate that is just underneath the distributor. How is it fitted to the distributor.
Is it just bolted? Do I need to calibrate the plate or something?

A small mod is necessary if you fit a LATE HEAD on an EARLY BLOCK, but the reverse [early head - late block] should be a straight bolt up deal.

The A14's left side engine mount sits some 50mm [or so] further back than the 1200's, but I think that the manifold will still fit up OK. From memory, the 120Y/B210 GX used the same exhaust manifold but on the later type block & that worked fine.
Are you sure that powder coating the exhaust is OK? Do they make a suitable powder coat for exhaust manifolds?

To make it all fit & work like a factory deal, you will need the 1974 & later crossmember so that the engine just bolts in & to help pull off the deception, you could make an alternator mounting plate to allow your electrics to remain on the original side.

The distributor advance curve is more tailored to the cam timing, so a mild 'sports' cam that is close to the original 1200 GX timing will be just perfect.

Yep just unbolt the plate from the dizzy, 8mm spanner, swap them over, you shouldnt need to calibrate it.

Time it by switching ignition on, get pully to 8

One other thing, get a 74+ ute engine crossmember, then you dont have to worry about engine mounts, also fuel pump gets in the way with standard crossmember, forgot to add that.

Hey Dodgeman.
Can I presume that the GX head will then bolt up to the A14 block without mods?

Powder coating? No, it is called POWER coating.
It is almost like powder coating but as they call it "space technology used on the space shuttle for heat reduction"
They use it on exhaust branches, turbo manifolds and turbo housings and you can even do Pistons and the inside of the cylinder head on the valves and combustion chamber. Apparently it helps against heat buildup and of course rust.
Also can prevent pistons from burning holes in them.

With this conversion, I am going to get a new crossmember that is cheap here. It will solve problem of old crossmember with new engine fitting.
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This is why I am going to use my GX cam aswell. I can always sell the A14 cam and distributor for a few bucks.

Quote:
Early head = Datsun 1200
Late block = A14.

This is the plan for me, I have my 1200 GX head all ready to go, except that I am using an A13 engine which is the same as a 1974 & later A12 engine, but with a bigger bore.
Think of it as an A14 with a shorter stroke & deck height.

The GX exhaust manifold is the factory competition department's recomended exhaust for cars used in Rally applications. These engines were bored to over 76mm & this made them only a few CC's short of 1300.
If it's the factory recomended item for a 1300 race engine, then it will be just fine on a 1400 cc street engine.

Dodgeman, I am curious now.

Where did you get the detailed information about the factory racing departments engine modification details?

Can you maybe give me more details about what they did to the A12GX engine for racing purposes. Maybe I must keep mine A12GX because I have a complete spare GX engine at home and just make my original a complete rebuild but to factory racing specs.

What do you guys think.

I have a copy of the factory 'Competition Tune-Up Manual' for the Datsun 1200 & the info comes from there.

The big bore forged pistons are NLA, but by using A14 pistons on A12A rods you can get pretty much the same thing, but more street friendly & affordable. My own 1200 GX engine is currently at 76.5 mm bore size with first oversize A14 pistons. [It was first built in the early 80's & now rests, headless, against the wall in my garage.]
I bored out the little end of my 1200 rods to allow the bigger pin of the A14 pistons to fit & never ever had a problem, but I prefer the A12A rods as they need no mods. The B310 short stroke A13 engine would have the same rods, but would be harder to find as this seems to be an Asian-market-only engine.
If you are going to bore out A12 rods, then get some later ones, say from about 1980 [B310] as these seem to be made from the same forgings as the A12A ones. They look to have more 'meat' around the little end & would be a safer bet.

If you have a spare engine, then this could be the way to go.
If you can't get a big bore head gasket that's made for the 1200 engine, then use an A14 one & simply use a suitable wad punch to make the extra hole that the 1200 needs for rocker oiling. This is what I did the last time I built my 1200 engine & it worked perfectly.

To build your engine to factory racing specs will be both difficult & very costly as just about every factory racing part is now a collector item & is priced as if made of gold.
Personally, I say, stick with the GX induction instead of the factory twin Mikuni Solex race instalation. To quote from my manual, .......

"The SU [Hitachi] twin carburettor, which is standard equipment for the GX, is most suitable for rally use."

A full factory race engine would also not be much fun on the street, as it is designed to be operated at racing speeds, which causes problems with La Systeme' [the Police] as well as being difficult to drive in town.

My big bore 1200 GX was so good, that as a result of owning & driving it, I became the dedicated small-Datsun man that I am today.
If you can get a serviceable 56A five speed, then grab it. It's more fun than an extra 25 hp. Much more fun.