Easy, As said the computer controls the ignition. Just leave it in there to control the ignition just disconnect the injector wiring. Maybe a little fluffing round to get it working but I see no reasoning as too why it couldn’t be made to work. Or just go for one of the ignition only megajolt or the likes
For the carbs split the stock manifold just take off the top half and keep the bottom attached and block off the injector ports. Then get some r1 bike carbies as the are held on with rubber couplers.
The manifold is super super simple just a bit of plate to bolt to the ca lower half and some round tube for the carb couplers. Ca ports are 40x32mm at that point so a small squish and maybe a little porting and you’re away. You’ll probably have to make them short to clear strut though.
I reckon it could be done for $1500 if you could fabricate the stuff yourself. If not you could probably get it running for 1500 with a stock exh manifold if you made the bits for the intake manifold yourself and got someone to weld it up. There would be a bit of fiddling with the linkages to make the carbs work too.
Definitely doable though

I beg to differ its just an option, 200cc could be just enough to make
a difference with 8v instead of 16v.
Head shaved $60-80 expect to see 4% improvement per compression point.
maybe 105/111 will make 115/120hp.
Porting to remove short turn radius and casting slags $150-250
3 angle valve cut and re-seat $150
Mistu conrods $20-40 from wreckers get 8 to xray and machine $180
Camshaft $179USD
LPG rebate still 1750aud so you will get some money back if you
can get an injection manifold modified.
Carbs are too hard to pass engineering I would have thought.

Someone has a datsun 1000 sports sedan with a ca18de and it supposedly
has a distributor of the front camshaft from a Sigma can anyone confirm?

dude dont even bother with a ca20 theyre absolute crap...
get a ca18de...
would be way cheaper and much better
any questions then pm me..

ooh d that does sound very tempting, how much should i budget for that sort of work considering i'd be doing the build myself? so just for parts and getting the head shaved etc.? 7000rpm sounds about good, and the possibilty for 10.5:1 compression sounds real nice
and yeh pretty sure mine is making less than 100hp atm!
all the info is much appreciated

Megajolt lt Junior is cheap as chips and rids all dizzies forever.

If you can use the Mitsu rods on a balanced bottom end, extractors,
shaved head and custom billet camshaft (only 179USD for a billet!!!)
and use the efi manifold that bolts straight up and run LPG you can
have alot of fun.
To go further than that you will need 10.5 compression, bigger valves
and porting which will be cheaper on an 8v than a 16v.

remember your stock 8v ca20 has only 8.5:1 compression ratio
Horsepower, 102hp @ 5200rpm and worse if worn out.

Going from 8.5:1 to 9.5:1 will make gains, also the camshaft is made
to peak at 5200rpm so if you use beefier rods, compression and a
camshaft designed to peak at 7000rpm then you will see a good engine.

Otherwise find a cheap ca18de and go from there but will all add up
about the same. You either work 16v or use 200cc more with 8v will all
end up about the same in the end. 84.5mm bores can be taken to 85mm.

Its still possible to have electronic ignition without a computer. Maybe an decent aftermarket system like MSD or something equivilent?

And a CA18 and torque dont really go together, lol!

Well ignition is controlled by computer as well so imagine you'll still need it, unless you go for an old school dizzy somehow too.

I heard of a Ca18DE on carbs years back...in a 1200 too - in the 90's so it has been done at least once.

and in a 700kg ute torque from 1800 is realy a wory.

yeh cheers, just double checking that there's not some random feature that requires me to still have a computer. have done a decent amount of study regarding runner legths, diameters etc. thinking i'd probably go for some relatively short intake runners for some nice high end power, don't really care for low down torque.
thanks heaps

Copmuter was for staying EFI. Second hand carby prices will range from person to person but you could find yourself a set of 35DHLA dellortos or webber equiv. for around 300-400. The only problem with making your own manifold for an NA setup (turbo too actually) is that depending on how long your inlet runners are will have an impact on how the power is delivered and where abouts in the rev range. Extractors again wont be too hard to find, i cant remember off the top of my head if the CA20 exhaust ports are similar to the CA18 as you could then modify a set of CA20 extractors which are plentiful. I have a Ford Corsair that has the Ca20 in it and all i have done is fitted a K & N airfilter, a set of HiTech Extractors 4-2-1 through a 2 1/4 inch mandrel bent system, sounds quite nice and have a little bit mroe torque down low as well as more up high. All of that there cost me less than $500.