It's the same for me. The steering rattle but if I put my hand there, the rattle stop.
That means steering rattle is not mounting problem??

No idea about the Weber; in the mudah ad page, there
is one Wira carb for RM299 in Kepala Batas, near to Kedah,
looks the same as for Iswara.

Weber carburettors, particularly those 32/36 types, are gas guzzlers.

Most mechanics should be able to get you a "half cut" used one
for maybe $ 300 to 400.

A brand new Aisan variable venturi type will set you back $ 1,300 - 1,400.

Lots of China made ones on Ali Express, but not sure of their reilabilty.
This guy is selling his for $ 180.

https://www.mudah.my/Carburetor+iswara-64111928.htm

Thanks for all your good diagrams.

Do you find this older 8-valve carburettor more economical  ?

The second butterfly, or venturi, only opens at 4,000 rpm
and above.

That's why they call it a progressive downdraught carburettor.

Most times, the second butterfly never does open - in my older
Toyota Corolla KE70 - it never did, so much so that the linkage
jammed tight over the years (first the older carb, then the
new replacement carb).

That carb used a mechanical linkage to open the second butterfly,
rather than the vacuum diaphragm operated types on many other
Aisan, Hitachi and Mikuni carbs.

If you stepped on the throttle a bit too much, particularly when
starting as one stupid mechanic who tried to show me the
"correct way" of starting an engine by flooring the throttle,
the second butterfly would jam fully open, revs going up
to 6,000 rpm, nearly breaking my timing chain and wrecking
my engine.

So I disconnected the linkage to the second butterfly, making it a
single venturi carburettor only.

I remember the main jet on the primary venturi on this carb was about
0.103 inches. Yours is probably around there too.

Those Australian guys in the Toymods and Rollaclub forums
said that Aisans are jetted too rich, so they usually replaced it
with a smaller jet, about 0.096 inches.

The main jet on the variable venturi one was stated as 0.118
inches - that's why that carb is a gas guzzler.

Right now my 8v carb is not in its best shape. I can see fuel leak through the linkage. I already bought keyster carb repair kit for RM35 at auto shop and we'll see how it goes.

I heard old 8v carb has the same vtec effect as it have two butterfly but im not sure how true is this.

1) Did the old carb require you to pull the choke, or you can
start straight away?

2) Enclosed is the page from Iswara owners manual for
starting with choke. 

3) The fuel spurting out when pedal is pressed is the
acceleration pump compensating for momentary lean
intake when the pedal is floored. So maybe your acceleration
pump is not working, could be the linkage or internal parts
problem. Maybe you can observe the linkage movement
when the pedal is pressed.

4) One way to confirm if it is too lean is to spray a bit of
carb cleaner down the carb throat and then try to start.
(Carb cleaner acts like fuel.)

You can also see it in the attachment.
I bought this carburettor, original Aisan, at that time from
Takara Auto in Jln Bacang, off Ipoh Road, for $ 450.

The tiny jet of fuel you see spurting out when you move
the throttle linkage (even without starting) is from the tiny pipe
at the side of the carburettor throat, on top, pumped out by the
accelerator pump bellows.

It's meant to compensate for insufficient fuel coming in
from the primary jet when the car first moves.

If that is clogged, as in my Toyota once, you will feel the
car hesitating for a moment before picking up again, as
you move from standing.

This mechanic when cleaning that carb once, passed a tiny
wire strand thru that small pipe to unclog it.

You have a timing light ? Try increasing the timing to 15 degrees.

What plugs are you using ?

Try increasing the gap to 0.035 inches, or 0.9 mm.

Adjust this first before adjusting your timing.

The NGK BP5ES/Y (Nippondenso W16EX-U and Bosch W8D equivalent)
are usually gapped at 0.032 inches or 0.8 mm at the factory.

That is about the optimum for a car with electronic ignition.

If you are using a normal two-venturi Aisan, the idle mixture
screw, turned outwards about 5 full turns after fully turning in,
should be about right.

This MItsubishi 4G series is known to be hard to start at times.

If it runs well after starting, just let it be.

How is your fuel economy now ?

I've had this Iswara since 2010 , so I would have changed
the carburettor in the older car over 10 years ago.
That Takara Auto is more of a wholesaler, and lots of auto
shops get their supplies from them.

So their prices are relatively cheaper. One auto shop boss
at that time was shocked when I told him I bought the Aisan
for only $ 450, so I guess the usual price in the normal retail
shops was more like $ 600 - 700.
When I was about to buy it at that time, I discussed with one of
the sales staff there that some people had suggested that
I modify the carb to a Proton Saga's.

His eyes bulged and said that will set me back easily $ 1,000,
presumably referring to the variable venturi model.

Which is correct. I had been told earlier by an Aerolite Auto
in Pudu (closed down since) employee, who drove an Iswara,
that he had replaced his for $ 1,400.
However, if you go to Takara to buy parts, be aware that the
boss, Mr Chong, is quite a "cocky" and rude man. Even
AME's boss, said he knew of his reputation.

I bought the Tama water thermostat from them for just $12.
However, they had only the 82 degree C rated one (which is
actually the right specs, since the thermostatic switch on the
radiator is set to turn the fan on the same temperature),
so I bought another Tama, 71 degrees, from AME Auto in
Sea Park later, as a spare. The boss,. Simon, sold it to me for $ 20.

How much did you buy your used Aisan ?  Did you get it from those
salvage yards ?

Is it this variable venturi carb ?

If you are also looking for a copper radiator, at least as
a spare, you can get one from this shop in Pandan Jaya
which I bought two weeks ago.

https://www.google.com/maps/place/YS+Radiat...fztCs0Q_BIIeTAP

Got it for $ 280, the one above, She said she was letting me
have it at the old price.

They had only one for the Saga there, but I guess she
can order another one if you want.

I heard from this mechanic who shares the same shop
as her that she gets it from Chan Sow Lin.

Another shop I enquired at Old Klang Road wanted $ 424 for
a two-layer copper radiator. Another is Segambut said
"above $ 350".

Copper is getting expensive, and not many
shops have copper radiators these days.

When he serviced your radiator, did he burp out all
the air bubbles by revving the engine at idle to 2,000 rpm,
after he had filled it up with water/coolant, with the cap off ?
The water level will drop for several days at it tries to
take up the air space.

Moreover, air in the system will make it run hotter.
Look carefully also at the core plugs - there are three or four
just below the intake manifold.

These tend to leak in old engines.

One leaked in my old Toyota.
Is your radiator the original single-layered Nippondenso
copper one since day one, or has it been changed
to an aluminium model ?

Either case, I'd suggest you buy a spare copper one
at the shop above at the good price she is giving now,
since copper radiators are getting scarcer and pricier
as time goes by.
The old copper one would have thinned out from corrosion
over the years, and the plastic tops of those aluminium ones
tend to leak from the inner rubber seal after some time.

That's why I don't like aluminium radiators.

IF you are sure of no leak anywhere wait for some days and keep refilling reservoir maybe there have been some air remaining and are discharging.
Other than that my first guess would head gasket .