"Flat Spot" in Aisan Carburetor

[Tham]

Sorry, but didnt bother to read all this thru...

If this is still the situation, you have to clean the accelerator
pump jet! When it works, the squirt is wery noticeable.

I've bought a repair kit and will get
the whole carb cleaned soon as I can.

As for the idle solenoid, you sure can use that bolt or even
shotened valve will do. Nothing gets mesed up or gets
any leaks by there.

Thanks for the info ! You've cleared my fears
about any vacuum leaks caused by using
that bolt.

Intake leaks are main reason for K engines
not to work properly.

I've changed the intake/exhaust manifold
gasket recently. The older one was burnt
at the edges, obviously leaking too, near
the holes for the bolts, because the
mechanic had failed to tighten them previously.
(Mechanics in Malaysia aren't very reliable -
hardly any of them are professional enough
to use a torque wrench, let alone have one).

I've also had this newer mechanic fabricate
a paper gasket for the carburetor mount.
The previous mechanic never placed one
on top of the fiber plate where the carb is
mounted. But I couldn't see any gasket
there too, when the stock carb was taken out
a couple of years ago.
I'm not sure if it was assembled in error that way
at the factory - but that mechanic told me that
Corollas normally don't have any gaskets there !

pvc valve should be tested and make sure
your carbie hasnt got a worn axle, it tends to
leak there.

I've just bought a new PCV valve.
Er ..... where is the carbie's axle ?

[Tham]

you seem to misunderstand what you are trying to do?

30 degrees at idle??

Er ...... was just trying to see if that caused any
knocking when taking off. I don't have a timing
light, so that was basically an estimate. Can't
do static timing either with an electronic dizzy.

perhaps by using a bolt to fill the "hole" you have left open the internal passages and it now doesn't work how it should?

As Toycrash mentioned, using the bolt
shouldn't cause any problems, since there
is not supposed to be any vacuum emitting
from that hole. I believe the solenoid is just
meant to cut off the idle jet when stopping the
engine. But I will replace the solenoid and see
if there is any improvement, just in case.

you should check the operation of the vaccum pots on the dizzy, and then set as per normal.. check where the vacuum source is on the carby too.... manifold or ported vacuum?

Both vacuum stages on the distributor appear
to be functioning, but I think the advance is
insufficient. Both stages must be connected
via a common T-joint, connecting either stage
alone does not seem to produce any advance.
Seems like a very odd diaphragm design.

The vacuum source on the carby is the normal
ported inlet just on top of the throttle butterfly.

start by ACTUALLY checking the advance and vacuum mechanisms of the dizzy... then clean the carby properly.. if you don't know how to, then it's time to learn
if the carbvy has been sitting around for too long, it might be stuffed.
you should at least open it up and check the main jets are not blocked, and the power valve works correctly...
etc[/QUOTE]

I'm getting it taken apart and cleaned soon
as I can. I've bought a repair kit.

Just to give any example of the level of
expertise in carb cleaning in Malaysia, I asked
this younger mechanic the other day if he
could do it for me. He replied in the negative,
explaining that a carburetor is a very complex
and sensitive unit, and it shouldn't be opened
up and messed around with if there wasn't
any major problems. He said he had seen cases
when carbs were opened up and cleaned,
then on reassembly and reinstallation, the
exhaust gave out white smoke on running ......

Another mechanic told me he had to reassemble
back completely disassembled carburetors,
brought in by car users. They had taken their
cars earlier to other not-so-proficient mechanics
to have the carbs cleaned, but who did not
know how to reassemble them back properly
after taking them apart.

Thanks.

[Tham]

Oops, posted the above message twice.

[Toycrash]

I'm not sure if it was assembled in error that way
at the factory - but that mechanic told me that
Corollas normally don't have any gaskets there !

No gasket, just a bit of gasket glue or similar.

Er ..... where is the carbie's axle ?

Where your throttle plates are.. They are usually fited to axle

[Tham]

I had the carburetor taken apart and cleaned
by another mechanic the other day.

He poured petrol into it to flush it out, and I
was amazed at the darkening in colour as it
drained into a pan ! I didn't know that amount
of oxidation could occur when a carb lies idle
for a year.

Then he blasted it with compressed air. He
also cleaned out the fiber mounting plate,
and finally made a paper gasket for for both
sides of the plate.

The engine runs somewhat smoother, and the
flat spot appears to be eliminated or much
reduced. There is still a mild "tugging" as the
car accelerates though, but overall things
have improved.

[oldcorollas]

a couple of things before i give up....

aluminium oxide (the carby is aluminium) is white... not dark. so what you saw coming out from the petrol was not oxidation.

the petrol evaporates and the colour dye becomes a hard residue.

i was meaning you should get a manual for your car (from ebay or similar perhaps) and just do it yourself...

as you keep saying, the mechanics in your area have absolutely truly NFI, and there is no point going to them

that tugging.... going lean.... is likely due to manifold leaks...

[Vios-GT_07]

as you keep saying, the mechanics in your area have absolutely truly NFI, and there is no point going to them

another reason why i'm not welcome in malaysia..

coz i've noted two people quote me, and i'm not sure if they're laughing at me or with me..
/end rant

[Tham]

Sorry about that, OldCorollas.

I'll try to do it myself from now on.

I'll have to find a Haynes or Gregory's manual
for the 4K and check out the Aisan's mixture screw's
settings.

The intake/exhaust manifold gasket was also
replaced recently. The older one was burnt
at the sides and was definitely leaking as you
had guessed correctly. The previous mechanic had
failed to tighten some of the mounting nuts
properly. A pic of the old gasket is shown below.
I'll try to get a torque wrench and replace it
myself again this time.

A vacuum gauge hooked up to the intake
manifold (the hot idle compensator's inlet)
reads a fairly steady 15 to 16 inches Hg,
I checked up my old timing light's tune-up
manual as well as my old Reader's Digest
Car Care Manual and they appeared to diagnose
this as loose piston rings. The Reader's Digest
vacuum readings appear to be somewhat different
- normal at a fast idle is 15 to 22 inches Hg, versus
17 to 21 for the timing light's manual. It also makes
an error in illustrating one of the sources to tap
the vacuum as the distributor's advance inlet.

Wished I knew where I put my old compression tester
which I bought with the timing light.

[oldcorollas]

if i was in Oz, i'd send you a manual to borrow so you can do it youself... and talk you all the way thru it, but i'm not and don't have any old corolla stuff here...

vacuum can be affected by the idle mixture also.... you want to basically adjust the idle mixture to give the highest vacuum, or thereabouts.. and timing also has an effect.

if you could borrow a compression tester, it might help to diagnose if the engine is just stuffed..... then again, K motors have been known to run with all the rings broken.....