Electronic Distributor for 4K Engine

[Tham]

I have just bought a Nippondenso electronic
distributor from one of the salvage yards, with
a built-in ignitor.

The vacuum advance diaphragm on this unit is
a two-stage type, with two ports, one on top of
the other. The one on the stock points distributor
of course has just one port for direct connection to the
carburetor's vacuum inlet.

The salvage yard owner gave me a T-joint to connect
the single hose from the carb to both ports of this
new vacuum advance. Alternatively, he told me that
those plastic/metal splitters for hoses of aquarium air
pumps could be used. I wonder if this is the correct
method ? My usual mechanic, as well as a car wireman,
told me that only the lower port should be connected and the
upper one left unused.

It also comes with what I think is a vacuum delay valve,
very similar to that show in this pic :

http://www.top-downsolutions.com/images/309050.jpg

Which port should this go to, and which side faces the
which ? Or can this be left out ?

Thanks to the very informative users in this great forum.

[bansheebuzz]

in regards to the duel diaphram, check to see if one advances the timeing plate and on retards the timing plate

[Toycrash]

in regards to the duel diaphram, check to see if one advances the timeing plate and on retards the timing plate

Both are for advance. It all depends what kind of setup you have and what basic advance do you run. About 10deg advance without vacuum advance would be nice for stock 4K. Then just test with only one diaphragm and then try with both connected.
Or you can change the old single diaphragm from old dizzy and run with it.

Basically most 4K's were designed to run with only one, the secong diaphragm was to give a bit more advance when you flat out... And is connected outside the throttlebodys butterfly.

[Tham]

The vacuum pump on my electronic distributor looks
very much like this one here :

http://www.japparts.com.au/products/...20Dis.%201.JPG

Then just test with only one diaphragm and then try with both connected.

I tried connecting the bottom one first, and the car
was not only very sluggish, it was accelerating
hesitatingly and jerkily, not like misfiring, but kinda
like something was pulling it back every now and then,
particularly when going up a slope. I wonder if it was
due to the vacuum delay valve connected though.

So I tried with both ports connected, and it sure made a
difference. Acceleration was better and smoother.
I tried with the vacuum delay valve connected to the
bottom port, or left out, and it didn't seem to make
much of a difference.

Or you can change the old single diaphragm
from old dizzy and run with it.

Will the old single diaphragm fit into this new
distributor ?

[oldcorollas]

did you set the base timing correctly?

[Tham]

The base timing has to be set at a minimum of 20
degrees BTDC. This has also been the case with
the old points distributor. Any lower than that, and the
car performs very badly and can hardly climb slopes.

The above setting seems extremely high for a standard
performance engine, and shocked me too at first, but
it was actually recommended by a mechanic who was
very familiar with this type of engine. (He also specialized
in converting 4A-GE engines for this type of car).
It sounds like he is correct. I tried setting it at about
15 degrees once and it was very sluggish.

Most engines of the 70's to 80's era in Malaysia are
usually set above manufacturer's specifications. For
example, that for the Datsun 1200, which is supposed
to be specified at about 5 degrees, is typically set at
10 to 15 degrees. That for the Nissan E13 engine, used
in the Nissan Cherry (called Sunny here), is 2 degrees
according to manufacturer's specs, but normally set at
at 10 degrees or above. I can't really understand why
my engine timing has to be set so high though.

I wonder if it has something to do with the poor quality petrol
we have over here, or the ambient temperature.

[Toycrash]

Did you remove the vacuum advance hose when you set base timing?
20 deg souds like something is wrong...

[Tham]

Did you remove the vacuum advance hose when you set base timing?
20 deg souds like something is wrong...

Yes, the vacuum hose was removed when setting
the base timing.

I even tried static timing, and the result was the same.
It had to be set at no lesser than 20 degrees. Wonder
if the crankshaft pulley has been installed in the right
position.

[Toycrash]

you can instal your pulley only for 1 and right position, BUT you can swap pulleys and cam gear covers and if you do that... well
Pull nro:1 plug out, measure the REAL TDC and check if the markings on your cover are right.

[cambelt]

Do you have good fuel over there or something ?

[Tham]

Do you have good fuel over there or something ?

Fuel quality over here is lousy. I think they might well have mixed kerosene inside or something.

Nobody knows what the gas stations here put in their depots
in the middle of the night.

"Super" is supposed to be 97 octane, but sometimes knocks
depending which station you fill it.

"Regular" is 92 octane. Filling this at most stations will cause
knocking and very poor performance.

[kingmick]

you would prob better to tune for 92 octane then. might help with the bad doses of fuel! dont worry it happens in australia aswell sometimes! or you could buy 20 litre drums of toulene and make up litre bottle to sit in the boot and put that in with every tank to help! work out reasonable cheap over there i would imagine.
and or keep a spanner in the car so that if it pings you can back some timing out of it.

[Tham]

you can instal your pulley only for 1 and right position, BUT you can swap pulleys and cam gear covers and if you do that... well
Pull nro:1 plug out, measure the REAL TDC and check if the markings on your cover are right.

Thanks for the advice.

I took out the No. 1 plug and looked at the top of the piston.

I turned the crankshaft pulley, noted the marks on the
cam cover, and the piston appeared to be right
at the top when it reached TDC. The distributor also
rotor also looked in its right position.

When I did static timing when using contact points the
last time, I had noted that the points were just about
opening when the pulley mark was one inch or so before TDC.

[Tham]

This was taken from the Hayne's manual on
the Toyota Starlet. I think it was based on
the 4K-E engine.

The electronic distributor looks basically
the same as the ones which some of us
have bought from salvage yards.

The connection diagram is for fuel injection,
but note that the vacuum advance for the
distributor's lower stage appears to be
taken from the intake manifold, with the
upper one going to the standard vacuum
inlet above the throttle butterfly.