Rebuild 18R cylinder head *with pics*

[timbosaurus]

timbosaurus, did u notice and abnormalities to ur 4th cly? possibly from it having the air pump pipe?

you mean apart from the burnt-out valve which started this thread? To be fair, i dont think that missing the air pump caused the burnt out valve.

I might try to fit an air pump on my car and do some efficiency tests too. But my driving style is soooo inconsistant that i find comparisons difficult

[mike1980ra40]

Im getting very lost, the air pump pipe in the manifold is coming from the air filter?
Air Filter - pipe - air pump - pipe - 17670 valve - pipe - 4th cly manifold.

Are we saying that 4th cyl is leaned out, basically running the engine on 3clys? But pumping enough air into the 4th cyl to keep it going with out disrupting normal enigne turning?

air pump to manifold is there because like some previously said theres nowhere else to put it.
no 1 intake has the little filter thing that the AAP goes to. nothing on No.2 because its under
a heat sheild, Brake booster on No3 and air pump on 4. it wont be leaning out number 4
on its own.

[timbosaurus]

If that's the case, i wonder if there is anything stopping me from hooking my airpump up to the centre of the manifold where the PCV hose goes...



and using a catch can for the PCV.

[mike1980ra40]

gosh darn it you beat me to it i was think that while doing another post. well done!!
great minds think alike .... hehehe

[timbosaurus]

gosh darn it you beat me to it i was think that while doing another post. well done!!
great minds think alike .... hehehe

haha...

My last question prolly got lost in all the excitement, just wondering what is the difference between the 18R dizzy i posted about 6 posts ago, and the 16R dizzy you have converted to. all my 18R dizzy's have the adjustable knob.

[18rc turbo]

Both my dizzy's have the adjustable knob as below.

These are standard 18R distributors. Are these the same as the 16R dizzy's mentioned above? Or am i missing something?

.

Just to confuse the issue slightly...

I have 2 18RC's, one has a nippondenso distrubutor which is the one with the adjustable knob, the other one is a bosch distributor that doesn't have the knob. As far as i know, these are both standard distributors for the 18RC, every parts book i see listed has two sets of points for an 18RC, one for the bosch dizzy, one for the nippondenso dizzy.

This is a pic of the bosch dizzy

[18rc turbo]

to answer your question there isnt any difference (correct me if im wrong anyone)

[Screamn_Sleeka]

i wonder if there is anything stopping me from hooking my airpump up to the centre of the manifold where the PCV hose goes...

Thats exactly wat i was thinking.

I forgot u didnt have ur air pump pipe before.

thanks mike, that combination makes more sense to me.
shifting at 3500rpm i consider a drag race!
but i dont get the econmy to show for it.

My 18R-C dizzy does not have that adjsutment thing, and it has nippondenso printed everywhere?
The dizzy looks like its been made to have the possibilty of the knob, but a hole hasnt been tapped out or anything.

[Screamn_Sleeka]

haha...
what is the difference between the 18R dizzy i posted about 6 posts ago, and the 16R dizzy you have converted to. all my 18R dizzy's have the adjustable knob.

What are the production years?
If they are both from ra40's are they round headlights?
my square headlights ra40 has no adjustment, although looks different to 18rcturbo's

[18rc turbo]

my bosch dizzy is in my ra23, the nippondenso one with the adjustable knob is in one of my ra28's. One of my mates used to have an ra40 coupe with the round headlights, and he had an adjustable knob too.

[mike1980ra40]

please excuse the crudness of this schematic I drew it up out side in the cold about 20 mins ago .... this is basically how my 18r is running now.

to answer a question from tosco i think(or was it timbo...) any way .....
benifits of the optical dizzy setup are, a way stronger spark, it nevers fails and you very
rarely have to adjust the timing (if ever). the inital cost my be a tad off putting, in the long term
saves money on points, better running etc and it can be imobilsed where points setup cant.
I have had this ignition system for 6 years now and it has never given me a problem.

edit
actually its been 8 years ...

[mike1980ra40]

Just to confuse the issue slightly...

I have 2 18RC's, one has a nippondenso distrubutor which is the one with the adjustable knob, the other one is a bosch distributor that doesn't have the knob. As far as i know, these are both standard distributors for the 18RC, every parts book i see listed has two sets of points for an 18RC, one for the bosch dizzy, one for the nippondenso dizzy.

how bout some more confusion, I have 2 18r's as well, the other dizzy is different again to whats already been illustrated here, it has two vacuum ports on the diaphram (one blocked off) ill post a picture tomorrow.

[Screamn_Sleeka]

alright! now were in business!
that diagram is great mike, the only real differences to mine is that i dont have the air pump pipe that goes to 4cyl manifold (yet) and that my vac dizzy advance does not go though the thermostat, it is a direct line from vac to carby/manifold. I dont think this matters, as i took that thermostat thing off and as well as loosing 1/2 a litre of coolant i saw that its just a huge bolt that msut have a hollow head to allow the vac to transfer between the two pipes.

Refering to ur diagram,
the TVSV thing, im think this actually has nothing to do with the head, its jsut screwd in to hold it there? the first pipe (closest to the head) is to advance throttle? the 2nd (middle) is what created the vacuum by stealing the presure from 1cyl manifold. and i dont know what the 3rd one does, cause i dont know wat a AAP is?

The 17670 Valve im assumeing is constantly pressurised by the air pump, but is controlled by the vacuum of the 1cyl manifoldm, where a vac line is connected. Although i dont know y they are slipt into 2.

I also dont know wat those small electric things (89570, 084600) do? they seem to only control the "fast idle cam breaker" - i dont know wat that does either.

Could you shed any light?

[mike1980ra40]

TVSV = Thermostatic vacuum switching valve - controlled by engine coolant thats why its
right next to temp sender.
AAP = Auxilary Accelerator pump

i did some digging to find this on an old harddrive .....

at a constant RPM AAP diaphram is pulled by the vacuum and fuel drawn into the aap
chamber. when you accelerate the diaphram returns by spring pessure and the fuel in the
AAP chamber is forced into the accelerator nozzle which richens the air/fuel mixture when
the engine is cold. once the engine has warmed up to normal temp the TVSV switches off
and the AAP is no longer used.

a typical fault when engine is cold and you try to acclerate hard is a detonation on number 1. that is caused by either a split diaphram in the AAP or the TVSV has been damaged by
fuel leaking through the split diaphram into TVSV

vac line from dizzy to thermo to carb wont make much difference, it's quite common to
bypass the thermostat.

084600 controls the fast idle breaker and that 084600 is controlled by 89570 and the two of
those, i'm fairly sure (without checking electrial shcematics) controlled by the emission computer.

some time next week I am paying a visit to a toyota workshop in the city to get a look at
there work shop manuals for the emmisions system on 18r's hopefully will be able to figure
out exactly what 17670 does.

hope that helps :-) brain strain .... good to get a work out

[mike1980ra40]

slightly off topic but just thought of it
Carby rebuild kit part number A10L which replaces AN-111
if you rebuild standard nikki carb on 18R, DO NOT follow instructions included about
float level adjustment. instructions sheet included is for the 20R carb (similar) float level
is to low and using that on an 18R carb will flood the chamber and cause a nasty backfire.
I found out the hardway ....