Rebuild 18R cylinder head *with pics*

[mike1980ra40]

Got some photos for ya. the 18R in this one is the "newer" one there were two types.

parts of the emision system that where removed were
black and yellow VTV's
EGR valve and manifold and modulator (replaced with extrators)
Emission ports on carby removed and blocked off

hope it makes sense.

[timbosaurus]

Looks good mike... i got some shots of my non-emmision setup as well as the original 18RC too. will post them up for reference soon.

[timbosaurus]

Hi guys,

These are some pics of the emission-controll-equipped 18R.

Air pump.

The air pump seems to draw filtered air from the air cleaner, run it through a vacuum controlled solenoid and directly into the number four cylinder.





I would've thought this would have been to lean the mixture out on low-load situations like highway cruising, but it strikes me as odd to only feed it into the one cylinders inlet.

Mike, you suggested the air pump feeds air into the exhaust to aid post-combustion burning of the fuel to reduce HC's. This setup seems to have no link to the exhaust at all!

Hopefully you might be able to clear this up for us

*edit* added extract from parts catalogue

[timbosaurus]

These are the diagrams of the air injection system. Brain is too fried to deconstruct what each hose does, and post my pics of what it looks like on an actual engine, but i might get there eventually





Timbo

[timbosaurus]

This is the 32/36 weber-equipped manifold with no emission control gear on it at all.



All it has is the fuel line, one small vacuum line for advancing the dizzy, a large vacuum line for the brake booster, another large vacuum line for the PCV valve (i guess it could just breathe into a catch can and eliminate another hose?) and another large hose (that i forgot about when i labelled the pic) that goes from a pipe (not valve) in the rocker cover into the air cleaner assembly. I've no idea of the necessity of this hose.

It would be nice if the charcoal canister was hooked up to another vacuum line too, but it is currently disconnected.

It seems all holes previously needed for emission control gear have been plugged up with anything the fits in the hole with the same thread

[stradlater]

I think it'd just come down to them having to find a spot to put the air pump outlet, and the only space was beside cylinder four.

I guess they figured it would just 'sort itself out'.

[timbosaurus]

Thanks Strad... do you think the idea of the air pump is to lean the mixture out and improve economy in no-load situations?

[stradlater]

I did once know what it was for, I don't recall properly now,

BUT, I'd be inclined to think it is to lean out the mixture a bit to give a better burn and then lower the emissions.

IE, more oxygen, more clean burn, less nasty unburnt fuel coming out.

Maybe something like that.

[Screamn_Sleeka]

Thanks, those pics are great.
Although, ive got some trouble in paradise, all my pipes are pretty screwd up...
Hose 17343, from the first diagram timbosaurus posted, is missing, both ends are blocked, looks so dodgy, it could only be the work of a mechanic.
23275 Valve also does not exist (figure 2), neither does its bracket 90461-08079, and i can not see a provision for it on the 17670 Valve (labelled in fig 1), ie there is no tapped screw hole.

On top of my thermostat/head water entry place, there are 2 provisions for small vacuum pipes, but both are missing, any diagrams or pics of what these are/where they go? The thing has the Niponised (/watever) logo, is that jsut a/c stuff?

I dont have a digital camera so unfortunately i cant take any pics

Mike, so is that a electric dizzy u have made with 21R parts or somthing?
My vac advance does not work on my dizzy, and im only getty the mechanical advance, the diaphram is stuffed, and instread of repacing it id rather make an electic dizzy, as i will need it for my 18RG anyway.

timbosaurus, god damn it all looks so much better with a simple weber setup!

[timbosaurus]

ah... there is a fair bit of info in this link about old emission systems if anyone is interested

http://www.familycar.com/Classroom/emission.htm

The 18R emissions system seems to be a little unconventional. Rather than using an air-pump for the air injection to remove HC's, and an EGR system for leaning the mixture out for efficiency, it seems to combine the two techniques and uses an air-pump to lean the mixture out (only under low-load though)

There is also a pipe to feed warm air that is surrounding the exhaust manifold back into the inlet, presumably to warm the engine up to operating temp faster. Where the pipe should be is shown below in red, not actually attached



I cant really see in these pics where the air comes from to feed into the exhaust for the air-injection side of things. But i would imagine that these are the parts.

[stradlater]

Why can't you just take it all off and then block up the holes?

[timbosaurus]

Thanks, those pics are great.
Although, ive got some trouble in paradise, all my pipes are pretty screwd up...
Hose 17343, from the first diagram timbosaurus posted, is missing, both ends are blocked, looks so dodgy, it could only be the work of a mechanic.
23275 Valve also does not exist (figure 2), neither does its bracket 90461-08079, and i can not see a provision for it on the 17670 Valve (labelled in fig 1), ie there is no tapped screw hole.

Hose 17343 should be there. As Mike mentioned, i think that will cost you a bit of efficiency as it will not lean-out when possible. My engine is missing 23275 valve and associated crap too, so i think that might be a difference between 18R-C (which we have) and 18R-U (which is in the pics). Only guessing though.

On top of my thermostat/head water entry place, there are 2 provisions for small vacuum pipes, but both are missing, any diagrams or pics of what these are/where they go? The thing has the Niponised (/watever) logo, is that jsut a/c stuff?

ummm... are you talking about the 23271 valve in the second parts pic? I dont have a good pic of that, but the parts picture should help you out with where the hoses go to. As for what they do.... i've got no idea! My engine doesn't have them

timbosaurus, god damn it all looks so much better with a simple weber setup!

Yeah, i'll take some more pics when the head/manifolds are back on (hopefully this w/e) but it looks so much neater without the emissions stuff. It's certainly no show-car engine bay (far from it ) but it is so empty, easy to understand and work-on and easy to keep clean and leak free!

Timbo

[timbosaurus]

Why can't you just take it all off and then block up the holes?

Nothing really stopping anyone. You've just gotta be sure to not leave anything unconnected, and make sure all the plugs seal properly.

And with the original carb (possibly with the weber as well?) the efficiency will be hurt running without the air pump, so it would be wise to make sure it is there and working properly if nothing else.

Timbo

[mike1980ra40]

Mike, you suggested the air pump feeds air into the exhaust to aid post-combustion burning of the fuel to reduce HC's. This setup seems to have no link to the exhaust at all!

my thoughts precisely, what I've written came straight out of a toyota workshop manual. in english it think it goes like this
exhaust recirculated into the intake to reburn it and help lower HC's and lower combustion temp, air pump compensates
for the exhaust being recirculated by pumping in clean air. the amount of air being controlled by the mixture solonoid
thingy bolted to number 1 intake.

Mike, so is that a electric dizzy u have made with 21R parts or somthing?

that dizzy is from a 16R, converted with the lumnition optical setup.
I got my kit can from holley parts wholesalers in perth and
will suit 4, 6, or 8 cyl motors. (kit has 3 chopper blades.)

16R dizzy's are great because the have a little plastic cap on the side
which covers a hand turnable srew for fine adjustment of the timing.
also by having this setup means that the ignition system can be imobilised
and it is impossible to start a carby motor even if you think you've hot
wired the car, eg battery to coil bump start it will not start at all.

as i will need it for my 18RG anyway.

i'll get the part number for the dizzy I've got and also take a few other
photos for ya. hunt around any wrecking yard you can for a 16R dizzy.
if you have the cash get (cost around $400) the optical setup. no more
points to replace ever

http://www.lumenition.com/new/main.php/optron/

[Screamn_Sleeka]

Mike, that 16R dizzy sounds good, is it completly 100% bolt in?
What is the advantage of that lumenition gear as opposed to other electric ones?

timbosaurus, those pipes i am talking about are not the 23271 valve,but valves coming out of the thermostat, both are unplugged and i cant find any pipes for them to go with.

Ive jsut spent all day fixing my computer, and ive forgotten what i was going to ask now...

I do have a pipe that seems to be going directly into the exhaust, the one that is covered with ribs, looks like a spring. Im totally lost with what has been said, but i think it would be putting new air in, probably lowers the % of CO.

Mike, from what i can see you have done away with all ur pipes except, charcoal - carby pipe, and cam cover - air pump - intake pipe? Ur air pump one is going to manifold 3? Mine is designed for manifold 4, and 3 is for a pipe to my brake booster. Do you have a manifold pipe to ur brake booster?
Do you still have the air pump - exhaust pipe?
The cam cover pipe, (front most one) that u are using that transparent pipe, where is it going?