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Location: Brisbane
Registered: November 2002
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18R - what's this?
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Sun, 29 August 2004 12:19
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Heyyas
I bought an 18R carby & manifold for my RT104 Corona today, but it came off an RA28 Celica. When I bolted it up, I noticed that it didn't cover this hole - which from memory didn't exist on the RA28 head. I assume it is something to do with pollution gear, but if anyone knows where it goes, I'd be interested to know.
I also want to know what models of carby 18R heads came WITHOUT this hole as I now need to get one of these 
Cheers
Leigh
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Location: Tasmania
Registered: May 2002
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Re: 18R - what's this?
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Sun, 29 August 2004 12:26

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Without having a good look at it, my best guess is its a EGR port. (Exhaust Gas Recirculation). Some exhaust gas goes through a metal pipe, controled by a big diaphram, then back in the intake manifold. The exhaust gas is used as a inert gas, which lowers combustion temperature which reduces a cirtain toxic gas in the exhaust.
You don't need it. Weld up the hole.
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Location: Brisbane
Registered: November 2002
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Re: 18R - what's this?
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Sun, 29 August 2004 12:40

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Exactly as I thought, just amazed that Toyota had two different head castings.
I know I don't need the hole, but where does it go? A bit sketchy about welding it up as (a) I have to disassemble and clean the head to do it and (b) the chance of welding splash on wherever the hole actually goes is no doubt pretty high!
Does anyone know what models did/didn't come with this?
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Location: Rocklea qld
Registered: February 2003
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Re: 18R - what's this?
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Sun, 29 August 2004 12:40

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is say just get a manifold that covers it if possible. rather then risking damage by welding it up. BTW nice pic of my commodore boot hey.
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Location: Brisbane
Registered: February 2003
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Re: 18R - what's this?
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Sun, 29 August 2004 13:08

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i think that hole is in the 18RC heads only - earlier 18R only used used exhaust gases to heat the choke up and heat the manifold 'plenum' under the carbi.
mine has this hole blocked up with a threaded rod with hex socket pressed into it. once attached, it has been ignored ever since.
it originally went to an EGR valve mounted on the manifold, or if you were really lucky, to egr valve attached to a flange below the carb.
18RC only major improvement was a better upper cam chain tensioner (spring plus oil pressure instead of just a spring) ... i think. heads are similar - maybe compression is different for the emissions model.
advice: find any bolt that fits it, attach said bolt, then forget.
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Location: Rocky Mountains, Canada
Registered: May 2002
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Re: 18R - what's this?
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Sun, 29 August 2004 15:25

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What thechuckster said...
Its for the EGR on the 18RC, the 18R didnt have it.
Plug it up.
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Location: Brisbane
Registered: November 2002
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