18RC CYLINER HEAD

[cspies86]

hi guys, i have a 18RC cylinder head that has a passage that runs between no 2, 3, and 4 exhaust ports with a grub screw above these ports as well.  Was wandering if anyone can tell me what the function of this would be.  It is not shown in any parts diagrams that i looked at. I am a bit curious to what it may be.

[trentmeyer23]

Oil or coolant passage?

[cspies86]

hi trent,  neither oil or coolant run through this, that is why i am a bit curious.  I probably should have said that, for example, if you fill one of the ports with water it will run into the other twp ports through this passage. I thought maybe it could be to regulate exhaust pressure, but why only on 3 ports not all 4.

[Hiro]

Got any photos?  My guess would be that it's part of the emissions package, so either EGR or secondary air injection ("smog pump")

[trentmeyer23]

3 hours ago, Hiro said:

Got any photos?  My guess would be that it's part of the emissions package, so either EGR or secondary air injection ("smog pump")

I did think that, but though it may not have had that due to age.

[Hiro]

14 hours ago, trentmeyer23 said:

I did think that, but though it may not have had that due to age.

18RCs had heaps of power-strangling emissions stuff (hence the -C, ie California Emissions spec).

[cspies86]

will try and get a photo for you guys.  when i first got the engine it had all the emission stuff already on it but nothing went to that. the grub screws are fairly siezed in there i would say they have never been undone since new.