differences between 3rd valve cover (plug alley cover) plug/bolts

[Cyrus]

i have 3 different types.

one is the elongated one with the tapped hole in the center of the head. pretty sure that one goes at the back of the head over cylinder #6.

then there are the other 3 plugs. 2 of them have chamfered heads, and one of them has a regular flat-edge head. i am wondering if placement order of these 3 plugs is important. as far as i could tell, this bevel (or lack thereof) is the only difference between them, so it seems unlikely to matter. just asking cuz the TSRM doesnt have anything to say about it.

thanks!

 

[Cyrus]

nevermind, figured it out.

the flat-edge pieces are meant to go into the recessed part of the alley, at the same height as the spark plugs holes (EPC 11117E). these seem to seal the coolant channels in the head. the chamfered plugs seal the top of the head (when combined with the #3 valve cover as a gasket), where oil is circulated to the cams (EPC 11117G/1). someone swapped a flat-edge one for a chamfered one on my head, but i think it shouldnt be a problem.

 

[IJ.]

Tapped one to the rear there's a bracket to hold the heater hoses stock that screws to it.