Got some MSA headers since there was a problem with the stock manifold.  The engine builder supplied some thick washers and the R&R shop owner thinks they're OK. I don't want to second guess those guys since they both know way more than me. Thought I'd ask though. If I need them I can order them today. Header is out getting some ceramic since the coated ones aren't available for awhile. The spacers are available at MSA:  http://www.thezstore.com/page/TZS/PROD/classic19o/14-0373

 

 

Edited December 2, 20178 yr by Stanley

Funny that even MSA can't really figure out what to call them, and both attempts are kind of wrong.  Nissan called it a "yoke", probably because it spans a distance to clamp two separate parts together.  But it's really a clamp.  It's a specifically designed piece of metal.  It's cone shaped to clamp the two manifolds to the head, via just the edges of one side, and to allow the nut to ride on a curved surface on the other side.  Probably to allow for differences in thickness between the two manifolds.  A flat piece of metal, like a thick washer, would be caulked, and put a side load on the stud or bolt if the two manifolds were not exactly the same thickness.

Anyway, that's the way I see it.  For as crude as it looks, the yoke is actually a subtle piece of engineering.

Post a picture of the flat washer/spacers if you can.  Let's see if they have any shape to them.

http://www.carpartsmanual.com/datsun/Z-1969-1978/engine-280z/manifold-egr/from-aug-76/28

 

If you loosely put those on the studs you can hang everything and come back to tighten it all up.  Cupped side to the head.

OK. The old ones are probably shot.

Didn't get a photo but they are cupped on one side.