I think the idea is to spread the load over more area of the manifold ear casting...so the best (in my humble opinion) is to have the flat towards the casting and the convex side towards the nut....
How did you determine which direction those washers go on? It almost seems like the rounded side should go towards the manifold and the flat side against the nut
In reality those washers were pretty flat on the backside, but they are thicker than regular washers and shaped as you see in the picture....I'm sure they help distribute the load even if they are not really concave on the back....
My 3A is in need of a valve adjustment and while I have the fender off I figured I would replace the intake/exhaust manifold gasket as I've had an annoying exhaust leak there for a very long time.
Remembering this thread, I just this morning ordered the two washers from Ron Fitzpatrick.
I also took a fresh look at the M38 service manual and noticed it calls for "13/32 ID flat washers" on the two center studs. No mention of any special concave washers. I'm still going ahead with the concave washers but I figured it was worth noting here that it appears they were discontinued, at least for the M38. I wonder if it was determined the flat washers were just as effective or if there was another reason for simplifying the parts requirement a bit?
I learned over at the 2a forum that there is supposed to be a special thick washer on each of the two innermost manifold studs. This washer is concave on the one side to allow even tension on the two intake and exhaust manifold ears.....
Anyone have a picture of one, or dimensions? I'm told that they are about 1/4" thick, slightly rounded on top, concave on the bottom....
