Chamfered washers

[MOTORHEAD]

I know this is a stupidly simple question, but I just can't remember which side is up !!! My main bearing cap and head studs have chamfered i.d. washers under the nuts , does the chamfer side go under the nut, or towards the cap/head ?

[Ronbo]

If your using studs it doesn't matter. The chamfer was for bolts.

[MOTORHEAD]

Thanks Ron.! One more shelby alum block trivia question: I just noticed the washers for the main cap side bolts have a chamfer on the OUTSIDE DIA. on one side only ! Any clue what thats for? While contemplating this re-build I realized that with only 478 mi on the odo, this will be the 3RD time this engine has been built-up !!! (don't ask !!!!!!)

[Ronbo]

No idea why the outside needed it. On the side bolts (since they are bolts) you would want a slight inside chamfer. This is to provide clearance for the concave transition from the bolt head to the shank. (a sharp 90 deg transition is a potential fracture point) Perhaps the machined pads on the block needed it at some time? (mine were larger than the washers)

Most washers have a "sharp" side caused by the stamping process, this should always be installed away from the bolt head.

In 99.9999% of all cases this is not a big deal except for space shuttles and cars that hammer the heck out of their drivetrains. Putting the washer on wrong won't make your fender fall off, but it's a good habit to have.