I wanted to make sure that the engine didn't have any mechanical problems before I installed it in the car.  The main thing I was worried about was weak compression, which would imply problems with the rings.  I definitely didn't want to completely dismantle the entire engine and start figuring out how to replace cylinder rings and reseat liners properly.  That meant a compression test.

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Getting Set Up

To do a compression test, you need be able to turn over the engine.  Simply cranking it by hand with a wrench isn't nearly quick enough to test the compression -- you need to use the starter.  Since the starter attaches to be transmission bell housing, that means mating the engine and transmission as well as installing the flex plate.

I was initially worried that the starting torque would be enough to knock the engine over, but it turns out this isn't even slightly an issue -- the engine stays still on the floor during cranking, and is in no risk of moving anywhere.  There is no need to have it in the car or otherwise secured to do the tests.

Flex Plate

The starter engages the ring gear on the flex plate (or flywheel, if you have a manual transmission), so that has to be reattached to the crank.

Re-installing the flex plate isn't hard, but it is annoying.  The plate is held in place with seven short bolts.  There are two metal rings that the flex plate is sandwiched between, with the bolts passing through the first ring, then the flex plate, then the second ring before bolting into the crank itself.

The annoying part is that the bolt holes in these parts aren't evenly spaced.  I found the best approach to be to place one of the rings on the crank, rotating it until I was sure that all of the bolt holes lined up.  If I couldn't find one that worked, I flipped the plate over and repeated it until they finally lined up.  Next I placed the ring on the flex plate (the two protrusions on the edge flex plate should point away from the engine), rotating it until it lined up with the holes, then the other ring on the other side of the flex plate.  Finally, I could run a bolt through one of the holes, and put the hole thing on the crank and bolt it down.

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I really don't know why the holes aren't evenly spaced.  It would be so much easier, and I can't see any reason not to, but then I'm not a mechanical engineer either.

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