I got tired of having to hold the engine down while I loosed torqued bolts so I came up with this simple jig.

I took a 2X2, cut it in half and mounted to my bench/desk in my garage. Then I took some old dog chain and cut it to length to stretch between the engine mount holes in the block and the 2X2s that I mounted to the bench. I fastened one end of the chains to the wood, and use bolts to secure the other ends to the engine.

If my explanation is too hard to follow, here are some pics so you can see what I did. I need to find some bolts that are the proper length to secure the engine instead of using the engine mount bolts.