Cutting 10 ft garage door in side wall of existing garage. Wall is 8x8x16 cmu's. approx. 24'' of parapet will remain above opening.joists run parallel to wall to be cut.any temp. support suggestions.I'm assuming I need some kind of support. Thanks.

Does the wall support the roof line ?

Are the cmu's hollow or filled ?

Sure will but if joists run parallel to this wall it is not bearing. You could use a heavy steel lintel or cut further up and use 2 2x12 as a header. Notch the wall for a pocket or use a wide support. You might be better off cutting all the way up, install your support and filling the void. You just can't hang 2' of block and expect it to stay there.

As for the temp bracing, maybe something like this...

http://i819.photobucket.com/albums/zz111/lacogada/tempbrace_zpse3534cfb.jpg (http://s819.photobucket.com/user/lacogada/media/tempbrace_zpse3534cfb.jpg.html)