When the dizzy is timed in correctly the HT terminals should face straight back towards bulkhead, so that they are parralel with the block.
If the cap is loose when fitted correctly the spring clips have been distorted, and as a result are not slightly bowed as they normally are, they are spring metal so just bend them until the spring clips needs a shove to engage the cap ledge, this will then hold it on tight.
They are normally extremely close to the inlet plenum, especiually the bolt and are a pain to get on/off, they hit the corner as you struggle to take them off or put them on.
tabetha