What I did was pull the plug connector. I then plugged a spare sparkplug to the end and arranged it against engine ground. This allowed me to verify spark AND prevent damage to the coil from excess HV generation. This would be more of a pain to do if disconnecting at the distributor. In addition, you might risk arc-over to another plugwire, which could confuse the issue and start a carbon path somewhere. On ours, I also find it easier to pull a plug connector than those tenacious boots on the distributor cap.

Steve

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'91 MB 190E 2.3
'08 RAV4 Ltd 3.5
'83 Lazy Daze m'home 5.7