I recently picked up a set of the Delco Iridium plugs and promptly set the gap to .055- did not realize they were set to .040 when made .

I intend to install them this weekend so....

2 questions-

1. Odds of actually damaging them by re-setting the gap?
2. Shift them back to .040 or leave them at .055 (.040 seems awfully small for a NA motor)?

Thanks

 

I used the NGK iridiums, and I left them at .055, works fine for me on a basically stock motor. Be very careful if you do gap them, because it's VERY easy to break the electrode, I wound up having to go down and buy another $7 spark plug over the same thing.