idler arm questions

The new components are always a little tight. Give it a bit to settle in and it should be fine.
An alignment is needed though. If nothing for some peace of mind.
As for the castle nut / cotter pin issue, you can use a washer between the nut and the center link to move the nut closer to the hole... but DO NOT use a washer between the arm and the center link...
I said you can, but that is up to you. Washers can break and fall out = instant steering play. If the nut starts to come loose you will get gradual play until it hits the cotter pin and stops... will either of those things happen? I've seen both, but only once each in 20 yrs
Mopardude318, I think he is worried that the nut can come undone by a couple of threads before the cotter pin will touch the top of the nut and keep it from turning.
Flyboy, Is that correct?