New Fuel Injector Inserts (77 CIS), do I have to stake them into the runners?
 

I just put them in with a 10mm socket and an extension and some thwacking. They seem like they aren't going ANYWHERE. Do I definitely have to stake them or ?

I used a clicker center punch, easy, peasyhttp://forums.pelicanparts.com/support/smileys/wat.gif

Okay, I will do that.

I didn't stake mine. No issues for 9k miles. Just removed the CIS and nothing had pulled. I'd probably stake them now though in retrospect.

Since sometimes these hard plastic liners come out when all you want to do is pull the injector, it makes sense to stake, which isn't hard. You wouldn't want to glue them, so to speak, because they can get brittle and bits break off when pulling injectors, so they need to be pretty easy to remove as needed. The fat injector O ring exerts a lot more grip on the liner than the thin seal for the liner does to the manifold, so I'd expect if you pulled an unstaked injector the liner would come with it. Nothing someone prepared for this can't deal with easily, especially if you expect it. I try always to have a couple of new liners and their seals handy any time I pull an injector, just in case.

Unlike piston oil squirters (also staked), there is only the reaction to the constant flow of fuel to try to push them out on their own, and I guess that isn't at all like EFI (where there are stout structures holding those injectors in place). Interesting that you replaced the inserts but didn't stake, and all has been well. Good to know.

Do you have to? No


LOL, staking is another Model T technology that lived on at Porsche, much like wood floorboards, cardboard body parts, and tin wrapped exhaust passing as a heater.