FL2021 Motorcraft Oil Filter ?

[LS 2006]

According to the Summit Racing website, the FL2021 Motorcraft oil filter does not have an Anti-Drainback Valve.

Can anyone verify that?

Would no anti-drainback valve cause the engine to make a knocking noise on cold startup?

 

[joegr]

AFAIK, that is correct. I see a bypass valve in the bottom of the filter, but no check valve.

That's not your problem. I been through quite a few of the FL2021s on my LS's, and I've never had any knocking noises. Are you using the specified oil (5W20 semi-synthetic oil or 0W20 full synthetic)?