I put my headers on last night and today I checked them and some were very loose and others had loosend up as well, is this normal. I got the stainless steel 12 point arp 3/8 head, header bolts, will I need to add a lock washer on them, or will they stop getting loose after a few heat cycles?

 

this happened to mine... had mac equal length ceramic coated headers and they kept getting loos but after a while of tightening every once and a while they stayed! lol just keep tightening them and they should eventually stay! lol that was my experience anyways

 

Cool, thanks for the input bud.

 

Yep, it's common practice to have to re-tighten them a few times, they'll hold eventually.