Are these lower intake heated spring washers really needed or can standard washers be used: https://conceptzperformance.com/nis...ted-spring-washer-z32-14037-v5200_p_12635.php Buggered if I can find mine and I'm not that keen on spending over $100 on these if I can use something else.
I always assumed those were just solid spacers, but after looking closer at a few used ones I have here, they definitely are a multi-piece part... From an engineering point of view, it's not uncommon to use spring washers under bolt heads to mimic bolt stretch and preload the fastener to prevent it from vibrating out - the importance of that function here is debatable... maybe it's one of those redundant system safeguards since the timing idler is on the end of the lower plenum and its stability is critical to engine longevity? At the very least in lieu of these OE spring washers, a spacer that is the same thickness would be needed to be able to use the original bolts and prevent them from bottoming out.
I wouldn't be surprised if they're essential. You're bolting into aluminium and we all know common it is for the coilpack and balance tube bolts to be stripped out from overtorqueing. On top of that the thermal expansion of the head and plenum is something between 50-100% more than the expansion of the steel bolt so they probably couldn't get a torque spec for the fasteners that worked in all conditions without an expensive bandaid
