I'm converting to E85, in high humidity So Fla, road race, EFI 600hp. I'm adding a desiccant trap by ATL in the fuel cell vent line.
The trap arrived today, and has push on, 1/4" NP x 5/16" barb fittings.
I can't see how that will properly vent E85 in my application or many others.
My fuel cell rollover vent is a #8 that I am connecting to.
I might be able to drill out/retap the trap for #8 fittings, not sure, ATL does not offer a larger fitting solution.
Do I have a potential problem here or am I missing something?

Jeez, JCC I thought you knew everything already, WHATS UP

I know it sounds crazy but could you cobble together a vacuum gauge in the vent line before the ATL desiccant trap? My tank vent is -8 hardline and I always thought that was kinda big. Maybe you run two ATL's in parallel?

I guess we are both "crazy", I was thinking same thing last night and that might be an interesting discovery into what is actually happening, and surprised there is so little shared experience on the subject, in that everybody is often an expert on fuel line sizing, but adequate venting and avoidance of ANY negative fuel cell pressure is overlooked?

I'll rig up a gauge to see what is going on, but it might be for naught, as I examined the inside the cell aspects of the ATL #8 rollover vent, I was shocked in that it has only two maybe 1/8" dia venting holes. That was surprising.

Before I'll run two parallel traps which is certainly a solution, I'll up-size the existing fittings and test.

5/16 line is big enough for an air vent. You only need about a gallon a minute of air. So less than 0.15 CFM.