It looks to me like the Air Separator Tank Bypass mod is just a 2nd generation filler neck replacement and the 2nd generation filler neck looks to be a 3rd generation filler neck with a hole in the side of it... I ordered the AST bypass kit from M2 over two months ago and I'm getting a bit pissed. I'm definately going to cancel my order with them. I'm thinking of just drilling a hole in my current filler neck to make the mod. Is that an insane idea or would it work? I realize that this make be an outrageously stupid question. If so, feedback is welcome but I ask that you be gentle on the sarcasm. Thanks.
Mike

 

This is what I did and it is very inexpensive, if you look closely between the filler neck and the cap you will see a little riser that holds a nipple for the bypass.

Here are a couple of threads about ASTs and eliminating ASTs



https://www.rx7club.com/showthread.p...hreadid=130620

https://www.rx7club.com/showthread.p...threadid=30651

 

Thanks for the help. Can I drill a hole in the neck I currently have though? As I understand it, the nipple modification provides an escape route, so I was thinking that drilling a hole would do the same thing... Is that wrong?

 

Just make sure there is enough room below the seat for the cap, other wise you can't get the proper pressure build up. (unless you have a 0psi NPG+ system)

 

Why not just order the 2nd gen filler neck from the dealer? Might just take a couple days & will eliminate the questions. Would be even cheaper if you find one at a junkyard.

 

On the stock filler neck there isnt really a place for the pressure cap to seat. If you just drill it out no pressure will build so unless you run Evans NPG then you will need to get the 2nd gen filler neck. It cant be more than a couple bucks at the local wrecking yard.

 

I don't find that a supid question at all, I have done that and it's working very well for over a month going to 2 months now.

Drill the hole lowest possible on the neck and put a 3/8 copper pipe (make sure the hole is tight for the pipe) like 2 1/2" long, solder it and you set.

 

Thanks for all your help and advice fellas... I'm going to search locally before I start drilling anything!

 

Can I take out the AST completely after the bypass?