Beelzeboss
Well-known member
I've recently had to put a rollover valve in my hot rod so I thought I'd put together a thread showing how I did it.
Start with a cheap check valve / one-way valve that can be disassembled, like this one:
Unscrew it to reveal the inside.
From left to right we have:
The outer shell
The spring guide
The spring
The seal
The inner shell
What we want to do is remove everything from inside, except for the seal between the two shells, and replace it with a single ball bearing.
One of the shell halves should have a tapered seat. On this end we want to make a sealing surface for the ball bearing. The easiest way to do this is to put the shell in a vice, place the ball bearing in, then use a hammer and drift to give it one solid whack. This creates a seat exactly matching the ball bearing which should seal perfectly. This ball-seat seal should prevent fuel from coming out of the vent in the event it goes upside down.
On the other shell we need to make sure that the ball doesn't seal on that surface when the car is the right way up. I used a small triangular file to put a few notches into the would be seat, but a Dremel would probably work better. They don't need to be deep but the bigger/more scores you put in the seat the more it will be able to vent in normal operation.
Then clean it up and screw it back together with the ball bearing inside. Make sure to install it so in normal operation the ball bearing will sit on the seat with the notches; the sealing seat should be above the ball.
Start with a cheap check valve / one-way valve that can be disassembled, like this one:
Unscrew it to reveal the inside.
From left to right we have:
The outer shell
The spring guide
The spring
The seal
The inner shell
What we want to do is remove everything from inside, except for the seal between the two shells, and replace it with a single ball bearing.
One of the shell halves should have a tapered seat. On this end we want to make a sealing surface for the ball bearing. The easiest way to do this is to put the shell in a vice, place the ball bearing in, then use a hammer and drift to give it one solid whack. This creates a seat exactly matching the ball bearing which should seal perfectly. This ball-seat seal should prevent fuel from coming out of the vent in the event it goes upside down.
On the other shell we need to make sure that the ball doesn't seal on that surface when the car is the right way up. I used a small triangular file to put a few notches into the would be seat, but a Dremel would probably work better. They don't need to be deep but the bigger/more scores you put in the seat the more it will be able to vent in normal operation.
Then clean it up and screw it back together with the ball bearing inside. Make sure to install it so in normal operation the ball bearing will sit on the seat with the notches; the sealing seat should be above the ball.