What to do with leftover ports on the gas tank???

[Chevelle LT1]

In my quest to (finally) get my project car finished and on the road, I am running into one more road block: On the fuel tank, I have two unused ports on the fuel tank; one looks to be 1/4" and the other 1/2". For obvious reasons, I am trying to avoid having any open ports on the fuel tank, and would like to plug these. That being said, I have not yet come up with a clean way to plug these ports, and wanted to know what others may have done in the past. For what it's worth, the specs on the car are as follows:
- 1970 Chevelle
- Rock Valley Fuel Tank (original style)
- Vented fuel cap
- '94 LT1 motor

Any feedback/suggestions for what does (or does not) work is greatly appreciated.

Thanks.

~ Jason

[CarlC]

What kind of ports are they? NPT? AN? Holes?

[Hammered]

The 1/4" one is probably the vent. If it's just a tube, cap it off with a swage fitting, but make sure you have an alternative vent.

[DeltaT]

I would get rid of the vented cap and put a vertical loop (to prevent fuel spurting out of the filter) of 1/2" hose out to a filter someplace at the rear of the car. Cap off any others.

Jim

[Hammered]

Missed the vented fuel cap. Most vented caps let air in, but not out. You need a two-way vent with an EFI car. You can buy sintered metal breathers from McMaster Carr that thread onto the end of a tube.

[Chevelle LT1]

Thanks for the replies, and the suggestions. Can someone please explain to me why you need a non-vented cap, or is it just that you need the 2-way vent, which you can't get with the fuel cap?

Thanks again.

[DeltaT]

You need a 2-way vent. This was driven home to me when Fuel Safe screwed up and put a spring-loaded (1-way, in only) check valve in my fuel cell, and I was having early fuel heating and expansion problems and one day found the walls of my cell bulging with trapped pressure.

You want a angle-activated check valve (tipover protection) but you must have 2-way venting.

Jim

Here's the pic with the loop. It goes out through a bulkhead fitting to a small K&N filter:
https://static1.pt-content.com/images/pt/2009/01/4dr_reartrunkshot_090705_mini-1.jpg

[Chevelle LT1]

Sorry to dredge this up again, but in regards to the 2-way vents, can someone please provide some direction as to which to get? McMaster Carr was mentioned as a possible source, but after doing some digging on their site, I can't find anything that is obvious for working. Thanks again for the help.

~ Jason

[Hammered]

Look at their breather vents on pg 345 of the online catalogue. I'm using one on the end of a 5/16" OD SS tube turned upward and above the top of the tank. I stole the idea after seeing some race cars with the same setup.

[DeltaT]

Also check Summit, search for 'tipover valve' and you get 8 choices.

Jim