#1  
Old 10-27-2024, 08:08 PM
punkin punkin is offline
Senior Chief
 
Join Date: Aug 2016
Location: Northern Colorado
Posts: 316
Default First Gen F-body Fuel Tank Vent

Hello all,

Initially I posted in the 67-69 Firebird section thinking my question was a bit more vechicle specific but I haven't had any responses yet. Apologies for the double postings.

I have a 68 firebird. Purchased a Rick's tank for EFI and have installed a Sniper Xflow efi system. I was hoping that the vented gas cap would be sufficient to vent the tank but it's only a one-way vent as far as I can tell.

I have an extra port on the top of the tank for a vent line. Everything I've read is that the vent line should be at least as high or higher than the fill port. I've read in some other forums where guys are running vents up high inside the trunk but I'm not convinced this is a good idea.

I'm open to suggestions and if you're using a vent with a check ball or baffle of some kind I would really like to know what you're using.

Thanks very much for taking the time to read through this.

__________________
1968 Firebird
IAIIa 522
340 E-heads
Northwind with XFlow TBI
4L80E
3.50:1 Rear

1969 Firebird
350/TH350
Mostly stock
2.56:1 Rear
  #2  
Old 10-27-2024, 08:12 PM
tom s tom s is offline
Ultimate Warrior
 
Join Date: Jan 2000
Location: long beach ca usa
Posts: 19,032
Default

The cap vents in but not out.I drilled a small hole in my cap I use when the car sits but if I drive with it fuel leaks out.Tom

  #3  
Old 10-28-2024, 10:40 AM
JLMounce JLMounce is offline
Ultimate Warrior
 
Join Date: Sep 2005
Location: Greeley, Colorado
Posts: 3,938
Send a message via AIM to JLMounce
Default

I use the vents on my Tanks Inc tank (1 on the tank, 1 on the pump hat) and tie into the factory vent that is indeed above the fill port. I have not had any issues with this setup.

__________________
-Jason
1969 Pontiac Firebird
The Following User Says Thank You to JLMounce For This Useful Post:
  #4  
Old 10-28-2024, 06:14 PM
krisr's Avatar
krisr krisr is offline
Ultimate Warrior
 
Join Date: Sep 2003
Location: Sydney, OZ
Posts: 1,462
Default

You can run the vent line up above the rear end and coil the line a few times then point it back down. If the vent line is up the front of the tank the only time it "may" get fuel go into the line is when you're hard on the brakes

__________________
'71 Holden HQ Monaro - 3850lbs race weight, 400c/i - 11.4 @ 120
'66 Pontiac GTO - 389, 4 speed street cruiser
  #5  
Old 10-28-2024, 07:25 PM
punkin punkin is offline
Senior Chief
 
Join Date: Aug 2016
Location: Northern Colorado
Posts: 316
Default

Quote:
Originally Posted by JLMounce View Post
I use the vents on my Tanks Inc tank (1 on the tank, 1 on the pump hat) and tie into the factory vent that is indeed above the fill port. I have not had any issues with this setup.
Thanks Jason, if I'm not mistaken, the 69 has a vent tube built into the filler neck doesn't it? Is that where you're taking yours? If so, unfortunately, the 68 doesn't have this. I've heard of guys welding or brazing in an additional tube into the filler neck. I'm toying with that idea as well.

__________________
1968 Firebird
IAIIa 522
340 E-heads
Northwind with XFlow TBI
4L80E
3.50:1 Rear

1969 Firebird
350/TH350
Mostly stock
2.56:1 Rear
  #6  
Old 10-28-2024, 07:26 PM
punkin punkin is offline
Senior Chief
 
Join Date: Aug 2016
Location: Northern Colorado
Posts: 316
Default

Quote:
Originally Posted by krisr View Post
You can run the vent line up above the rear end and coil the line a few times then point it back down. If the vent line is up the front of the tank the only time it "may" get fuel go into the line is when you're hard on the brakes
One thing I'm concerned about with the looping of line is if fuel does get up in there, wouldn't that create a vapor lock much like a p-trap in a sink drain and then defeat the vent? Maybe I'm not imagining what you're describing correctly.

__________________
1968 Firebird
IAIIa 522
340 E-heads
Northwind with XFlow TBI
4L80E
3.50:1 Rear

1969 Firebird
350/TH350
Mostly stock
2.56:1 Rear
  #7  
Old 10-28-2024, 09:10 PM
JLMounce JLMounce is offline
Ultimate Warrior
 
Join Date: Sep 2005
Location: Greeley, Colorado
Posts: 3,938
Send a message via AIM to JLMounce
Default

Quote:
Originally Posted by punkin View Post
Thanks Jason, if I'm not mistaken, the 69 has a vent tube built into the filler neck doesn't it? Is that where you're taking yours? If so, unfortunately, the 68 doesn't have this. I've heard of guys welding or brazing in an additional tube into the filler neck. I'm toying with that idea as well.
Ah yes I always forget the is a 69 option. Yes there was a vent in the filler neck that goes up and loops out near the top of the license plate.

Other things I've seen people do is get a rollover vent and mount it near the top of the axle or mounted to the underside of the trunk pan. It just needs to be higher than the top of the tank. The rollover vents are a good safety device and aren't too expensive.

__________________
-Jason
1969 Pontiac Firebird
The Following User Says Thank You to JLMounce For This Useful Post:
  #8  
Old 10-28-2024, 09:29 PM
punkin punkin is offline
Senior Chief
 
Join Date: Aug 2016
Location: Northern Colorado
Posts: 316
Default

I thank you.

__________________
1968 Firebird
IAIIa 522
340 E-heads
Northwind with XFlow TBI
4L80E
3.50:1 Rear

1969 Firebird
350/TH350
Mostly stock
2.56:1 Rear
  #9  
Old 10-28-2024, 09:34 PM
punkin punkin is offline
Senior Chief
 
Join Date: Aug 2016
Location: Northern Colorado
Posts: 316
Default

Quote:
Originally Posted by tom s View Post
The cap vents in but not out.I drilled a small hole in my cap I use when the car sits but if I drive with it fuel leaks out.Tom
Not to dismiss, in a pinch this could work but...I would like to avoid wiping the bumper down after a field trip. I've got a pretty steep drive-way too.

__________________
1968 Firebird
IAIIa 522
340 E-heads
Northwind with XFlow TBI
4L80E
3.50:1 Rear

1969 Firebird
350/TH350
Mostly stock
2.56:1 Rear
  #10  
Old 10-28-2024, 09:51 PM
tom s tom s is offline
Ultimate Warrior
 
Join Date: Jan 2000
Location: long beach ca usa
Posts: 19,032
Default

I have 2 caps,keep the one with a hole in a zip lock bag.Tom

The Following User Says Thank You to tom s For This Useful Post:
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


All times are GMT -4. The time now is 11:11 PM.

 

About Us

The PY Online Forums is the largest online gathering of Pontiac enthusiasts anywhere in the world. Founded in 1991, it was also the first online forum for people to gather and talk about their Pontiacs. Since then, it has become the mecca of Pontiac technical data and knowledge that no other place can surpass.

 




Copyright © 2017