Some sending units have the 1/4†vapor return line and some don’t. My 69 has it. Have read that cars with 4bbls had it, or was it a production year thing? Do your 67s and 68s have it? And, if you do have it do you need a vented gas cap?
The 69 has the gas tank vented through a nipple braised to the neck of the fill pipe and then you usea non vented cap . Because of where the gas fill neck is if you used a vented cap every time you accelerated gas will spew out the vented cap.
Wade, that's odd because my 69 350 2bbl 4sp didn't come with a return line. None in the sender and none on the fuel pump. I just assumed that base 350s w/o AC didn't have them. Mine as an early build.
Wade, that's odd because my 69 350 2bbl 4sp didn't come with a return line. None in the sender and none on the fuel pump. I just assumed that base 350s w/o AC didn't have them. Mine as an early build.
I forgot to say mine was an A/C car and also has the nipple on the filler neck for the vent. That might be why
Ok. That makes more sense then because it was my understanding that the return line was included on the 400s and ac cars. Probably the HO cars as well. Could be in 69 only the 2bbl cars and the base ohc6 cars w/o AC came with no return line. I wonder if all 4bbl cars came with the return line. Ooooooo, that sounds like it makes mine all that much more rare! Probably 1 of only 67,000 or so builds. Lol.
My 69 was originally an HO 350 w/manual trans and no AC. It has the 1/4†return line. The filler neck vent was not intact or had been deleted. The reproduction tank has no vent in the neck. Will the return line act as a vent, or to be safe should I use a vented cap to prevent damage to the naw tank from “oil canning†due to exessive vacuum?
I think you're going to need a vented cap. Seems that they deleted the vent in the neck mid year on 69s( at least that's what I remember hearing). I think they used a vented cap after that, return line or not.
Thanks Robert, do you know how the vent was deleted? Mine still had the nipple on the neck but it was plugged. I always assumed that a previous owner just crammed something into it. It did have a non vented cap when I got it. ???
The 69 has the gas tank vented through a nipple braised to the neck of the fill pipe and then you usea non vented cap . Because of where the gas fill neck is if you used a vented cap every time you accelerated gas will spew out the vented cap.
JamesM has it correct for venting. As Harold states, "vapor return", is another way to call he return line because tha's what the return is there for. You will never get vapor lock again. I would recommend putting it in no matter what the size engine you have in it. If you ever upgrade to 4bbl or bigger engine it's there ready for you.
x3 Do not put vented cap on 69 tank.
Engine Test Stand Playlist: https://www.youtube.com/playlist?list=PLwoxyUwptUcdqEb-o2ArqyiUaHW0G_C88 restoring my 1968 Firebird 400 HO convertible (Firedawg) 1965 Pontiac Catalina Safari Wagon 389 TriPower (Catwagon) 1999 JD AWS LX Lawn tractor 17hp (my daily driver) 2006 Sequoia 2017 Murano (wife's car) 202? Electric car 203? 68 Firebird /w electric engine 2007 Bayliner 175 runabout /w 3.0L Mercuiser__________________________________________________________
I’m assuming that like so many of the repro parts that are advertised (many incorrectly) for “Firebird-Camaro†that the repro tank is aimed at the Camaro. If so, what did the Camaro use? Or did they have the vent, or vented cap? Also, it seems like the hole in the vented cap is so tiny that not much gas could escape.?? Could that be the case? Does gas escape out the neck vent tube under hard acceleration? Still not sure which way to go.
I’m assuming that like so many of the repro parts that are advertised (many incorrectly) for “Firebird-Camaro†that the repro tank is aimed at the Camaro. If so, what did the Camaro use? Or did they have the vent, or vented cap? Also, it seems like the hole in the vented cap is so tiny that not much gas could escape.?? Could that be the case? Does gas escape out the neck vent tube under hard acceleration? Still not sure which way to go.
I recall some time ago someone did have that issue. Try looking harder for a OEM or NOS tank. I got a NOS tank for my bird and my Catalina.
Engine Test Stand Playlist: https://www.youtube.com/playlist?list=PLwoxyUwptUcdqEb-o2ArqyiUaHW0G_C88 restoring my 1968 Firebird 400 HO convertible (Firedawg) 1965 Pontiac Catalina Safari Wagon 389 TriPower (Catwagon) 1999 JD AWS LX Lawn tractor 17hp (my daily driver) 2006 Sequoia 2017 Murano (wife's car) 202? Electric car 203? 68 Firebird /w electric engine 2007 Bayliner 175 runabout /w 3.0L Mercuiser__________________________________________________________
Good question. I never thought to ask how the camaros were arranged. I'm not exactly sure what Pontiac did after they did away with the vent tube in the neck either. They must've fixed it somehow. Maybe go to an aftermarket tank maker and ask how they control venting.
I’m assuming that like so many of the repro parts that are advertised (many incorrectly) for “Firebird-Camaro†that the repro tank is aimed at the Camaro. If so, what did the Camaro use? Or did they have the vent, or vented cap? Also, it seems like the hole in the vented cap is so tiny that not much gas could escape.?? Could that be the case? Does gas escape out the neck vent tube under hard acceleration? Still not sure which way to go.
Thank you all for your replies. Have given some thought to this, and for originalities sake, I think I’ll install the vent nipple into the filler neck (already have an aftermarket tank as the original was damaged). However the picture JamesM put up seems to show it in a different location than my original tank. If looking from the rear, the nipple on my original has it at about the ten o’clock position. Looks like it’ll line up good with the tube to the trunk from there. What do other 69s have?
I bought mine in 1978 and I’m sure it is the original tank and has never been out of the car but with all these cars it may depend on if it was done on a Friday or a Monday or what plant it was built at . Or beginning of the model year or the end because the 69 was a one year wonder it's hard to say.