Replacement fuel tank questio

[Auston]

Hey guys. Ran into my first issue on the 71. I ordered a new spectra tank from rock auto. Everything fit great but my original tank had a fitting in the upper passenger corner whereas the new tank doesn’t. From what I found on here, that fitting is for the vapor line?? If thats correct, I’m assuming it’s no longer needed being as the new tank did not have it. Do I need to plug that off, leave it as is, or what? Thanks for the help.

[RustyPile]

My '71 has the same vent lines. Originally, that line carried the vapors to the vapor (charcoal) canister. Vacuum controlled valves on the canister vented those vapors back to the engine.. The tank you have is for a different venting system.. First, you'll need a way for it to vent or when the fuel pump pulls fuel from the tank, the vacuum created will make the pump unable to pump fuel and the engine will quit running (literally run out of fuel), leaving you stranded somewhere..

Others may not agree, or will offer other options, but I'm of the opinion that you have the wrong tank for your application.. This is the main reason I DO NOT patronize Rock Auto.. Return it and get the correct tank for your application.

[Auston]

Great. I can see how this project is going to go already. Had a 50/50 shot out getting it right and ordered the wrong one. Just my luck. Lol

However, I understand what you’re saying about the tank creating a vacuum and not being able to pump fuel. But, if the fuel cap is vented, wouldn’t that allow air to enter the tank when fuel is pumped out?

[RustyPile]

Originally Posted by Auston

Great. I can see how this project is going to go already. Had a 50/50 shot out getting it right and ordered the wrong one. Just my luck. Lol

However, I understand what you’re saying about the tank creating a vacuum and not being able to pump fuel. But, if the fuel cap is vented, wouldn’t that allow air to enter the tank when fuel is pumped out?

That's what I meant by "other options".. What you say is very true, but that's not how GM designed it to work.. Has to do with "cleaning up the air (emissions)".. Plus, the carburetor is calibrated to include those vapors in the combustion process...

I'm a retired mechanic having worked in the field for over 30 years. During that time, I received lots of GM (and many other mfgrs.) factory training, and people paid me good money for repairing their vehicles the correct way. I view these things different from your average do-it-yourselfer..

[Auston]

I’m also one that wants it fixed the way it was. I don’t like stuff just hanging or open hoses or anything. If it’s there, it has a purpose. With that being said, I’m ordering the correct tank. Thanks Rusty for the knowledge. I greatly appreciate it.

[Auston]

Originally Posted by RustyPile

That's what I meant by "other options".. What you say is very true, but that's not how GM designed it to work.. Has to do with "cleaning up the air (emissions)".. Plus, the carburetor is calibrated to include those vapors in the combustion process.

I enjoy learning the theory and concept of how this stuff works just as much as I love working on them. I by no means was questioning you, just wanted to see if my thought process was correct.

[RustyPile]

Originally Posted by Auston

I enjoy learning the theory and concept of how this stuff works just as much as I love working on them. I by no means was questioning you, just wanted to see if my thought process was correct.

Trust me, I took [edit] no offense at what you said.. I read in your other thread that you're a small engine mechanic.. I knew you'd understand my stance on customers expecting quality work... I read some of the methods used by some of these guys on their vehicles.. Then when some shop uses the same approach that same person's vehicle, they come unwound and want to set fire to that shop..

Auston, you've come to a good place here.. There are some very knowledgeable people on here and most are eager and willing to help you with any issues that you might "uncover" in that old truck you have.

[RustyPile]

Since you're already dealing with Rock Auto, I took the liberty of looking up the correct tank for your truck.. Here's a link to that tank.

https://www.rockauto.com/en/moreinfo...A73fvFtsSqeANb

It's made by Dorman, a line of parts that is available at most any local auto parts store -- Napa, O'Reillys, and most local "Mom & Pop" suppliers..

[Auston]

Originally Posted by RustyPile

Since you're already dealing with Rock Auto, I took the liberty of looking up the correct tank for your truck.. Here's a link to that tank.

https://www.rockauto.com/en/moreinfo...A73fvFtsSqeANb

It's made by Dorman, a line of parts that is available at most any local auto parts store -- Napa, O'Reillys, and most local "Mom & Pop" suppliers..

Thank you sir. I read somewhere that unless your truck was built in California, it wouldn’t have the emissions stuff. I knew that was somewhat of a joke, but thought for sure this truck wouldn’t have it. Guess that’s what I get for not doing my research

[RustyPile]

Originally Posted by Auston

Thank you sir. I read somewhere that unless your truck was built in California, it wouldn’t have the emissions stuff. I knew that was somewhat of a joke, but thought for sure this truck wouldn’t have it. Guess that’s what I get for not doing my research

That is somewhat true, but not always the case. Starting around 69 - 70, "tight" emission controls started showing up on passenger cars and some light trucks. California vehicles have always had the most stringent systems.. The other states requirements traditionally trail California by a couple years. For instance, I think the first year for PCV systems in California was around 1957.. That system didn't show up in other states until around 1962 - 63..

Just like in football, there are "armchair quarterbacks" on the internet.. With these old trucks there is much misinformation on the internet, but just because you read it there, doesn't make it true..

This is why for the most part, I don't go first to the internet when shopping for parts.. If I have doubts about a part, I take the old one with me and compare it to the new one..

[Auston]

Yeah I definitely know better than to assume that would be correct. Assuming has cost me a lot time and headache at work.