Fuel lines, Gas Tanks, rear diffs, and radiators-1972 Challenger

[boxfox]

I just stumbled upon these forums today and figured this might be a good place to get some questions answered, which I have a lot of.
I don't want to ask too much all at once but I'll start with Fuel Lines and Gas tanks.

I have a 1972 Challenger, 440 engine from 1977, but was originally a 318.

I'm getting to changing out some of the old stuff left over from the 318, I heard moving the fuel lines up from a 5/16 to 3/8 would be an improvement.
Is this something worth doing or not?

I'm thinking of changing the fuel sending unit and the fuel lines, what confuses me is the vapor line. I understand there is the vapor separator, I have four lines hooked up into that running into my gas tank then it turns into one line that runs all the way up to my engine bay which ends up being a snipped line floating around near the bottom of the engine bay.
What is it doing there and why do I need it, if I need it can I have it somewhere else?

And onto gas tanks, mine is rusty around the edges has a patch repair spot, I figure I should just replace it.
I saw some decent looking ones on ebay for around 170 in total with shipping, but I cannot find gas filler necks ANYWHERE.
Am I blind or where can I find them?

My rear differential is another thing I want to improve, I currently have a 8 3/4 axle , 489 case, and 2.76 gears.
Sure-grip means both tires will turn during a burn out and I won't have tire hop in the corners correct?
I still want to retain highway and cruise-ability in the car so I was thinking of maybe a 3.23 sure-grip.
When I get the new gears, does the case have to be the same or do I need a 742 or 741 or can I stay with the 489 or does it usually just come all together?

Radiators...
I'm assuming my radiator is left over from the 318, its 26 inchs wide and has rust floating around in it.
The 440 is running at about 215-220 degrees F, is this normal or unhealthy? should I just get a stock replacement or is there something better I can get that won't break the bank.

I know I'm asking a lot of questions but I thank you if you've taken the time to read all of this and or reply to it.
I'm a beginner to Mopar, this is my first one, anything you can say will help me greatly.

[Bullitt-]

Welcome boxfox.... Lotta questions for one post but none I have not seen before...
  If your changing your fuel lines go to the larger if not the 5/16 are adequate unless your very HP.
Vapor line is useless without the charcoal canister which is usually gone...can be used with a special fuel filter as a return line to prevent vapor lock. The 3/8 sending unit has provisions for this on the tank end. All New gas tanks are from the same manufacturer so get the best deal you can, no one reproduces filler necks so fix what you have or seek a better used one.
  3.23 sure grip will fit your rear end case
 If the lower radiator hose is on the drivers side you for sure have a big block radiator, small block & some later big blocks are on the passenger side....All relative if it keeps you cool, if not something needs to improve, When does it run hot, in traffic or at speed? 215 is not that bad.
 


 

[boxfox]

It runs around 215-220 degrees all the time.

What is this special filter you mentioned?
So I need to do something to prevent vapor lock?
Why can't the vapor line just stay near the back of the car, does it need to be up front?

[Bullitt-]

OOPS Maybe not a filter, a vapor separator
http://chucker54.stores.yahoo.net/vase.html

Don't have to have it but it keeps the fumes enclosed...
 

[Bullitt-]

It runs around 215-220 degrees all the time.

Have you checked the accuracy of your instruments?...Usually a cooling problem will be one of two things....to much heat being created or not enough cooling capacity,  To Much heat manifests as overheating while driving hard( to much advance, lean mixture) or  not enough cooling capacity due to undersized or inefficient radiator or fans/air flow show up more when sitting in traffic.

[brads70]

OOPS Maybe not a filter, a vapor separator
http://chucker54.stores.yahoo.net/vase.html

Don't have to have it but it keeps the fumes enclosed...

Hey Wade, I'm missing this too. how would I plumb this to the carb? Tee into the PCV valve? where is the correct place to mount it?

[Bullitt-]

Hey Wade, I'm missing this too. how would I plumb this to the carb? Tee into the PCV valve? where is the correct place to mount it?

Best I can tell it goes on the fuel line & the extra nipple goes back to the tank...Seen this discussed before in regards to vapor lock ..
 We need to let a big block guy cover the details. 

[BIGSHCLUNK]

Brad, my 70 dosent have any seperator... 

[boxfox]

The lower hose is on the driver side so I suppose the radiator is for a big block.
The accuracy of the instrument...the instrument is a crappy like 20 dollar temperature gauge.. so I dunno about accuracy. The car never over heats or anything I was just wondering if that is a normal temperature or not.
So should I be fine running it like this in the summer?

What if I don't want to deal with getting a filter..(Seems a bit expensive)
can I just take the hose of the top of this unit pictured.

I'm gonna use burdar's picture from a previous thread..Hopefully he doesn't mind.


What are the 4 nipples even for? I noticed they all hook to the gas tank and the top one seems to be the vapor line that simply runs up to my engine bay and is sitting there...so is it releasing any gases or just letting air in? Would it be alright to just leave the top open without a hose on it if all its going to do is let air into the gas tank?

[Bullitt-]

There are 4-corresponding nipples on the gas tank...the other end is what's missing...the charcoal canister...All this is Pollution BS....doe's not hurt anything but if your not doing a resto you don't need to worry about it, just makes an easy way to vent your tank if you have all the stuff....Like you suggested can just connect a hose to the top nipple & let it vent to the air, only thing is if your cars inside you will smell that old gas odor. 


Here's a pic of a  '73s canister,  '72s did not have the big hose in the middle

[Bullitt-]

The accuracy of the instrument...the instrument is a crappy like 20 dollar temperature gauge.. so I dunno about accuracy. The car never over heats or anything I was just wondering if that is a normal temperature or not.
So should I be fine running it like this in the summer?

 All I've read here 220 is top of Normal range. Take it a few steps at a time & see what happens, find someone with a laser thermometer & check around the intake to see what the actual temps are.... Seen a few folks chasing problems just to find out the gauge was way off.

[brads70]

Boxfox, hope you don't mind me asking questions on your thread?
Wade, I have 1 hose in the engine compartment that goes to the rear of the car.Where/what does this hook to? Mine is a 70 from CA so it has that dohicky in the trunk.

[BIGSHCLUNK]

Aaahhh Cally car, now I get it 

[Bullitt-]

All I've ever seen on a '70 is the nipple at the top of the filler tube, don't know if that's the CA setup or not...Some have an extra tube inside the trunk, similar to the filler tube, that has something to do with emissions but I'm not up to speed on what that's all about. 
  Brad, sorry I don't know everything 

[Bullitt-]

Aaahhh Cally car, now I get it 

Bigs your vert has a vent deal in the trunk if I recall...how does that work?