Fuel Tank Selection
Safety Car
Joined: Mar 2003
Posts: 3,583
Likes: 504
From: Indianapolis IN
Finalist 2020 C4 of the Year - Unmodified
C4 of Year Finalist (stock) 2019
The filler neck and tank venting is entirely different. 73-74 used a fuel seperator that attached to the upper lh corner of the tank which provided tank venting, and they also used non-vented filler caps
You should be able to used the 73-74 tank on you car if you get the correct parts. The supporting crossmember should be the same but you will probably need to replace your tank straps with the 18 gallon straps, as well as the filler neck, cap, and fuel seperator (kinda hard to find).
I bought my tank new from someone who advertised here on the board for $139.00 (new, made by American Designers) and it's great! I'ts a terriffic replacement...not NCRS (missing the AOL stamp) but perfect for a driver and exact in every other way.
You should be able to used the 73-74 tank on you car if you get the correct parts. The supporting crossmember should be the same but you will probably need to replace your tank straps with the 18 gallon straps, as well as the filler neck, cap, and fuel seperator (kinda hard to find).
I bought my tank new from someone who advertised here on the board for $139.00 (new, made by American Designers) and it's great! I'ts a terriffic replacement...not NCRS (missing the AOL stamp) but perfect for a driver and exact in every other way.
Le Mans Master
Joined: Jun 2002
Posts: 8,339
Likes: 24
From: I can walk to MA
Much discussion has revolved around tank capacity.
I don't think any were spec'ed at 14 gallons.
The 75 tank has a rubber bladder inside. it can often crack and trap fuel between the bladder and wall - effectively shrinking tank capacity.
The fix (since they don't make the bladders) is to buy the "75"
tank that Quanta has, pull the bladder from the old tank, cut off
the top most portion of the bladder, and use that to seal the sending unit against the top of the new tank.
Website says approximately 20 gallons.
http://www.quantaproducts.com/store/...em=13&mitem=13
Picture here:
http://gastanks.com/new_products.htm
I don't think any were spec'ed at 14 gallons.
The 75 tank has a rubber bladder inside. it can often crack and trap fuel between the bladder and wall - effectively shrinking tank capacity.
The fix (since they don't make the bladders) is to buy the "75"
tank that Quanta has, pull the bladder from the old tank, cut off
the top most portion of the bladder, and use that to seal the sending unit against the top of the new tank.
Website says approximately 20 gallons.
http://www.quantaproducts.com/store/...em=13&mitem=13
Picture here:
http://gastanks.com/new_products.htm
Le Mans Master
Joined: Dec 2003
Posts: 5,727
Likes: 38
From: Fremont CA
Actually the bladder is a GREAT saftey feature. The fuel cell is the same design as NASCAR racers use and Fuel Safe in Oregon makes replacement bladders for the late Corvettes. I would want the bladder in my Vette if some "bonehead" rear ended me at 25+MPH someday. The price is a little expensive! here is the link:
http://www.ioportracing.com/Merchant...tegory_Code=SA
http://www.ioportracing.com/Merchant...tegory_Code=SA
Le Mans Master
Joined: Apr 2000
Posts: 7,562
Likes: 9
From: B'Ville NY
Cruise-In III Veteran
St. Jude Donor '05
What's the difference between the one above and this one, besides $600 
http://www.ioportracing.com/Merchant2/merchant.mv?
http://www.ioportracing.com/Merchant2/merchant.mv?
Thread Starter
Instructor
Joined: Apr 2000
Posts: 165
Likes: 0
From: Vacaville California
NHvette,
Sorry; you're right: the '75 and '74 tanks are both listed at 18 gallons. It seemed I only got about 14 gallons out of mine: probably bladder issues, it sounds like.
Nobody makes a '75 bladder; my old one is gone. So is it possible to use a new '75 tank and just skip the bladder? Would a '63-'69 model tank fit, as they are listed as 20 gallons?
73L48Dave: You mention the '73-4 tanks used a fuel seperator gizmo on top of the tank to assist in venting. Do you know if these cars had the vent line running up to the charcoal canister, or was that eliminated since the tank had a vent on it?
Thanks, everyone!!
Patricia
Sorry; you're right: the '75 and '74 tanks are both listed at 18 gallons. It seemed I only got about 14 gallons out of mine: probably bladder issues, it sounds like.
Nobody makes a '75 bladder; my old one is gone. So is it possible to use a new '75 tank and just skip the bladder? Would a '63-'69 model tank fit, as they are listed as 20 gallons?
73L48Dave: You mention the '73-4 tanks used a fuel seperator gizmo on top of the tank to assist in venting. Do you know if these cars had the vent line running up to the charcoal canister, or was that eliminated since the tank had a vent on it?
Thanks, everyone!!
Patricia
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Le Mans Master
Joined: Jun 2002
Posts: 8,339
Likes: 24
From: I can walk to MA
Patricia, They are almost totally different.
The tanks for 68-74 (and earlier, too), while similar in size and
shape to the 75-77 tanks, are different. 68-74 fits like
73L48Dave says. The fuel separator is at the vent opening and
runs to the charcoal canister. The extra parts are gonna kill
you. I'd just get the 75-77 replacement without the bladder.
It's not worth all the trouble and cost for 2 gallons.
There was a post here a few weeks back that discussed the
inaccuracies of the sending unit/float. People would see they
are on 'empty' and 'filled up' with about 14 gallons - not
knowing there were a few gallons left.
The tanks for 68-74 (and earlier, too), while similar in size and
shape to the 75-77 tanks, are different. 68-74 fits like
73L48Dave says. The fuel separator is at the vent opening and
runs to the charcoal canister. The extra parts are gonna kill
you. I'd just get the 75-77 replacement without the bladder.
It's not worth all the trouble and cost for 2 gallons.
There was a post here a few weeks back that discussed the
inaccuracies of the sending unit/float. People would see they
are on 'empty' and 'filled up' with about 14 gallons - not
knowing there were a few gallons left.
Thread Starter
Instructor
Joined: Apr 2000
Posts: 165
Likes: 0
From: Vacaville California
NHVette-thanks for your help. Actually, I ran clean out of gas one time and when I went to fill it back up could only fit just under 14 gallons into the tank. It sure sounds like the bladder may have been cracked.
So the deal is I threw away tank (with bladder), tank support, etc. There was horrific rust back there. So I need to replace everything. Actually, I saved the fuel pick-up, but I'm wondering the sense in re-installing an ancient pick-up: do they tend to go bad? I'd hate to have to get back in there to change it, thus I'm considering replacing now, while it's easy.
Looking through Dr. Rebuild, etc., '75 pick-ups are terribly expensive compared to earlier years, no filler neck seal available, etc. Earlier years (such as 70-74) have everyting available for less $. I would LOVE the extra volume of the '63-'69 tanks, but I do not know if they will fit right up there?
So the deal is I threw away tank (with bladder), tank support, etc. There was horrific rust back there. So I need to replace everything. Actually, I saved the fuel pick-up, but I'm wondering the sense in re-installing an ancient pick-up: do they tend to go bad? I'd hate to have to get back in there to change it, thus I'm considering replacing now, while it's easy.
Looking through Dr. Rebuild, etc., '75 pick-ups are terribly expensive compared to earlier years, no filler neck seal available, etc. Earlier years (such as 70-74) have everyting available for less $. I would LOVE the extra volume of the '63-'69 tanks, but I do not know if they will fit right up there?
Safety Car
Joined: Mar 2003
Posts: 3,583
Likes: 504
From: Indianapolis IN
Finalist 2020 C4 of the Year - Unmodified
C4 of Year Finalist (stock) 2019
Originally Posted by singedfur
73L48Dave: You mention the '73-4 tanks used a fuel seperator gizmo on top of the tank to assist in venting. Do you know if these cars had the vent line running up to the charcoal canister, or was that eliminated since the tank had a vent on it?
Yes, the vent line from the fuel seperator connects to a steel vent line which runs up the LH frame rail to the charcoal canister. That is how the tanks were vented. The fuel seperator does just what it's name says, it seperates the fuel from the fumes...vents the fumes to the canister and routes the fuel back to the tank. Hope this helps!
I replaced all of the fuel delivery/return/venting components on my 73 during that phase of the body-off, frame-up resto. I know the system well
Dave
Last edited by Red86Z51; Nov 12, 2004 at 04:34 PM.
Le Mans Master
Joined: Jun 2002
Posts: 8,339
Likes: 24
From: I can walk to MA
You threw the tank and bladder away. Well, that's bad news for
using the 20 gallon replacement.
Yup - $225 for the sending unit stinks. $90 for the early style
still ain't cheap, but much easier to swallow.
If you want to run the EEC (with charcoal canister venting), then
the fuel separator is needed to convert to the earlier style tank.
Try searching for one of these before deciding to go that route.
If you go with an unvented version, you save the hassle and money of
the separator, but then you need to use a vented gas cap ('69).
This works fine, but the vented cap can cause gasoline odor problems.
If you park in an under-house garage - this could be an issue (not fire - just smell).
The flat answer is YES - you can put a '69 or '70 tank in place
of yours.
I have a 70 tank that I am currently restoring. I also have a 75
donor car in teh driveway with the tank sitting loosly. I'll try
and take a look at them this weekend and see if there are any
obvious problems that have not been mentioned.
It's snowing now, so don't hold your breath. I might not be able
to look at it right away.
using the 20 gallon replacement.
Yup - $225 for the sending unit stinks. $90 for the early style
still ain't cheap, but much easier to swallow.
If you want to run the EEC (with charcoal canister venting), then
the fuel separator is needed to convert to the earlier style tank.
Try searching for one of these before deciding to go that route.
If you go with an unvented version, you save the hassle and money of
the separator, but then you need to use a vented gas cap ('69).
This works fine, but the vented cap can cause gasoline odor problems.
If you park in an under-house garage - this could be an issue (not fire - just smell).
The flat answer is YES - you can put a '69 or '70 tank in place
of yours.
I have a 70 tank that I am currently restoring. I also have a 75
donor car in teh driveway with the tank sitting loosly. I'll try
and take a look at them this weekend and see if there are any
obvious problems that have not been mentioned.
It's snowing now, so don't hold your breath. I might not be able
to look at it right away.
Last edited by NHvette; Nov 12, 2004 at 05:56 PM.