What is the biggest factory or (factory looking) aftermarket gas tank you can get in a C3. looking through chiltons book, which only goes to 77 it shows a 20 gallon tank,,,on a different forum a fellow with a 81 or an 82 said his has a 23.7 gallon tank. would an 82 fit in a 76 without any major work?

 

The way a '78-'82 "is sloped" behind the rear window accounts for on why these cars can have larger tanks. The way '68-'77s have the "flat deck" behind the window is the reason for the 20gal tanks. Also, I believe the fuel filler neck location is closer to the bumper on a '78-'82, than a '68-'77. I once had a '78 tank next to a '75 tank, but did'nt get a pic. Their width & length dimensions are virtually identical, it's the height & the "slope" which is the main difference between the two designs.

 

mine has a 13 gal tank,,,,,,,,,the person next door with a civic has a bigger tank than that :rolleyes: , with my new 496 going in i will need the biggest tank i can muster in there............what is the biggest tank that will fit in there without any major mods?

 

I'm puzzeled....how do you know it's a 13 gallon tank? All vettes have 20 gallon tanks and Paul mentioned the 78-82 have 23 gallons..

 

GDaina, incorrect sir, I"m not sure just WHY, but my '72 vert has a replacement tank by previous owner, with GM markings on it....parts label...and it's an 18 gallon tank.....which I think was standard for the chrome sharks anyway....what I need to know is if the '82 tank meant from the factory for a FI car, can be fitted into my car....I THINK the filler caps are in the same relative location measured from the rear of the car, so the only option I see is the tank is expanded further forward, thereby making the filler neck appear differant when compared......I hope I"m right anyway....
I would like to have a factory prepped NO BLADDER tank for the FI, tired of the problems with the fuel slosh, and even water accumulation....

GENE

 

I doubt you have a "13 gallon tank". You have a 20 gallon tank with a "collapsing" bladder(rubber liner)causing the tank to hold ONLY 13 gallons. Remove the bladder and you'll be back to 20 gallons. This is now fairly common to '75-'77 Corvettes which had this type of set-up, which all these years had.

 

I emptied out the tank once because i heard something rattle which drove me nuts,,,,,,,it was a curved piece that was welded to the bottom next to the float, the weld broke and it was just sliding around in there. the whole tank was metal on the inside,,,,,,,,,,and, when i filled it up from dead empty (minus the one gallon to get me to the gas station) it held 13 point something gallons. :confused:

 

Can this bladder be removed easily or do you just get a new tank. My 75 has never taken more than 10 gallons even when the gauge is reading very low.

 

This is not hard at all and involves dropping the spare, tire tub, plastic cover above tub, and the fuel tank.

What you need to do once the tank is on the ground facing up, remove that oval/rectangular shaped panel, which houses the sending unit & fuel pick-up. Carefully remove this panel because if the "bladder" has collapsed over your sending unit & pick-up you could damage either if you're not careful about doing it. The bladder "neck" simply makes the gasket between this panel just mentioned and the tank itself. Carefully with nice trimming scissors cut the bladder away and retain the part that makes this "gasket". It's about a three hour job and while you're doing it replace all the rubber lines back there and you'll be back to taking 20 gallons of fuel. My '75, which I bought in '90 and had 106K miles on it was happening to it back then. In 1994 it actually got to the point where part of the bladder was against the fuel door and I COULD'NT even put gasoline into it :eek: It was then I decided to drop the tank and see what I could do to "make it better". It's been this way since '94 and it's now set-up like any pre-'75 Corvette. Been great. Oh, by the way, if you're tank is rusty & crusty, Quanta now reproduces the metal shell or tank WITHOUT the bladder, so again, you'd be just like making it a '74 and earlier set-up. :yesnod:

 

On my 76, the bladder neck "gasket" also contained the captive inserts used to fasten the sending unit to the tank. I don't know if that is unique to my year or what. I cut the bladder below the hard plate portion containing the inserts. I thought long and hard before doing it - my bladder had not collapsed at all, and looked fine, but I chose a "pre-emptive strike" based on the number of problems posted here. BTW, the baffle had broken from my sending unit also, and needed to be spot welded back on. If you want any pics, let me know - I haven't yet reassembled and installed.

 

How badly do you want more capacity?

Swap the spare tire carrier for one from a C4 using the small wheel (there is a term for the small wheel, but I can't think of it). You will need to modify the crossmember the tank sits on, but you will gain another 41/2" to 5" of depth which will add another 10-12 gallons of capacity.

This mod is not, however, for beginners. Food for thought, maybe.
Spike

 

that might be a good idea spike :cheers: , i dont run the spare tire carrier anyway,,,,,,,is the 85 tank style close in design to the mid c3 tank?

I am building a nice little 454/496cid motor with a good bit of umph :hurray: ,,,,,and i love to take long drives in the mountains and to Canada,,,,,,,,the bigger the tank the better
whats the capacity on an 84 tank? :confused:


[Modified by Titanium Rat, 6:58 PM 10/18/2003]

 

i don't believe that. I have owned my 75 since 1980 and have NEVER put more than 14.8 gallons in it.

 

The words I think you were searching for is "temporary tire" or "doughnut". :thumbs:

 

i looked in my chiltons book and it shows only 3 tanks in a c3 up to a 1976 (the book only goes to a 76) a 20 gal for early c3's then an 18 and in 75 in dropped to a 13 :U (i guess for the better economy they didnt need a big tank)

 

13 gallon tank in a '75 Corvette??? :confused: Are you sure they did'nt mean C-H-E-"V-E-T-T-E" Remember those :confused:

Chilton's,Where America Gets It's Correct Corvette Information :lolg: :lolg: :lolg: