gas tank sending unit from 75 vega

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gas tank sending unit from 75 vega

Postby chevyart » Tue Jul 27, 2021 1:49 pm

took my stock tank out, cleaned it and added a rear sump(done by chassis builder. thing i dont understand is that the distance from hole in top on tank to bottom is 5 1/4 inches and complete bottom of tank is flat. the sending unit i took measures 9 to 91/4 inches from sock to disc on top of sender unit where it gets sealed by rubber gasket and lock ring. this whole part of the pump is not flexible at all. my question is how does this long sending unit fit into the tank. that is only 5 1/4 inches deep? it just seems like an impossibility. its like putting 2 pounds in a 1 pound bag. can anyone explain this. Zeke has found some real good replacement sender units from spectre and said you may have to alter the length a little and make them shorter. i also am not using the intank fuel pump, just the sender unit. any input is appreciated. thanks Art
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Re: gas tank sending unit from 75 vega

Postby gt350fme » Tue Jul 27, 2021 9:19 pm

Picture of what you have would be helpful, we can help you modify what you have, for reference a pic of my modified sender with Stewart Warner sender works perfectly with aftermarket gauge, this would not work with stock gauge unfortunately.
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Re: gas tank sending unit from 75 vega

Postby gt350fme » Wed Jul 28, 2021 4:16 pm

If you are unable to post a picture of your sender, give us the part # and manufacture name, is it one of the spectre units?.
We can look that up and make a number of suggestions of how to modify, a number of members here have modified senders, I know we can do this and get you closer to finishing your car.
GT
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Re: gas tank sending unit from 75 vega

Postby chevyart » Wed Jul 28, 2021 5:25 pm

thanks gt350. i am not going to reuse the stock unit. it is shot. i am going to use the Spectre unit # FG05G. it is only the sender unit. i am using an electric pump out of the tank.. my tank measures exactly 5 14 inches from hole at top of tank to the flat bottom, and the bottom of my tank is completely flat. so i would need help in finding the final height to the bottom of my float to get me the desired reading on my stock fuel gauge of 0 when empty and 90 when tank is full.. i am pretty sure this sender will need to be shortened in 2 different places to get the desired height so as not to disturb the integrity of the sender part of the unit, thanks for any help . Art
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Re: gas tank sending unit from 75 vega

Postby gt350fme » Wed Jul 28, 2021 10:57 pm

Got it, I see couple of ways of modifying this as follows.
Since you are not using the fuel pipe, cap plug off at the top nipple and be done with that.
1. Cut the fuel pipe at the red line and be done with that, then carefully bend the fuel line blue line with tubing bender a little at a time more or less to get about that 5 inches you need so that the float is just hovering above the bottom, may also need be bend the float arm green line forward or back to make float hover 1/4 inch above tank bottom. ORRRRRRR
2. Instead of bending fuel pipe, second picture cut green line overlap by 1 inch or what it takes to raise hover the float just above bottom, hammer flatten the 2 overlaps, drill 2 holes for 2 screws securing overlap, ORRRRRRRR cut out section of fuel pipe green line and solder in a union or compression union to reconnect fuel pipe again hovering float just above bottom.

If you look carefully at my fuel sender float arm it is quite bent around and works as should.

P.S. a few extra thoughts, setting float at empty is one thing, float at full is another, I had to shorten my float arm as to not hit the tank top, yours may be short ? May be too long? I was able to inspect mine through the tank vent hole to charcoal canister opening on tank top and make that determination
There are probably other ways of doing this but this is what I would do.

If anyone has alternative ideas please go for it, thanks

GT
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Re: gas tank sending unit from 75 vega

Postby chevyart » Wed Jul 28, 2021 11:54 pm

thanks gt. all good ideas you gave. one thing not mentioned that may be important. shouldnt the float be clocked so it swings side to side and not front to back. front to back may be bad because of gas sloshing on hard takeoffs . side to side float movement would seem to be way for float to still work even in hard takeoffs. when Zeke found these sending units he showed how he had to cut 2 little notches on top of tank at opening to locate the 2 new tabs on the new units disc which i suspect was to clock the float from side to side. WHAT SAY YOU ZEKE.. im going to get the new unit here and start playing around to find the best way to fit it in the tank. Still cant figure out how this long 9 1/4 inch unit fitted in my 5 1/4 high tang. anyone got an idea how that happened(im sure it was factory setup) thanks Art
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Re: gas tank sending unit from 75 vega

Postby gt350fme » Thu Jul 29, 2021 2:09 am

Yes side to side as would be stock clock, as for the additional length this unit FG05G as I can surmise came from a 1980s gm truck not Vega unobtanium.
GT
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Re: gas tank sending unit from 75 vega

Postby chevyart » Thu Jul 29, 2021 8:54 am

thanks again gt. one more question. if i gut unit at green line and reattach it one of the ways you mentioned, it will be at a strigh line pointing at an angle upward, which will also bring the float higher. will i have to bend the tubing back downward to maintain the approximate angle that the unit was originally on? hope i said that right. thank you Art
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Re: gas tank sending unit from 75 vega

Postby gt350fme » Thu Jul 29, 2021 1:23 pm

You may need to bend the float arm or the fuel pipe so that the float arm rests in its bottom home stop for the empty setting, and again needs to home in at the top stop also without hitting top or bottom of tank.
What is the overall throw of your float? You have roughly 5 inches of space, if float throw also 5 inches wouldn’t that be lucky but it’s likely something else.
So the unit is roughly 9 inches and you need only 5 inches , shortening by 4 inches overall will get you real close, then bend float arm if need be for final adjustment, not touching top or bottom tank but yet homing in on the float stops.

I like this unit as a replacement, it has extra fuel lines ports if needed for fuel injection return line etc.
1964 Chevy panel K30
1973 GT Vega Hatchback
1977 Chevy K20
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Re: gas tank sending unit from 75 vega

Postby chevyart » Thu Jul 29, 2021 6:07 pm

thanks 350 GT. fellow that did a nice job(on our site)(named Phil) like you suggested with the brass couplers goes by the name 73 silver GT. he did alot of work to get it right with his sender. i was thinking of cutting off above and below the green line and put a splint into the upper and lower portions of remaining tube and then pinning each side so splint dont come out. my good buddy is a machinist so if i need an exact size splint he can make it and pin it for me.. still totally confused how my long stock sender fitted in the5 1/4 inch deep tank. anyone care to explain that one. thanks again Art in NY
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Re: gas tank sending unit from 75 vega

Postby 73SILVERGT » Mon Aug 02, 2021 6:19 am

I used the Spectre unit # FG05G and cut 2 splices as mentioned above. After these pics below were taken, the fittings were soldered to ensure no air leaks. My car has not been driven yet, but it is running and the pick up seems to work well. My car is a '73 GT with the stock tank.

Image
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Re: gas tank sending unit from 75 vega

Postby zeke » Thu Aug 05, 2021 12:41 pm

Nice work 73silvergt

Doesn't matter which direction the float points. Tank was notched to orient the fuel lines towards the front.
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Re: gas tank sending unit from 75 vega

Postby chevyart » Thu Aug 05, 2021 5:01 pm

thanks zeke. i did not know that info. i just had it in my mind that the float should move side to side instead of front to back. gueaa i was worried about float moving front to back and going erratic on hard takeoffs or hard braking. Art
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Re: gas tank sending unit from 75 vega

Postby Monza Harry » Fri Aug 06, 2021 8:46 pm

Art, during a wheels up (hard) launch you should be watching the sky not that D#$^ed gauge LOL!!! Harry
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Re: gas tank sending unit from 75 vega

Postby chevyart » Sat Aug 07, 2021 6:10 pm

harry my nova has a fuel cell and my wheels(thank god) only come off the ground about 6 inchec.. worst part of the ride is coming through around 8,000 rpms. sender is in vega and i thought the sender would have to er clocked side to side. front to back i would think it would give an erratic movement of float on startups and slowdowns. guess that isnt so(or is it?) thanks for the reply. Art in NY.
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