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fuel tank to floorpan clearance?

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Old Sep 25, 2009 | 05:49 PM
  #1  
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fuel tank to floorpan clearance?

anyone have an accurate measurement?
i want to modify my sending unit to take a 90deg bulkhead fitting to properly supply my fuel pump.
i was going to cut a hole in the hatch, but i dont want to hack up the car if i dont have room.
ive found several threads and a few pics, but clearance looks blind by the pic.
http://www.jegs.com/images/photos/30...361-983310.jpg
going to use that fitting, then make a flare on a piece of tubing and run it to the bottom of the tank where the pump used to be for a pickup.
any help is appreciated.
maybe a member has already done this.
thanks.
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Old Sep 25, 2009 | 06:29 PM
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Re: fuel tank to floorpan clearance?

i think stephen posted a pic a while back, you have something like 3/4 to and inch from the floor to the tank. I dont think a 10an 90 will fit, but maybe you could fad up a recessed spot in the sending unit to make some room? I assume you will have to modify the stock setup anyway.
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Old Sep 25, 2009 | 07:17 PM
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Re: fuel tank to floorpan clearance?

was going to grind off all the stock lines and englarge the holes.
if that doesnt work i can drill a new hole.
will need to get a -10 for a pickup, -8 for return, and another -10 for a vent.
ive talked to one guy that says i can feed from the stock lines no problem for my hp, but everyone else in the world says i need a -10 or dont bother.
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Old Sep 25, 2009 | 07:58 PM
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Re: fuel tank to floorpan clearance?

If your worried about it you could space the tank out with some rubber grommets or maybe rubber hose.

That way you could use the stock straps but just not tighten the nuts down all the way.
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Old Sep 25, 2009 | 08:56 PM
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Re: fuel tank to floorpan clearance?

Originally Posted by Arizona IROC
If your worried about it you could space the tank out with some rubber grommets or maybe rubber hose.

That way you could use the stock straps but just not tighten the nuts down all the way.
that may be an option!
you have given me an idea.
if there is a 1/4 inch of room there now, then my idea is useless.
but, if there is 3/4 or so there, and thats not quite enough, ill just loosen the gas tank straps until i can put a piece of metal back flush with the hatch floor.
still would like to get an idea of how much clearance is there before i go dipping into something i cant fix.
thanks for you post.
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Old Sep 25, 2009 | 09:59 PM
  #6  
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Re: fuel tank to floorpan clearance?

how much hp are you running. I thought -10 was huge for a supply. i thought that -6 was could feed up to a 450hp motor and -8 was like 650 or so.

I might be wrong but iirc -10 is huge.
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Old Sep 25, 2009 | 11:12 PM
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From: p'cola FL
Car: 88 iroc-z/28
Engine: 408 lsx
Transmission: 5800 stall
Axle/Gears: 4.71
Re: fuel tank to floorpan clearance?

Originally Posted by 89_ho_rs
how much hp are you running. I thought -10 was huge for a supply. i thought that -6 was could feed up to a 450hp motor and -8 was like 650 or so.

I might be wrong but iirc -10 is huge.
640-650 crank hp.
i have spoke with my carb guy, aeromotive, magnafuel, and also glens performance on a variety of pumps from a big race piece to a walbro340. all of them recommend that it needs a -10 supply for my application.
-10 is huge, BTW.
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Old Sep 26, 2009 | 07:07 PM
  #8  
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Re: fuel tank to floorpan clearance?

hell im only running a little over 500 fwhp and i have a 10an feed and a 8an return line. I just figured go big now so i dont have to re-plumb it all again in a year when i change my mind with the car and swap in a bigger motor. Its the 3rd complete fuel system ive had in a year, so i didnt want to mess with it anymore. So im good up to 1500 N/A horse
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Old Sep 26, 2009 | 09:04 PM
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Re: fuel tank to floorpan clearance?

For that big its time to sump the pan

AN10 is 5/8" ID
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Old Sep 26, 2009 | 09:18 PM
  #10  
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Re: fuel tank to floorpan clearance?

Originally Posted by //<86TA>\\
i think stephen posted a pic a while back, you have something like 3/4 to and inch from the floor to the tank. I dont think a 10an 90 will fit, but maybe you could fad up a recessed spot in the sending unit to make some room? I assume you will have to modify the stock setup anyway.
And here it is again.....
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Old Sep 27, 2009 | 08:48 AM
  #11  
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From: p'cola FL
Car: 88 iroc-z/28
Engine: 408 lsx
Transmission: 5800 stall
Axle/Gears: 4.71
Re: fuel tank to floorpan clearance?

Originally Posted by //<86TA>\\
hell im only running a little over 500 fwhp and i have a 10an feed and a 8an return line. I just figured go big now so i dont have to re-plumb it all again in a year when i change my mind with the car and swap in a bigger motor. Its the 3rd complete fuel system ive had in a year, so i didnt want to mess with it anymore. So im good up to 1500 N/A horse
did you mod the stock tank?
pics?
thanks!
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Old Sep 27, 2009 | 08:48 AM
  #12  
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Axle/Gears: 4.71
Re: fuel tank to floorpan clearance?

Originally Posted by Stephen
And here it is again.....
thank you for the pic, thats almost accurate.
looks like 15/16" of an inch, but its hard to tell.
concur?
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Old Sep 27, 2009 | 09:12 AM
  #13  
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Re: fuel tank to floorpan clearance?

Keep in mind the floor has ridges and the tank isnt flat

Also think about the plate you're putting over it all. It will sit ontop of the floor so your new max height is to the top of the old floor or roughly 1"
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Old Sep 27, 2009 | 09:54 AM
  #14  
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Re: fuel tank to floorpan clearance?

not trying to thread jack or anything.

but what are they ratings of the different - fittings?

also to hook up a -10 fitting to the stock tank i have to assume that you would not even use the stock sending unit. or do you have to completely remove it and basically remove all of the piping the add new piping into the tank also.


this thread has me thinking.
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Old Sep 27, 2009 | 11:52 AM
  #15  
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Axle/Gears: Moser full floater m9, 3:70 trutrac
Re: fuel tank to floorpan clearance?

Originally Posted by stage20
did you mod the stock tank?
pics?
thanks!
no, improtant side note i forgot to mention, its a Nasty Performance fabricated aluminum sumped tank, 1/2" npt outlets.
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Old Sep 27, 2009 | 02:12 PM
  #16  
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Axle/Gears: moser 9" 4.11
Re: fuel tank to floorpan clearance?

I'm running -10 but with a sump. -10 is the minimum that magnafuel calls for with my pro star 500 pump, they actually state a -12 would be better if I needed that much fuel volume. Sure is nice to never see a pressure drop at the hit off the line anymore. I would imagine you could skip the sump and just drill a hole in the bottom like is used for 4th gen tanks but you will have to race with 1/3 tank or slightly more all the time. They just use a typical fuel cell bulkhead fitting in their plastic tanks. I wouldn't run the 3/8" line unless I had a high pressure pump to keep up with, if you're running a carb pressure pump then your advice is sadly mistaken.
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Old Sep 28, 2009 | 08:16 PM
  #17  
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Re: fuel tank to floorpan clearance?

Originally Posted by //<86TA>\\
no, improtant side note i forgot to mention, its a Nasty Performance fabricated aluminum sumped tank, 1/2" npt outlets.
wish i had the room for one, (and the money).
if i did a sump, id have to redo my exhaust setup.
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Old Sep 28, 2009 | 08:18 PM
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From: p'cola FL
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Transmission: 5800 stall
Axle/Gears: 4.71
Re: fuel tank to floorpan clearance?

Originally Posted by 89_ho_rs
not trying to thread jack or anything.

but what are they ratings of the different - fittings?

also to hook up a -10 fitting to the stock tank i have to assume that you would not even use the stock sending unit. or do you have to completely remove it and basically remove all of the piping the add new piping into the tank also.


this thread has me thinking.
could cut the stock lines, redrill, or drill a new hole and make my own feed line.
still need the fuel level to function, so im going to have to work around that as well.
my buddy chris got back with me and said he did the same thing to his 02ss(plastic tank) and a -10 bulkhead fit.
looks like the route i might take.
going to wait till the last Q/S race of the year. prolly turn into a november or december project depending on the weather.
it only gets cold here for a week or two. i might just keep driving it and not worry about going faster... right now. hahaha.
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Old Sep 30, 2009 | 06:04 AM
  #19  
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Re: fuel tank to floorpan clearance?

I'm not trying to hijack, but are we all agreeing that there is about 7/8" of clearance? The only reason I ask is because I am thinking about routing my return line up there.
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Old Sep 30, 2009 | 08:32 AM
  #20  
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Re: fuel tank to floorpan clearance?

Originally Posted by jg04222
I'm not trying to hijack, but are we all agreeing that there is about 7/8" of clearance? The only reason I ask is because I am thinking about routing my return line up there.
You act like everybody is arguing about it, despite with the PICTURE already posted above....
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Old Sep 30, 2009 | 01:02 PM
  #21  
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Re: fuel tank to floorpan clearance?

I never said anyone was arguing about it, I was just trying to get an answer to the question, since stage 20 asked the same question in an above post, and no one answered him. In fact, his opening post asks for an accurate measurement, which is what I too was trying to get.

As for the picture being posted, they often help but are sometimes deceiving...stage 20 read it as 15/16", i read it as 7/8". I was just trying to get a clear, and as was asked of before, accurate measurement. Some of us want accuracy, others can live with just ballparking it and say "Oh, it's around an inch or so". I appreciate the picture you posted, but I was just trying to get an accurate measurement, just like the o.p.
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Old Sep 30, 2009 | 01:11 PM
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Re: fuel tank to floorpan clearance?

Well, the pic is at an angle (can't get a 100% direct side-on shot) but if 1/16" inch concerns anyone for clearance (in the planning stages) for something like THIS?

Last edited by Stephen; Sep 30, 2009 at 02:01 PM.
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Old Sep 30, 2009 | 04:07 PM
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Re: fuel tank to floorpan clearance?

Originally Posted by jg04222
I never said anyone was arguing about it, I was just trying to get an answer to the question, since stage 20 asked the same question in an above post, and no one answered him. In fact, his opening post asks for an accurate measurement, which is what I too was trying to get.

As for the picture being posted, they often help but are sometimes deceiving...stage 20 read it as 15/16", i read it as 7/8". I was just trying to get a clear, and as was asked of before, accurate measurement. Some of us want accuracy, others can live with just ballparking it and say "Oh, it's around an inch or so". I appreciate the picture you posted, but I was just trying to get an accurate measurement, just like the o.p.
if a 1/16 of an inch will make or break you, scrap the idea
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Old Feb 23, 2010 | 10:22 PM
  #24  
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Re: fuel tank to floorpan clearance?

Has anyone done this, fit a return or vent fitting at the top of the tank?
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Old Feb 24, 2010 | 06:48 PM
  #25  
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From: p'cola FL
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Re: fuel tank to floorpan clearance?

Originally Posted by bart91406
Has anyone done this, fit a return or vent fitting at the top of the tank?
i still dont know if its possible, but i am going to try it here in the next couple of weeks.
got a sumped tank, and im going to plumb a larger return and vent. try anyway....
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