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Discussion Starter · #1 ·
Hello all,

I am thinking about modifying the stock fuel tank and fabricating a low rear sump on the bottom of the tank similar to this:

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I have a couple questions about this... Almost all of the tanks both stock and aftermarket cells have sending units, and lines come in from the top. Why are systems set up like this? What are the benefits/drawbacks of having a low rear exit for the fuel vs. sending unit? Which would you consider better for drag racing, and regular street use?

Currently my car is carbureted, but i will be switching it to an efi system at some point in the near future.
 

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Eric, Have you looked into the Tanks Inc tank for the 2nd gens. $210 for a brand new tank EFI ready uses the walbro intank fuel pumps or you can use there pick up and run your mechanical for now. I have the tanks inc set up on my 70 with EFI and love it I ran this set up with a return regulator and my Q-jet for a while and it worked great. THe in tank baffles system stoped my fuel delivery problem under hard acceleration.

I have the low rear sump set up for my 80 TA I am working on now just like the above pic. It has to work better for drag racing. The fuel on the original set up gets forced to the back of the tank and away from the pick up. I am not crazy about the look of it and fuel line routing.
 

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You will still need a baffle even for the weld on. Most just drill a few holes in the tank and use that as a baffle. I designed mine like a drag racing oil pan with baffle n the rear to trap fuel in the sump under hard acceleration.

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'70 Esprit TA clone Pontiac 400
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I'm installing a Holley HydraMat. Don't like the look of the sump in the rear and while the car will still see drag strips it also gets used on road courses. Should help lower track weight because I won't have to carry as much fuel to prevent starvation anymore. As long as any portion of the mat is in contact with fuel it will draw it.

005_zpsu2wxawst.jpg
 

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Discussion Starter · #5 ·
Eric, Have you looked into the Tanks Inc tank for the 2nd gens. $210 for a brand new tank EFI ready uses the walbro intank fuel pumps or you can use there pick up and run your mechanical for now. I have the tanks inc set up on my 70 with EFI and love it I ran this set up with a return regulator and my Q-jet for a while and it worked great. THe in tank baffles system stoped my fuel delivery problem under hard acceleration.

I have the low rear sump set up for my 80 TA I am working on now just like the above pic. It has to work better for drag racing. The fuel on the original set up gets forced to the back of the tank and away from the pick up. I am not crazy about the look of it and fuel line routing.
Dave,

Does this tank actually come with an EFI pump/sender installed all for $240? http://www.tanksinc.com/index.cfm/page/ptype=product/product_id=447/mode=prod/prd447.htm

I'm installing a Holley HydraMat. Don't like the look of the sump in the rear and while the car will still see drag strips it also gets used on road courses. Should help lower track weight because I won't have to carry as much fuel to prevent starvation anymore. As long as any portion of the mat is in contact with fuel it will draw it.

005_zpsu2wxawst.jpg
That Hydro mat looks AMAZING! Perfect to put in the sump area of a tank. It is extremely pricey though. I wonder what its made out of :ermm:
 

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Unicorn fur and assembled by leprechauns :)
 

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Discussion Starter · #7 ·
You will still need a baffle even for the weld on. Most just drill a few holes in the tank and use that as a baffle. I designed mine like a drag racing oil pan with baffle n the rear to trap fuel in the sump under hard acceleration.

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Derrick, what type of metal/thickness do you use for an add-on rear exit sump? Also, do you put a strainer on the inside of the tank, or just a large fitting with a filter on the outside?
 

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']['exXxas']['itan
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Im going with an inline screen filter to pump(-10), and then a fine element filter downstream(-8). I used 18g std cold roll plate to build mine. Got 2 big sheets 3'x5' for 12 bux....Ive used it to build all kinds of stuff already. The welding was the hard part. 18g is a little harder to weld without blowing holes. Also I pressurized my tank to about 20psi, heated the welded edges with a heat gun and then sprayed soapy water and looked for bubbles. Had about 6 leaks. I did learn 1 thing....dont try to weld up the leaks while the tank is pressurized LOL...talk about a hole!

I ordered 1/2NPT nodular iron bungs off of ebay for like $7.00 free shipping. then just welded them on after cutting holes with a uni-bit.

In the top left pic, you can see the divider between the 2 sections(internal). I will return bypass fuel to the small chamber and didnt want fuel from return being sucked back into the feed side.

I have put 3 HDD magnets inside the tank to catch any metal particles.

For what is worth, If I had a cell laying around or could have scored one second hand for cheap, I woulda went with a cell. If your going EFI, then dont bother with rear sump.
 
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We've used the Holly HydraMat in our shop with fuel injected cars but we also located it in a dropped sump in the rear of the tank so the fuel would get forced back upon acceleration. We're also a fan of baffles so when the tank is a bit low and you have to brake hard you don't end up with a no fuel situation when you get back on the gas. The complete tanks from tanks Inc. and others are good options too depending on what you want to spend.
 

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Im glad i found this thread because i have been searching like crazy about sumps and fuel pumps.
Right now i have a mechanical.
My tank is dropped and fuel lines have been taken out to the rubber couplings so i want to just update the fuel system.

I am wanting to go with a Holley Hp150 pump (not that it matters) but i was just about to go order one and i read past something.

These tanks feed or pull from the top. Electric pumps need gravity to then push fuel to the motor. So my big question is this.

Can i put an electric pump on my car with the factory line exit from the top of the tank? Do i 100% need a sump to run electric?

What im worried about here is not having enough fuel get to the pump and then have starvation/pump wear issues.

I was planning to mount my pump level with the bottom of the tank but at this point how is that even helping if the lines come from the top.

Id really appreciate some help on this! Sorry to put it in this thread but id hate to make a whole new one for one question

Sent from my SM-G920P using Tapatalk
 

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I personally would never run a std "pusher" type electric pump fed off of the top tank type line. They take forever to prime and an bleed back will cause you to have a slow start condition.
 

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So i should really have a sump. Well that threw a boulder in the way lol
Im glad i read that now though before buying stuff.

Is there any place that has a sump on a factory tank? I dont really want a cell in the trunk.

Or if not a factory tank is there a cell that can be mounted in the factory tank location?

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Discussion Starter · #14 ·
So i should really have a sump. Well that threw a boulder in the way lol
Im glad i read that now though before buying stuff.

Is there any place that has a sump on a factory tank? I dont really want a cell in the trunk.

Or if not a factory tank is there a cell that can be mounted in the factory tank location?

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Stated in the above post, Tanks Inc make EFI and Carb sumped original reproductions. They are about $210 for the tank only, which is reasonable considering they have a sump installed.

My question is that if i modify the stock tank for a rear exit sump, and mount an external fuel pump, is there going to be a really loud and obnoxious humm? I understand that there will be a little bit of noise with any electric pump, but i just don't want the pump to sound like it's out of place for the car.
 

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I have yet to find an uber quiet pump. Ive heard the edelbrock electric pumps are very quiet but I cannot confirm. I do know you have to isolate the hell out of them with soft rubber mounts...like .500" thick on both sides of the pump bracket. Others have mounted them with springs trying to get them to shut up. My old barry grant pump was pretty loud but it was a 280gph pump...

Realistically, a mechanical pump is best bang for the buck considering the mods you have to do for an electric pump.
 
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