Danno74Z Posted February 26, 2012 Share Posted February 26, 2012 After looking and studying what other Members have done with the FI LS1 tank, I decided to go this route with my build. The one main objective was to hide the tank from view from the rear of the car. I can’t stand seeing a gas tank hanging down below the valance. To me it looks like a Jeep – but that is just me. The other objective was to open up some options for the muffler/s. I plan to run dual exhausts and I need some room for that. With this setup I can definitely run mufflers on either side of car or put one muffler under the tank (with the proper shielding) or run and exhaust system used on a Corvette. But I’m getting ahead of myself with that system as that is really tight. I used a 1987 300ZX fuel tank. I purchased the tank from a wrecking yard and got the tank, straps and fuel filler neck and piping. I removed the existing 260 tank, filler neck and associated hoses. After studying all the possible locations and my goals I needed to raise the tank as far up as possible into the car. This might sound crazy to some but I went for it. I removed the existing spare wheel tub using a spot weld removal tool. Somebody may need a rust free tube and I just did not want to hack/cut it out – again that is me. I then went and cut a piece of 20 gauge sheet metal piece to fill the hole and welded it in. As everybody here has experienced the original Datsun sheet metal is very thin (probably why the cars are so light) and the under coating is a royal pain in the ass. I made the mistake on trying to weld on clean metal (topside) with undercoating still on the underside – CAN’T BE DONE. I blew right through the metal! It almost acted like I did not have shielding gas. To make a long story as short as possible I went to Harbor Freight and got one of those $19.95 multi-tools. I can’t take credit for this idea as I read about it online. This tool work great for bussing off the old hard and soft undercoating. It makes one hell of mess but not many alternatives. After removing as much of the undercoating with the machine I used some acetone with a rag to get the rest and was down to plain clean sheet metal on top and bottom to make nice clean welds. If I were to do this again, I would ditch the idea of filling in the hole left by the removal of the spare wheel well and just go with a clean piece of sheet metal from the left cross member to the right. That whole area back there (on the 260Z) is boxed in and would be much easier to deal with using clean and smooth new metal. The existing metal has many undulations stamped into it and it is difficult work with and is thin. After I installed the tank and raised it as far as I could inside the car I did some experiments to make sure I could still get a full load of gas inside the tank. Trying to remember my HS physics (2 years after we landed on the moon) and fluid levels I got a coffee can made a little fuel tank and used water not gasoline. The tank opening is in the middle of the tank not at the top like most tanks. But my little experiment worked and I’m satisfied that I will get a full load of gas in the tank when I it fill up. The tank is enclosed within a steel cage firewall for safety. The cage is removable from inside the car as a unit or if I need to access just the sender or pump I have access panels for that. The cage was a ton of work!! Not have sheet metal tools I fabricated the whole thing by hand. If I were to do this again I might get a quote from a fab shop that has benders and brakes and could whip up a cover. It would also be lighter. But I like doing this stuff and I really improved my welding skills The filler tube was a real challenge and I used a combination of 1-1/2†exhaust tubing and the 300ZX filler neck. I even used a little bit of the 260Z stuff. I have to modify the plastic panel just a little that covers the rear tail lights. No surprise there! Changing burned out bulbs will be more difficult but really how often does that need to be done? I will put all new bulbs in and be done. I also made the straps you see on top of the tank. Do I need them probably not but I’m a bit paranoid with gasoline and I don’t want that tank to move if I’m in an accident or God forbid a roll over. I can’t think of anything else and the pictures should fill in the blanks. If you have any questions fire (ask) away. Materials and parts used: Gas tanks support using 1â€x1†thick wall tubing Tank firewall cage material ½†x ½†steel tubing 1-1/2†aircraft exhaust tubing The tank is from a 1987 300ZX and has outside dimensions of 30†long, 21†width and 12†depth Autometer 5417 (to match other gauges) 240Ohms Empty, 33Ohms Full Sender is a Moeller Marine 35762-10†reed type that matches the Ohms of the 5417. This sender does not use a float arm (see pictures) Sheet of 20 gauge sheet metal Quote Link to comment Share on other sites More sharing options...
soga280z Posted February 26, 2012 Share Posted February 26, 2012 Very nice work! Looks great. Quote Link to comment Share on other sites More sharing options...
JustAFantaZ Posted February 26, 2012 Share Posted February 26, 2012 Will the stock fuel gauge work with a tank conversion? Quote Link to comment Share on other sites More sharing options...
rags Posted February 26, 2012 Share Posted February 26, 2012 Wow, that looks great! One question, how far above the floor is the top of the tank? Do you think the standoffs and dummy floor for the late 280z would be high enough to clear the tank? Also, the fuel level sender you chose doesn't have an ohm range anywhere near the stock S30 range. Would you happen to know the range of the 300ZX unit? Your design seems to leave a lot of room for a center exit exhaust which I am trying to do. Looks like I'm gonna start searching for a 300ZX tank and filler Joe Quote Link to comment Share on other sites More sharing options...
Danno74Z Posted February 26, 2012 Author Share Posted February 26, 2012 (edited) Thank you for all the nice compliments! JustAFantaZ No the stock gauge will not work with the sender I'm using. I have and will use Autometer 5417 (to match my other gauges) 240Ohms Empty, 33Ohms Full. I suspect you can get a sender that is close to what is needed for the stock gauge and use the proper resistor as others have done. rags The top of the tank is 5" above the existing floor but more importantly below the filler. Before I welded up the neck, I took whole setup to a gas station to see how far down the pump feed would go and I am above the top of the tank. I will get a full load of gas but after the tank becomes 3/4 full I suspect I will have to put the gas feed on the first click of the handle because of surge. I can live with that The new tank capacity is 19 gallons I tried to figure the 300ZX ohm range and I got some VERY strange readings so no I don't know. I will try again for you. That is exactly what I'm trying to do - Center Exhaust. Over the next few weeks I will mock up an exhaust system to see if there is enough room back there to mimic the corvette system. I made this to start that process. The dimensions are exactly the same as the real muffler but cost me $7 in parts and some time. I have two built and will use 2" PVC pipe (which is close to 2.5" exhaust) to route the center exhaust. I'm nowhere near putting a rear exhaust system in but I'm very curious now that the real tank is in place to mock up the exhaust. I won't cut the rear valance just yet! I know the 280Z's have a raised floor in the hatch area but I have never seen one. My car is an early 260Z which does not have that raised panel. I can't help you there. This is a fake mufffler Edited February 26, 2012 by Danno74Z Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.