Fuel Tank Flanges

[C9]

Sometimes I can't believe all the pain in the butt problems I've had with the fuel tanks in my 32 roadster.


First time around was the standing on it's edge in-trunk tank from LTL.
Sorta similar to the standing on edge, inside the cab tanks found in 50's and 60's pickups.
It had it's problems and potential problems.
Along with costing $400. plus shipping in 1992.


The saddles that came with it have very sharp edges and it looked like it would wear through the poly tank - or whatever kind of soft waxy plastic it was cast from.
I took that into account and made some soft pads, but not soft that they'd wear through in no time.
The main idea was to get the tank up off the saddles an eighth of an inch or so.


The LTL tank had a couple of 1/4-NPT brass fittings molded in at the bottom corners.
Fairly well done, but if you get a leak you're gonna have 15 gallons or so of gas sloshing around the car floor.


The really bad part about the LTL tank was the filler pipe.
It was nothing more than a short piece of about 2" diameter black plumbing pipe with pipe threads at the bottom and fine threads for the aluminum cap at the top.
LTL's instructions called for wrapping the plumbing pipe with Teflon pipe and screwing it directly into the top left corner of the tank where there was an opening that had threads cast in.


Like you'd think, it didn't work worth a *.
Gas leaked out into the car via the poor thread seal.
Same thing happened again, this time with a few more - within reason - wraps of Teflon tape.


This 2nd time around, a lot of gas leaked out into the car.
A scary deal, but I pushed the car off to the side of the lot, when it quit dripping I moved it again, fired it up, took it home and pulled the LTL tank.
All the while casting many bad words toward the idiots at LTL and vowing nevermore.




So . . . a few days later, I sprung for a JAZ fuel cell.
A much better setup, but it constantly weeped a small amount and the capacitance fuel sender died about the 3rd year out.
No big deal, keep track of the gas stops via the re-settable trip odometer and fuel pressure gauge.
The gas stop deal worked well for a long time then the odometer hung up on the VDO speedo and I ended up "borrowing" the new SW speedo from the 31 . . . which was replaced with another new SW speedo.
I told myself I wouldn't be swapping things back and forth between the 32 and 31 roadsters and so far, that's the only thing I have swapped/borrowed/stole outright.


I did regasket the JAZ fuel cell three times - with new gaskets - and it still weeped.
Potentially dangerous which is kind of funny since it's supposed to be a safety device.


The problem with the JAZ fuel cell is two-fold.
The outer skin of the cell is cast with a pebbled finish and they didn't have the brains to cast a smooth finish in where the gasket would sit.


The other problem is the inside the tank retainer ring.
It's an about 1/8" thick ring with 1/4" bolts or studs welded to it and the poor welds allow fuel to come up the studs - since they're not sealed - and weep out over the filler neck at the flange.


I don't seem to be alone in owning a weepy JAZ fuel cell.
Talking to several drag racers, they've commented, "They all weep a little bit."
A strange sounding comment to me since I believe safety devices should not introduce their own dangers.


So JAZ is pretty much off my shopping list.




Last thing tried was a Summit RCI fuel tank.
They call it a fuel cell in the catalog and online, but it has absolutely none of the attributes of a fuel cell.
Unless you want to count the flange leak.
I say leak, but it was more like a small waterfall.


The Summit tank had no baffles like a fuel tank should have and no foam like a fuel cell should have.


Kinda ticked me off that the Summit tank leaked so bad.
My pal had one of these in his roadster and it worked great and to an extent is what convinced me to give the Summit tank a try.


I did wonder about the brilliance of selecting a 90 ohm fuel sender instead of the more common 233 ohm sender which would've matched my 233 ohm SW gauge already in the car.


I ordered an SW 90 ohm gauge at the speed shop and dinked around for two months before me and the speed shop guy cancelled the order since SW said they only made special runs of the 90 ohm gauge and weren't going to do it for a while.


So I ordered an Autometer 90 ohm gauge from Summit, quick delivery, good service like always and 20 minutes after the UPS truck dropped off the Autometer gauge, the speed shop called and said the SW 90 ohm gauge was in.


Before I get too much further along, let me say that I'm still dealing with Summit, never had a problem with them before.


I decided to fix the fuel flange setup myself and here's how it went . . . pics and all....



This first pic shows the inner retaining ring with bolts - incompletely welded so just like the JAZ cell, fuel poured out from the stud holes on the supplied tank flange that carries the filler tube and aluminum cap.
Interesting part about the tank flange was that it was 5/16" off flat.
It's for sure a 1/8" thick rubber gasket is not gonna seal that much of a non-flatness (to coin a word) as well as seal off the many small holes in the bolt/flange interface where the studs were poorly welded not to mention that several of the studs were leaning.


The ring is cut when installed so it can "roll" into a smaller hole than the rings outer diameter.
There is no gasket of any kind between tank and inner stud ring.
So what we have here is one lonesome gasket trying to seal off two tank/flange interfaces.




These next two pics are just a quick look at machining a 1/4" thick round disc from flat plate.
Use 6061 T6 aluminum for the flange discs.
The big hole saw saves a lot of time boring a large hole.
Plus, you end up with a smaller disc you can save for other projects.
Beats heck out of making a pile of chips that nobody can use.





The pic of the finished flanges shows the home-made gaskets Copper-Coated on.
The gaskets are .030 thick rubber/fiber composition that you can find at CarQuest and NAPA stores.
US made, the stuff is easy to cut and works well.
In fact I made a set of intake gaskets for the 462" Buick in the 32.from the gasket material.
They're still working great.
Way better than the thin sheet metal gaskets supplied by most of the gasket manufacturers.




Shown here are the flanges.
Note that the outer flange carries twelve 1/4" - NC one end, NF the other - studs and is also drilled as well as being countersunk for twelve 1/4-20 stainless FH buttonhead allens in between the studs.
The studs are installed with Permatex . . . #2 I think it is.
Whatever it is, it remains soft.
I would have used a hard cure Permatex gasket shellac, but so far this is working fine.



The inner flange was drilled and tapped to accept the1/4-20 (NC) stainless FH allens.


You'll note that a fairly wide part of the inner ring was cut away.
Reason being, the thicker 1/4" aluminum doesn't flex at all and the wider piece allows for two very narrow slots when assembled so that will help keep the gasoline from getting between the inner ring and underside of tank top.




This pic shows the initial part of the install.
You can see the inner ring 'key' that gets bolted in with one bolt as well as all but one of the FH allens in place.
The wider slot cut in the inner flange is just about the minimum size for rolling the inner flange into the tank hole.





This shows the completed installation.
The tank has a feed line fitting installed, a vent fitting with safety blockoff - for upside down - and a return line fitting that is not in use here.
The large cast JAZ 45 degree filler neck has a 2 ½" diameter tube for the filler tube.
Nice part about the cast aluminum filler neck is that it has a safety block off that shuts off the filler tube if the car gets upside down.
Not shown is the 18 gage sheet aluminum firewall between trunk and cockpit.
Even with that, I still don't care for fuel tanks or cells in the trunk of a car, but I kinda backed myself into a corner with this one when I used the room where a couple of underbody, within the frame tanks would go for the battery and fuel pumps.




I'm pleased to report the fuel flange no longer leaks.


The thinking behind the double flange setup was that three gaskets would be sealing off three flange interface areas as well as isolating the studs from any potential leaks in the studs proper.
The inner ring's gasket goes up against the underside of the tank's top skin.
The outer ring's gasket goes down against the topside of the tank's top skin.
The FH allens clamp the two together.


Since the studs are 15 degrees away from the FH allen bolt tops, the gasket has a fairly wide area to seal any potential leaks from the FH allens, but since we're not dealing with shoddily welded, exposed to gasoline  inner ring studs there's really nothing to leak.


The cast filler - with it's own gasket - draws down on the outer rings 1/4" studs and seals that area.
Again, incoming gasoline can't get to the studs and since they're well sealed even if some gas got over there, they wouldn't leak due to the stud seal at the threads..


Finishing touches were 1/4-28 (NF) nylocks holding the 45 degree cast filler's flange down.


I realize there's five hose clamps holding the rubber hose - genuine gas filler rubber tubing - but eventually there'll be eight.
I like double hose clamps in critical areas and ran out because the original fuel cell installation only had two filler tubes instead of the three shown.



These last two pics, the result of driving home in a thunderstorm in a once clean car.
Never missed a beat even with all the hood louvers.
Forded a pretty deep and wide gutter with the car too.


Heck, I even stayed dry except for one little place where the rain came in the open - like in non-existent - side window.




It's flat amazing how fast running water builds up out here in the dez.
Once the rain has been on for a while, runoff can get pretty deep, but when the cloudburst hits, you really need to think about the route you're taking because the streams, crossings and rivers fill up pretty quick.
We have some well traveled areas that will swallow a car in no time.


I'm pleased at how well the project turned out.


In retrospect, Summit would more than likely have sent me a new tank or given me credit.
They're a good outfit to deal with, but in this case, the Quality Control people were seriously lacking.


They did remember to hang the "Tested for Leaks" tag on the tank though....