[LynnB]

It isn't necessary to do an in tank fuel pump. BMW used external pumps for decades on FI cars. For my 83, I use a Walbro pump.
Of course, then you will need to figure out how to plumb a return line. Shouldn't be to difficult. Return line is very low pressure.

 

[GThound]

It is still too hot too touch, but here is the rough casting of the top piece, and I ordered a Walbro pump.

 

[SpringGT]

It is still too hot too touch, but here is the rough casting of the top piece, and I ordered a Walbro pump.
View attachment 444239


View attachment 444232 View attachment 444233 View attachment 444234 View attachment 444236 View attachment 444237

Nice work! Thanks for posting.

 

[GThound]

Here is the casting cleaned up a bit. It is proof that I need quality better casting sand, more patience, better model building skills, better mold packing technique. Or a combination of the above. The sand was too dry and breaking away at the edges, but I decided to pour the metal anyway. It looks like it could have been a steam/ venting issue. The good news it is oversized so Hopefully I can machine down past the imperfections and at the very least see how it drills and taps

 

[LynnB]

Still, hats off to your for your efforts. I have "over engineered" more than one car mod in the last 53 years. If you end up with something you like that turns out to be functional, it is a success; and hugely satisfying.
What we call "trial and error" the big companies call "research and development." The only difference is the budget.

 

[GThound]

After drilling the 8 flange holes, 2 holes for the 1/4 NPT fittings and cleaning up the surface with fly cutter on my mini mill, it looks like this.

 

[GThound]

So next steps on this project…I need to decide / identify / source:

1. Fuel fittings that will thread into the cast aluminum top and Connect to low pressure barb fitting internal and high pressure connection to fuel lines outside. Stainless? I am thinking maybe a street elbow screwed into the top, then, a barbed fitting onto that on the underside of cap to connect to fuel pump outlet
2. Thread sealer: I am thinking permatex 85420
3. How to seal flange bolts. I am thinking a nitrile o-ring on each of the 8 mm stainless socket bolts
4. Nitrile rubber sheet to make the 6” diameter flange gasket
5. 3D print and Cast the refined new bottom ring (Fun Foundry Day)
6. Fuel proof electrical seal. Thinking about terminals that pass through plastic/rubber seal or moisture proof electrical seal, or a grommet and some sort of sealer.
7. Siphon to drain fuel from tank (I am below a 1/4)
8. Fuel tank sealer (I am thinking POR 15). It have never tried such a product
9. Make fuel line material decision and procure new supply line. braided nylon? Aluminum hand form line? Stainless steel fuel line?
10. Fabricate the pump bracket (Fun TIG welding day)
11. Fabricate fuel tray (dub TIG weld day)
12. Assemble the in tank fuel pump module

 

[GThound]

Might abandon this project as some folks have pushed on safety concerns and just cough up the extra money for the Holley Sniper in tank fuel pump. That way I can focus efforts on finishing the SLANT DRAFT manifold project.

 

[DavidF1972]

As far as I know, there is no silicone RTV sealant that is impervious to gasoline.

From the data sheet: "3M(TM) Marine Adhesive/Sealant 5200 is not recommended for use as a teak deck seam sealer. Extended exposure to chemicals (teak cleaners, oxalic acid, gasoline, strong solvents and other harsh chemicals) may cause permanent softening of the sealant."

I've used 3m5200 for over 20 years and have never seen it effected by gasoline. I used it for sealing the crank cases of outboard motors in place of permatex #2.
It might not be "recommened" but it will certainly get the job done.

 

[LynnB]

Your car; your choice David.
I would not use it in direct contact with gasoline; especially in this application. If that seal fails in the GT, it will be putting gas fumes inside the car. Most cars and trucks, the tank is more isolated from the inside of the vehicle.
Besides, the MANUFACTURER advises against use where it will be subject to extended exposure to gasoline, among other things. Better off using something that IS recommended for the application.
Just thought the OP should have all the facts.

 

[DavidF1972]

Your car; your choice David.
I would not use it in direct contact with gasoline; especially in this application. If that seal fails in the GT, it will be putting gas fumes inside the car. Most cars and trucks, the tank is more isolated from the inside of the vehicle.
Besides, the MANUFACTURER advises against use where it will be subject to extended exposure to gasoline, among other things. Better off using something that IS recommended for the application.
Just thought the OP should have all the facts.

Yea ok, why don't you actually try the product before condemning it?? They the MANUFACTURER say they don't recommend it, but they don't say absolutely not!! They say it may soften I'm contact with gasoline, but not that it will. Might loose a bit of durometer, but doubt it would ever loose seal.. think about how much more abuse it takes on an outboard (2stoke) crankcase.
Hell, Ivory soap doesn't say it can plug a hole in a gas tank, but it sure will, for 30 years now...
It all comes down to liability
I would atleast recommend a test....

 

[LynnB]

Someone got up on the wrong side of the bed. No desire to enter into a pi$$ing match. You win if it is that important to you.

 

[DavidF1972]

Someone got up on the wrong side of the bed. No desire to enter into a pi$$ing match. You win if it is that important to you.

Ummm??? Did you not say MANUFACTURER?? Big bold letters???
There's no wrong side of the bed to get up on. As long as you get up

 

[terrylewisac]

Hell, Ivory soap doesn't say it can plug a hole in a gas tank, but it sure will,

That's right, drug smugglers have used that trick for years for leaks in fuel systems in planes