has anyone done a s4 efi tank into a first gen?
 

hey guys

looked in the archives but nothing of this nature.
my plan was to go efi on my 81 gsl 12a. to a 6port 13b T

problem im running into is sourcing a gsl-se fuel tank locally for this, however there is a few s4 rx7s in the local auto yard. im willing to do the fab work to make this work. but does anyone have the two tanks in question in a comparson side by side with measurements ?? trying to get an idea of how different in size they are. i do know the filler necks are on opposite ends .

i was thinking of removing the spare tire pan and welding a flat piece there and mod the tank straps.

if anyone has pictures that would be really greatfull. thanks guys.

Anything is possible, but the size and shape of the FC tank is completely different. If you want to make a FB tank work for FI do what I, and a number of other members have done, and cut the slosh baffle and fuel pump mounting ring off of the FC tank and weld those parts into the FB tank. An S4 pump hanger assembly is the correct height and will then bolt right in. I have a pic in my T2 thread, I'll find it and post here in a second.
Edit, here are the two pics that show the mounting ring welded to the top and the slosh baffle inside. I admit the plug welds i did on the slosh baffle aren't the best, but its hard to get the mig gun down in there, they are plenty strong and after i took those shots i sealed them up with por15 gas tank sealer so they stay rust free.
You can also weld the ring for the FC's vapor vent assembly, i took an eaisier approach and just welded a piece of brake line in there. Been running this setup for a couple years and other than having the used pump i initially installed crap out on me its been quiet and trouble free!

https://www.rx7club.com/attachment.p...3&d=1172792567
https://www.rx7club.com/attachment.p...4&d=1172792567

that looks promissing. i have a gas mig at work that i know can work ok but will need to clean the welds afterwards. where did you purchase that Por 15 sealer?

You're simply not going to get a better answer than what 82transam posted. That's the best way to go.

The other option you have is to setup a surge tank, (sometimes called a swirl pot?). Then you can leave the stock gas tank alone.

www.synlubes.com has all the por15 products, I also get them at my local auto parts store although they are a but more expensive.... You can just use a wirewheel on a dremel to clean off the welds, but if you are using a gas shielded mig you won't have much to clean up in the first place.

I've modded a couple tanks like posted above. It works quite well. One tank I did went in Dan S Young's 400+ hp widebody. It was set up for dual internal pumps. Fwiw, the FC sump cup holds 4-5 times the volume of the SE cup.

To put an FC tank in an FB is way too much work. The spare tire well would need to be removed and the fill neck is on the passenger side of the body. If you need a tank modded, PM me.

I think Sam (dj55b) is running a similar setup as mine but he changed the fittings on the pump hanger to AN style fittings didn't he?
Renns also did a similar setup and did a nice writeup as well, his was on a SA tank though so it did require modding the hanger (shortening it)

I did Sam's tank too and he spent a small fortune on AN fittings. Never could see spending that kind of money when stock parts work just as well.

Yeah I agree. I just ran new 5/16" aluminum hard lines and got some FI rated rubber hose at the auto parts store and called it a day.

Just to put it up there ... gasket from mazda for those tanks are no longer available. Truthfully the better option would be grabbing the top of a tank of chevy or ford part. Very easy to get and work with, especially something off a corvette or the likes.

Making gaskets isn't hard and something any gearhead should be able to do. Cork gaskets are trickier but one can manage with patience, a sharp xacto knife and scissors.

Gaskets that handle raw fuel ? Personally things like that id rather just buy.

sorry for bumping a dead thread. But I wanted to ask a question: I have a few spare 79-80 gas tanks in storage. The tank in my 81 GS has alot of rust in the inner wall. Can I get a SA tank to work on a FB? My storage shed is a few miles away from my house so I can't compare them. Any one done this before? Or better yet have side by side pics of the FB/SA tanks? Thanks

An SA gas tank should not fit an FB.
The SA has a full size spare, and the FB has a thin one.

Actually, it might fit (like crap), but the FB one cannot fit in the SA.

Thanks for the reply DF. I want to use a S1 tank in a S2. I can't find a S2 tank to save my life. :(

The shape of the tank is similar enough(around the spare tire well etc) that you could probably fit it if you made shorter straps (since the SA tank is shorter) If its your only option you could make it work, but it would probably be easier to sell your SA tanks and use the money to buy a good FB one, just my opinion though :)

You can swap the tanks if you want to swap the spare tire wells too. Take the tank down to a radiator shop and see if they will boil it out and reseal it. The reseal will even seal tiny pinholes that light shows through.

yep, SA tanks fit fine on the FB. Look at grannies website and they did it to fit the huge muffler they got on their mule car. I am actually going with an external fuel pump which requires a bit of work to make happen but I am seriously referencing this page for the good info available (ie pics)

^ Is the external actually much work>? I bolted a Holly Blue and regulator back into the stock position in about an hour (including the time it took me to stop bleeding from gashing my hand pretty good). Why would an external EFI pump be any different unless it's a really big one? I gotta do this soon too, so I was wondering which way to go with it. (in-tank vs. external)

yeah it is freaking huge. i got the a1000 i was told it would require some work

I have taken a 2nd gen fuel pump from a '88 n/a car, and modified the sender tubing on the 12a 1st gen fuel tank and connected a perferated sheet metal wrap around the fuel pump mounted to the bottom of the fuel sender, and now I use a fuel regulator to regulate it to 7psi, but have the option to run as high as EFI fuel pressure :) Probably be easier to take a 84 or 85 13b fuel tank and its external fuel pump, and plumb larger lines to the engine though..

wait the 85 came with an external? hmmm return line?

All FB's came with an external Fuel tank.

Here's some old pics of my A1000 external fuel pump.

I ran -10AN to the rails, and -8AN Returns, I welded on the fittings to the stock GSL-SE pickup and return tubes.

I used the stock Clamps bolts, Some AN clamps, and a few zip ties to hold it all in place.

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