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EFI Swap: fuel tank


74Adam

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I searched the archives, but didn't find exactly what I needed. I was talking to Jerry at All Z-East in Ft. Worth about putting FI in my early model 74 the other day. Now, I had always heard that you could use the 74 fuel tank if you put a surge tank somewhere to prevent air from getting into the lines when the fuel level gets low in the tank. Jerry, however, said the problem is that the size of the return line inlet is too small. This is a problem because A. He doesn't have a 75 or 76 fuel tank B. I just got through having my tank boiled out, POR-15 on the outside and new vent hoses installed. Yeah, I should have had more foresight, but here we are. So, what I would like to know is could you have a shop weld in a bigger inlet? I mean if that is the only problem it seems like that would be the best solution. If you guys have any other ideas I am all ears.

thanks,

-Adam

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Since your tank has been boiled out, it would not be hard to add a larger return tube to it. You could take the vent hose , thats right above the fuel inlet/outlet, off and use that as a return if you don't want to do any welding.

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Holy crap, I never would have thought of that. What would you do with the original return inlet then? Just use it as the vent line? Also, is the supply line big enough, or should I still do the surge tank thing? One more question (man, I keep thinking of stuff to ask...lol), do I need to change the fuel lines (supply and return)?

thanks again

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I'm running an efi 327 and added a sump to my stock tank. Go to "www" button below then to page 7, and scroll down.

I would cap off the stock return, you could use Epoxy putty called Sonic-weld, that I bought at NAPA. If you don't want to add a sump, I would use the surge tank. The stock tanks don't have enough baffleing in them.

Are you running a EFI V8 or L6? If it's a stock EFI V8, or L6 the supply/return might be enough. On my engine I'm using 3/8 supply/return.

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I have a stroker L28. It is 3.0 liters (didn't want to take the cylinders out to 83mm), very mild crane cam, 9.7:1 CR. Not a monster by any means.

So, a surge tank is used more because of the baffling issue than a supply issue? Of course, it would help supply too, giving a "buffer" so to speak.

 

I just got off the phone with Jerry. He is pretty much firm on using the later tank. If I am going to have him do the job, I have to let him do it the way he wants. (maybe he doesn't WANT the job...lol)

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It's definitely a baffling issue which gives you supply, with EFI you need constant fuel pressure, and if you turn a corner with a stock tank the fuel sloshes to one side when the level is low and you lose pressure.

With your strocker, I'm not sure if the stock line will supply it. I would post the question at the L6 board.

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This is what I did for a sump:

 

http://www.sweetspotproductions.com/psanders/images/fuel-sump.pdf

 

I drilled out the old return tube on the tank, and silver soldered in a 3/8" hose barb. I ran new 3/8" lines for send and return, but really all you need to do is run a new return. In fact, you can use the charcoal canister return line (the 5/16" line on the driver's side of the engine compartment). Back at the tank. You will need to run new hose from the old canister return line to the new return barb you just installed. I've never done it, but it seems like it would be possible. It will savev ou from running a new line (which is a pain in the butt). 5/16" line is plenty big enough for your stroker. I know of people getting over 230HP at the wheels wit the stock fuel line.

 

Pete

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Thanks for all your help guys. A guy saw my post on zcar and is going to sell me a 75 tank for 75 bucks. Pretty good deal and I think I'll jump on it. Of course, now I have a nice tank that I had cleaned and painted that I won't have any use for :-(

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Oh, I just thought of something else...lol. I have heard that the 75 intake is desireable because it is the cleanest (no egr for example). Unfortunately it also doesn't have a oxygen sensor, which I want. So, can I use a 75 intake with later electronics or is it best to get EVERYTHING from one donor car?

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I don't like the N42 (non-webbed, non-EGR) manifolds. I had problems with heat soak on my turbo motor. May not be a problem with an NA setup. I've got two of them if you want one. One is already painted, and ported for a 240SX throttle body. I used it one season. This year I'm running a turbo manifold with the EGR and other un-needed ports welded up and smoothed.

 

Yes you can use the N42 manifold (75'-76') with later electronics because the O2 sensor goes into the exhaust manifold, not the intake manifold. You may need to play around with the IAC valve, but should be doable.

 

Pete

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