Rat Bastid
Dunamis Metron
Anyone using a return style fuel system with an OE tank? I’m looking for ideas that are safe and clean.
Fuel tank vent
- Thread starter Rat Bastid
- Start date
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67Dart273
Well-Known Member
We need to start with "what is the year make and model."
Why?
Because up into 69, ALL A bodies had a simple vent to the atmosphere in the filler tube
In 70--71 ish SOME cars had CA mandated evap emission controls and 71-is--72 and later Federally. Additionally, THAT SYSTEM (the evap control system) CHANGED some almost every year to 76.
The first couple years had a big can in the trunk, the vapor separator. There were tubes/ hoses coming into the trunk from the tank, and ONE vent line going clear up into the engine bay. THAT IS your vent AND MUST be open or else other provisions
So if you have a "non evap" car, you have an open tank vent, and can create a return line to the tank
If you have an evap controlled car, either add a second return line, and keep the evap vent line clear for a vent, or else create the 69/ earlier style vent --which is documented in service manuals.
You can download many service manuals........free........from MyMopar
Early style evap system with separate vapor separator. LATER THIS WAS incorporated right into the tank---with only the one 1/2 line going to front for the evap plus the feed line of course
This is the "69 and earlier" atmospheric vent, and any of the overlap years of about 70-71 without evap
Why?
Because up into 69, ALL A bodies had a simple vent to the atmosphere in the filler tube
In 70--71 ish SOME cars had CA mandated evap emission controls and 71-is--72 and later Federally. Additionally, THAT SYSTEM (the evap control system) CHANGED some almost every year to 76.
The first couple years had a big can in the trunk, the vapor separator. There were tubes/ hoses coming into the trunk from the tank, and ONE vent line going clear up into the engine bay. THAT IS your vent AND MUST be open or else other provisions
So if you have a "non evap" car, you have an open tank vent, and can create a return line to the tank
If you have an evap controlled car, either add a second return line, and keep the evap vent line clear for a vent, or else create the 69/ earlier style vent --which is documented in service manuals.
You can download many service manuals........free........from MyMopar
Early style evap system with separate vapor separator. LATER THIS WAS incorporated right into the tank---with only the one 1/2 line going to front for the evap plus the feed line of course
This is the "69 and earlier" atmospheric vent, and any of the overlap years of about 70-71 without evap
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Ironracer
Gearhead
I made one for my 74 Duster, as I did 3/8" line, and a 3/8 sending unit. The unit has a return. Drill a few holes, in the right places, cut a few threads, get a brass nipple,...There's some posts in here that cover it
I plan on using the fuel filter from around an 84 D150 on Vixen. it has the 1/4" orificed return nipple originally designed as a vapor return. I'm just going to use it for a solid fuel return.
67Dart273
Well-Known Member
There are two or three Wix filters (others make them) with built in orifices. One number is 5/16, the other is 3/8 and yet at least one other that is a 90* design
33041:
Wix Filters 33041 WIX Filters Fuel Filters | Summit Racing
I believe 33040 is 5/16, 33041 is 3/8, and 33054 is the 90 design
I'm sticking with a mechanical pump. A full size 1/4" return would make pressure drop off to the carburetor too much. I plan to stay mild to moderate slant 6, so I'm good. Otherwise, I'd run a return regulator with a hot electric pump. I thought about, but that's not the direction I want to go.
I have several of the 5/16 wix numbers. That's what I plan to run.
67Dart273
Well-Known Member
Well the filter 1/4" return has an orifice so return line size does not matter. They are designed just for that, and were used on Jeeps, etc (carbureted)
Yeah, I think it's like .060-.080 or some such. Stock filter for the 80s Dodge trucks.
Ironracer
Gearhead
Are those the filters w/ the return? I thought about em, but when I swapped the tank and hard line, the factory vent was not getting replaced. It was fried, and it seemed less expensive to do it the early 70s way
33054 is the number for the 84 D150.
Ironracer
Gearhead
Wow, so you would run an electric pump, and regulator, on the return?
No. Were I to run an unrestricted return I would go electric pump and regulator. I'm running a filter with a restricted return, because I'm sticking with a mechanical pump. I didn't mean to sidetrack the OP's thread. My bad. Carry on.
Rat Bastid
Dunamis Metron
73 Duster is the car. It’s going to have a number 10 fuel and return line. So I need a vent capable of that much return fuel at low engine speeds/pump demand. I’m trying to find a way to keep the vent from letting dirt into the tank and to make it safe if the car gets into a crash situation. If it was a fuel cell it would be much easier.
Rat Bastid
Dunamis Metron
Thats not a side track. Some very good information getting out there and that’s what matters most.
67Dart273
Well-Known Member
LOL well that puts a whole different light................and I likely won't be much help. One big issue with "build your own" is that you can create a siphon situation if you are not careful.
Ok, so that's 5/8" right? What are you fueling? A container ship engine in your Duster?
Ironracer
Gearhead
Yessir, you have to bend in an " air trap" or " vacuum break" for lack of better terms
Ironracer
Gearhead
I'm wondering...
Rat Bastid
Dunamis Metron
It’s for a friend and is going to do nitrous with it. Because of that and the pump is pretty big (Mallory 250 gph) I figured just start with a 5/8 line both ways and only do it once. That’s a pretty good sized pump. But he got a smoking deal on it so now he has it.
Rat Bastid
Dunamis Metron
Yeah, I’m trying to avoid that too. And like I said, keep junk and stuff from ending up in the fuel tank. I’m thinking at least a 1/2 vent, maybe just do it in 5/8 if I can find the room and several wraps around something that is 2 inches in diameter. I just need to stop junk from getting in there and I need some sort of check valve in case of a crash. I guess I should dish up an NHRA rule book and see what that says about venting a tank.
TT5.9mag
Two atmospheres are better than one
You can buy -10 90 deg fittings with the rollover valve in em. It’s just a check ball. Drill a hole in the top of the tank, install a bulkhead -10 fitting, then -10 rollover valve, then aluminum hardline in whatever size you want with a loop or two, and straight back down and out the underside of the car.
TT5.9mag
Two atmospheres are better than one
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