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Converting to MSD atomic EFI

Honestly I don't think it would be worth it. Even under normal conditions the baffle fairly consistently seems broken, and I'd expect they would potentially fail pretty quickly under fairly hard wheeling conditions.

All the ones I've seen that have failed seem to have broken by fuel sloshing...the clips holding the baffle to the bottom of the tank pull through the seemingly brittle plastic.
 
I have the Spectra version. As I recall it came unpainted. No issues with it other than my dislike of the baffles. I think that's going to be across the board though, I've yet to see one that impresses me compared to the GM design.

I can't vouch for any of the other brands out there, it seems there is a fair variety now. When I got this one I believe Spectra was one of very few companies making them so it's not like I had much choice.
 
Agreed. Lots of us are running the Spectra tank with EFI conversions and the only issues happen when you're in that last couple of gallons of gas. To do better takes quite a bit more thought, money or maintenance (i.e. fuel cell in the interior, custom in-tank sump or dissolving hydra-mat).
 
Blue85 said:
Agreed. Lots of us are running the Spectra tank with EFI conversions and the only issues happen when you're in that last couple of gallons of gas. To do better takes quite a bit more thought, money or maintenance (i.e. fuel cell in the interior, custom in-tank sump or dissolving hydra-mat).
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When I was still doing a lot of wheeling, I was thinking about putting some kind of accumulator in between the engine and the tank.
I noticed on my diesel with the big fuel filter, I never had a problem because by the time I was going to finish the fuel in the filter I was back to level and the fuel was restored.
I am just trying to figure out something a little bigger like 1 gallon.
 
There are a couple of EFI suppliers offering under-hood surge tanks. In general, I think the idea is draw from a carb fuel tank and boost to EFI pressure under-hood. One of them is Edelbrock. IIRC, experiences have not been great and a lot of users ended up converting to in-tank pumps (avoiding that is presumably the appeal of these setups).

For an accumulator, as the tank pickup is uncovered, it will start to send air. How does that air get out of the accumulator? By gravity it feeds through the return line back to the tank?
 
Blue85 said:
There are a couple of EFI suppliers offering under-hood surge tanks. In general, I think the idea is draw from a carb fuel tank and boost to EFI pressure under-hood. One of them is Edelbrock. IIRC, experiences have not been great and a lot of users ended up converting to in-tank pumps (avoiding that is presumably the appeal of these setups).

For an accumulator, as the tank pickup is uncovered, it will start to send air. How does that air get out of the accumulator? By gravity it feeds through the return line back to the tank?
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The way I was imagining it is to have the inlet on top, outlet on the bottom so air doesn't create a problem.
 
I agree, I am not a fan of the dual fuel system setups that use another pump and a float, etc. It just makes the system more complicated than it needs to be, for what, so you don't have to drop the tank and do it right? Doesn't really save much money and doubles the parts to go bad.
 
folkenheath said:
I agree, I am not a fan of the dual fuel system setups that use another pump and a float, etc. It just makes the system more complicated than it needs to be, for what, so you don't have to drop the tank and do it right? Doesn't really save much money and doubles the parts to go bad.
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I wouldn't be doing it for that but to give my engine a few minutes of fuel while in off camber situations.
 
imiceman44 said:
I wouldn't be doing it for that but to give my engine a few minutes of fuel while in off camber situations.
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Yeah I was talking about the under hood high pressure conversion setups. Yours is different, though I have never had that problem thus far so it isn't really necessary for most people. Reminds me of the accumulators for engine oil Moroso sells.

Though I think it would be harder to seperate the air because if you are in a situation where you lost the fuel at the sump, that means gravity isn't going to bleed air correctly at your bleed hole either. If you really want to get into that, look into the designs they use in airplanes that can fly upside down or sideways without losing fuel supply.
 
folkenheath said:
Yeah I was talking about the under hood high pressure conversion setups. Yours is different, though I have never had that problem thus far so it isn't really necessary for most people. Reminds me of the accumulators for engine oil Moroso sells.

Though I think it would be harder to seperate the air because if you are in a situation where you lost the fuel at the sump, that means gravity isn't going to bleed air correctly at your bleed hole either. If you really want to get into that, look into the designs they use in airplanes that can fly upside down or sideways without losing fuel supply.
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Oh that is exactly what I'm trying to do.
I hade a rc airplane and I saw how it was setup
 
Hey guys,
So I acquired an out of tank efi fuel pump from a member here, I still want to run a return line, so I’m wondering if I can use my current gas tank, and just swap to a sending unit with 4 “holes”. That would allow a filler vent, tank vent, return, and outlet, thinking I’d run soft hose to the pump, then use the hard line as the supply and run efi soft hose for the return, or vice versa use soft hose as supply and hard line for return.. either way.. here is a link to a sending unit
that fits 78-86 tank with 4 holes.. am I missing anything?
 
This thread discusses the in tank baffle you would be missing if you did that. It is better if you get the EFI tank from an 87 model along with the sending unit.
 
Oh I didn’t realize the the carburetor tanks had no baffles at all
 
From what I’m reading the filler necks on the TBI tanks are 1 3/4” and the carb tanks are 1 3/8”, I assume this means the outlet of the filler assembly where you put the nozzle in is also 1 3/8”. What’s the best way to adapt this? I imagine it would be hard to find a hose that changes size from end to the other, could I cut a small portion of the 1 3/8” hose and leave it on the filler outlet then slide the 1 3/4” over that?
 
I slipped the smaller hose on first, then clamped the bigger hose over it. Actually forgot I had done that. Been that way 8 years now, must be ok
 
HawK5 said:
From what I’m reading the filler necks on the TBI tanks are 1 3/4” and the carb tanks are 1 3/8”, I assume this means the outlet of the filler assembly where you put the nozzle in is also 1 3/8”. What’s the best way to adapt this? I imagine it would be hard to find a hose that changes size from end to the other, could I cut a small portion of the 1 3/8” hose and leave it on the filler outlet then slide the 1 3/4” over that?
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Pretty much
 
Well I’ve been collecting parts and have come up with a few questions, got the tank and sending unit, still need to get the oxygen sensor.
1. I believe the fuel pump I have is an external pump (pwms?) part # prd30768 that self regulates at 58 psi. Now I think I want to run a return line bc it’ll dump fuel right in the pick up tray which should aid in preventing starvation at super steep angles for prolonged periods of time.. Do I have to run a regulator with a return line? If I ran a factory style fuel pump in the tank, would I need a regulator for a return?
2. The instruction manual says you shouldn’t use hard lines and recommends running soft efi rated hose. To me I can’t see why it would be a problem if I had soft hose at the tank and tbi unit with factory hardline in between?
3. Is there an alternative o2 sensor I could use? The MSD branded sensors cost about $130-$150, but I can’t find any specs on it to try and find a suitable alternative. For example if I had to replace it would there be one I could go get from a parts store?

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HawK5 said:
Well I’ve been collecting parts and have come up with a few questions, got the tank and sending unit, still need to get the oxygen sensor.
1. I believe the fuel pump I have is an external pump (pwms?) part # prd30768 that self regulates at 58 psi. Now I think I want to run a return line bc it’ll dump fuel right in the pick up tray which should aid in preventing starvation at super steep angles for prolonged periods of time.. Do I have to run a regulator with a return line? If I ran a factory style fuel pump in the tank, would I need a regulator for a return?
2. The instruction manual says you shouldn’t use hard lines and recommends running soft efi rated hose. To me I can’t see why it would be a problem if I had soft hose at the tank and tbi unit with factory hardline in between?
3. Is there an alternative o2 sensor I could use? The MSD branded sensors cost about $130-$150, but I can’t find any specs on it to try and find a suitable alternative. For example if I had to replace it would there be one I could go get from a parts store?

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I am pretty sure you need a regulator regardless, without it you won't build the pressure, the excess goes back in the return
 
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