Larry Shepherd’ Mopar Small Block Engines book says keep mech fuel pump when adding electric.

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Spadman

Spadman

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Shepherd says the mech pump will function as a pressure regulator. What’s the story on this?
 
Well I believe he said that back in the 1970s when there weren't electric pumps available like today. In addition, I also believe the stock pump was intended to work as a regulator too.

Nowadays lots more better electric pumps, and not heating the gas from mech pump block contact, out ways any reason to run a mech pump on a race car. Though for a street car I just run a good stock type mech pump.
 
Partially true. Many do not understand how a mech pump works. the arm does not pump gas, it rather, cocks the arm on the spring. The spring is what pumps the fuel. When the thing pumps up to pressure on a closed needle and seat AKA at idle, the arm floats on the cam for a stroke - or - a few. So the spring determines pressure.

But if the electric is already putting out more pressure than than the mech pump, then the electric will be the determining pressure. The electric will just blow fuel right through
 
This is a 2016 book. He is talking a performance street engine. He says use a regulator if the mechanical pump is removed. Page 124-125 of How to build Max Performance. I’m having to put in a new fuel tank and want to use a tank mounted pump while I’m at it. The reason is that I’m doing conventional carbed small block for now but want all future options open all the way to a modern hemi 392. I don’t want to mount a regulator near the carb and spoil the stock appearance. I’m thinking I could simply connect the return at the mechanical pump. Another option I’m thinking about is a regulator near the tank.
 
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Spadman said:
This is a 2016 book. He is talking a performance street engine. He says use a regulator if the mechanical pump is removed. Page 124-125 of How to build Max Performance. I’m having to put in a new fuel tank and want to use a tank mounted pump while I’m at it. The reason is that I’m doing conventional carbed small block for now but want all future options open all the way to a modern hemi 392. I don’t want to mount a regulator near the carb and spoil the stock appearance. I’m thinking I could simply connect the return at the mechanical pump. Another option I’m thinking about is a regulator near the tank.
Click to expand...
It's a 2016 reprint. The information is dated.
 
So what do you think about the pump in the tank and a regulator with return; and it’s best placement?
 
I prefer the regulator as close to "whatever" mixer you're using. Use the regulator in the return line to act as the return orifice. Is that what you're asking?
 
The hide it by the fuel pump. Who is going to see it down there.
 
If you are going to use an electric pump, I would just remove the mechanical one.
Put a block off plate, where the mechanical one was, and mount the regulator to the block off plate.
 
Doesn't want to spoil the stock appearance but is considering a modern Hemi swap for the future. This strikes me as slightly humorous. :lol:
 
I can see the humor in that. I don’t even understand myself most of the time.
 
That's an old racers track from the 80s I think it was in somewhere in a direct connection manual also
 
Heck you could just knock the arm off the mechanical fuel pump, put a block off plate behind it, and run the fuel line right through it pumping with an electric.
 
I run an American made Carter P4594 electric pump along with an NOS Fram HPG-1 right off the tank. Fuel line from pickup to carb is 3/8”, no fuel delivery issues running the 1/4 mile at 114mph. I run a billet Holley regulator even though with that particular pump it’s not really required. The psi of those pumps show 5-9 psi, I can’t recall what psi I saw without the regulator but I had to dial in some regulation to keep it at about 5.5 or 6 IIRC. Depending on carb and electric pump you use you might not even need a regulator.
 
Thanks 12many; and all who responded. My issue is that I’m way behind the times. I built this 360 in the eighties and have never run it. Now that the car is finally getting the body finished I want to run the 360 a bit but I know I won’t be satisfied with it long term. I’m already collecting parts for a 340 build but it’s not numbers matching anyway so I don’t know what might end up in that engine bay. In the meantime, as long as I’m using the 360 I want to keep it day two in appearance. It’s got old slotted mags, headers, and TA radials. Just what I would have had back then if life hadn’t gotten in the way. The car is a 1970 340 Dart btw.
 
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