Currently running a carter strip mechanical pump feeding a 505 at about 525 hp. Adding new heads and cam and should be around 600+ hp when it's done. It's mostly a street car, but if I run it at the track I don't want to chance any fuel starvation. My guess is it would be running on the mechanical only prob 98% of the time

My thoughts are to add a carter electric pump on a switch near the tank for occasional use.
I've done this before on a different car with carter strip and Holley blue pump, but with and a bypass and check valve. I'm thinking id be ok with the less powerful carter electric pump without the bypass.

My questions for you guys...

Do you see this set up working without bypass/check valve?
Mechanical pump pull through the electric ok?
Regulator necessary?
Lastly, has anyone gotten away with just the carter strip mechanical pump in similar powered setups?

Thanks everyone

I have done this more than a dozen times with the carters. I put a momentary switch on the secondaries of the carb so when it they kick in it turns on the electric pump. When you get out of it it shuts off. Never have to worry about turning a toggle switch on or off.

Is the fuel flow of the mechanical pump alone sufficient for the new HP estimate? It's still the last restriction in the fuel system, regardless of whether you've got an electric pump backing it up.

Great idea!

I have exactly what you’re describing on my Satellite. I found that the Carter electric pump was not conducive to allowing the mechanical to draw through it. Sometimes it would allow flow, sometimes not. It seemed it just depended on where the electric pump settled when it was last turned off. So I ran a bypass line with a check-valve around it. Works perfectly. I have it on a rocker switch, and only use it to prime and at the track.
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I just run a holley red pump constantly with the mechanical . Also helps with when the fuel evaporates out of the carb and needs to fill the fuel bowls.

That's been my experience also, I'm always amazed when some claim to use them on an auxiliary basis.

I wonder how it works for some and not others? Maybe some electric pumps don't "park" in a way that would prohibit fuel flow through?

I've done it several times with no bypass. I used a Holley pump. The check valves on the electric pump should open easily from the suction of the mech pump.

One caveat: If the diaphragm in the mechanical pump ever ruptures, the electric pump will fill the crankcase with gasoline.

Other then noise what is the reason to not run an electric all the time? They have become more reliable and they work well. I used a holley blue for a very long time and put lots of miles on it, never a problem. Put some time and effort into mounting them and the noise is greatly reduced.

I'm not opposed to that. I've done both and if I was starting from scratch, I might do it all electric. I bought the car set up this way and the whole fuel system is brand new. The carter mech pump is simple and really works well. I've heard of some using the mech pump by itself in 600+ applications, and who knows when I'm going racing next. At this point, I'm probably more concerned about racing a 4 speed w the stock 8 3/4.

Thanks Joel. Holley red or blue?

It's not about check valves but about the design of the pump; some rotor designs don't allow through-flow and some only allow flow in certain rotor positions.

Besides the pump, your success will also depend on the lines feeding it. My Carter mech. wouldn't feed my 500" wedge with an 850 until I started experimenting with how long it took to fill a quart jug. Found 2 fittings that were really holding back the flow.

Replacing one and drilling out the other made a full 20% difference in volume. That worked well until I had the heads ported and stepped up in cam and installed a Dominator. Started running out of fuel on the big end again.

Installed a Holley electric pump actuated by a micro switch on the carb's secondaries and all is happy again.

So make sure that your fuel flow is not restricted any where and try the mech. pump to see if it will work.

You do have 3/8" lines and pick-up, don't you?

Thanks Dave. Yes,the lines and sender are 3/8", and they are factory reproductions. I'll look over the lines more closely, I think they are all factory bends and hopefully not kinked. Which Holley pump did you use? Did you use a pre filter? Where did you mount it? I was thinking of a red pump or carter electric.

My 540HP Street Hemi ran fine with a mech pump, Carter electric on the rear shock crossmember, and 1/2" and -8 line. Didn't have the electric on all the time, just for exercising it or for sustained freeway use. Just a simple switch under the dash.
Built it that way 33 years ago, still good.
I usually use the Holley blue for more power than that.
Like Dave says, I've also noticed some brands' fittings are smaller inside than others. The system will flow only what the smallest restriction allows it to flow.

Run the electric in parallel with a check valve, no more problem...

It's been a while, but I believe the pump is a Holley 140. I hung it on the rear shock cross member using a piece of tire sidewall. Kinda like some of our exhaust hangers. Eliminates most of the noise.

And I use a cheap regulator at the carb, just to be sure the pressure is not excessive. No additional filter before the pump, just the OE sock in the tank.