351 Windsor - Mechanical Fuel Pump versus Electric Fuel Pump?

[DriftingCloud]

My Holley Red Fuel Pump just died. I did actually make it home, however, so no complaints. It was 11 years and 9,800 miles old.

In thinking about replacing it, I actually like the idea of a mechanical fuel pump better than another electric fuel pump. I was hoping to solicit some comments from people who are running mechanical fuel pumps on their 351 Windsors.

My main area of concern is I'm using the front oil cooler and the two oil lines leaving the block would seem to interfere with where the mechanical fuel pump would mount. They are lower, but not by much (see image).

Thanks for any advice...

[madmaxx]

If at all possible go with mechanical. Electrical SUX. They are noisy, at times loose their prime, I loathe electrical ones so NOISEY!!!!

[DriftingCloud]

You've clearly described my Holley Red... LOUD!

Aside from that, I just think the mechanical ones are simpler and safer. No engine, no fuel flow.

[Sydney]

I have the same Canton adapter that your picture shows. I had to turn it 90 degrees toward the ground and put 90 degree fittings on the hoses. That gave enough clearance for the hoses to run under the fuel pump.

[DriftingCloud]

Excellent. Thanks! Did you build it that way or convert it from an electric fuel pump? Any chance I could see pictures of your setup?

[Pete Munroe]

You said you were able to nurse the car home...I assume there was some flow of gas?

Have you taken off the plate on the bottom? There is a filter screen that can get plugged up if some garbage gets into the fuel. You can carefully slip it out and clean it without tearing it up.

The pump impeller vanes are replaceable...also there is a pressure relief valve that perhaps is stuck open. Pretty sure Holley sells a basic rebuild kit that includes new impeller vanes.

When you take it apart, proceed slowly and the gasket is reusable...also you will see it gets imprinted with the fuel passages, so it should go back on the same way it came off.

They maybe noisy, but fixing the electric one that is already installed is probably easier than plumbing in a new mechanical pump.

If the electric motor is dead or groaning and turning slowly (worn out brushes?) probably out of luck.

[DriftingCloud]

Yes, there was some flow of gas, but my fuel pressure gauge was reading close to zero. Normally, it's about 6-ish psi. Occasionally, the fuel supply was obviously zero (even without the gauge) as I'd quietly coast to dead stop. I'd turn everything off, sit for few minutes, and try again. Four bouts of that finally got me home (I was only about 10 miles away).

The overall pre fuel pump filter is relatively new. I did remove the bottom plate of the Holley Red. There was nothing obvious going on in there. The fuel pump is making a worse than usual noise. Groaning and a little variable is the best description.

I agree about the replumbing task being more difficult than just replacing the electric fuel pump, but the failure got me thinking. Sometimes my mind is just happier with one philosophical approach over another. I keep leaning towards the simplicity and safety of the mechanical fuel pump, so I was just curious how others have solved the Canton adapter and oil lines being in the way.

[wkooiman]

I prefer mechanical too. I hate the whirring of the electric. The only way I'll go back is if I do EFI, and then I'll try for an in-tank pump. That would be on a non-Cobra, though. My Cobra will always have carbs.

[lippy]

If a mechanical can provide enough flow, it's simpler, cheaper, and more reliable. I'd say below 550 HP or so mechanical should be fine. One advantage of an electric though is quicker starting because you can fill the bowl before starting the engine.

[Sydney]

Excellent. Thanks! Did you build it that way or convert it from an electric fuel pump? Any chance I could see pictures of your setup?

I built it that way. I did just replace my 10 year old Napa pump with an Edelbrock 1725 unit a couple of months ago. Hard to tell in the pic, but the oil lines are right under the fuel pump.




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[Tommy]

I'm old enough to have driven many miles in daily drivers with mechanical fuel pumps. I don't recall ever having one fail. That said, I went with an electric fuel pump in my Cobra for two reasons. First, when the weather gets cold, it may sit for a month or more between starts. I like knowing the float bowl is full before I press the start button so I don't work the starter and spin a dry engine too much. Second, my engine has a racing modified carburetor with no choke system. It needs a full shot of fuel to compensate for the large volume of cold air at start.

My electric pump is noisy, but then so is everything else in this car. The Red Holley has an internal fuel pressure relief valve that limits the flow of fuel to the carburetor by redirecting some of the pumped fuel back to the intake side of the pump. That means when the engine is not demanding a lot of fuel, the pump is repumping the same fuel over and over. So, instead of taking heat from the pump away to the engine, the fuel will allow the pump to run hotter. Putting a fuel pressure regulator (with a return line to the tank) downstream from the pump will solve that problem and likely allow the pump to last longer. If you do that you'll either need to use a pump without an internal pressure regulator or one that allows a pressure setting higher than the one on the external fuel pressure regulator.

[bkozlow]

Replace the electric pump. Add the mechanical, problem I see is that the engine may have not been setup for a mechanical pump. Pull off the pump cover and see if you have the pump cam on the crank. If not then a bigger job of pulling the front of the engine off and adding one. A lot of engines are built without the fuel pump cam these days with everyone going to all electric pumps. Electric-mechanical gives you an extra layer of protection on pump failure and provides a constant fuel supply to the mechanical in high RPM situations.

Bill K

[DriftingCloud]

Originally Posted by Sydney

I built it that way. I did just replace my 10 year old Napa pump with an Edelbrock 1725 unit a couple of months ago. Hard to tell in the pic, but the oil lines are right under the fuel pump.

Thanks! That helps.

[DriftingCloud]

Originally Posted by wkooiman

My Cobra will always have carbs.

Ha ha... Yes. Back to my mind is just always happier with one philosophical approach over others. I understand all the advantages of EFI over carbs, but to me, carbs are right on a Cobra. If I wanted all the conveniences of a modern car, I wouldn't have my Cobra.

[DriftingCloud]

Originally Posted by Tommy

First, when the weather gets cold, it may sit for a month or more between starts. I like knowing the float bowl is full before I press the start button so I don't work the starter and spin a dry engine too much.

Lippy made this point, too. I hadn't thought about that much yet. Mine can sit for a while as well. I am running an electric choke on my Holley Double Pumper, but it still needs fuel to start. The faster that's received the less wear and tear on the engine during a relatively dry crank.

Originally Posted by Tommy

My electric pump is noisy, but then so is everything else in this car.

Fair point, and I'm still laughing at the simplicity of this. There's no subtly to a Cobra. I guess my issue is with noises I like versus noises I don't. Ha ha...

Originally Posted by Tommy

The Red Holley has an internal fuel pressure relief valve that limits the flow of fuel to the carburetor by redirecting some of the pumped fuel back to the intake side of the pump. That means when the engine is not demanding a lot of fuel, the pump is repumping the same fuel over and over. So, instead of taking heat from the pump away to the engine, the fuel will allow the pump to run hotter. Putting a fuel pressure regulator (with a return line to the tank) downstream from the pump will solve that problem and likely allow the pump to last longer. If you do that you'll either need to use a pump without an internal pressure regulator or one that allows a pressure setting higher than the one on the external fuel pressure regulator.

I didn't know that about the redirection. No wonder they don't last very long absent a fuel pressure regulator and tank return line. Heat build-up in a fuel pump seems like a fairly bad idea.

[DriftingCloud]

Originally Posted by bkozlow

Problem I see is that the engine may have not been setup for a mechanical pump. Pull off the pump cover and see if you have the pump cam on the crank. If not then a bigger job of pulling the front of the engine off and adding one. A lot of engines are built without the fuel pump cam these days with everyone going to all electric pumps.
Bill K

Thanks! I just assumed there would be a pump cam. I now have a project for today...

[DAVID GAGNARD]

I had the exact same remote oil cooler block on my race car with a mechanical fuel pump and no problems........I used a Carter street/strip fuel pump......

At worst,you'll have to change the fitting on the cooler adapter on the engine from straight to 45 degree or 90 degree,I think I had 45 degree on mine, but you can turn the adapter slightly downward and it may clear depending on the pump you use......

BTW: I don't like electric fuel pumps either........

good luck...

David

[joyridin']

Why not do it right and put an electric pump in the tank like a FI car? You can buy a low pressure pump and an adapter from Tanks Inc. and hook it up easily. They are quiet, efficient, and hassle free. Thousands upon thousands of EFI cars run them without problems.

I would not use an old Holley red. They sound like a 50 year old meat grinder.

[lippy]

I know electric pumps are noisy but these are Cobras. I don't even hear mine.

Anyway, forgot to provide more details on my setup. The pump is a Weldon and it's guaranteed for life and rebuildable. More expensive but the internals are all metal and it's among the best pumps you can buy. Since my engine puts out 640HP, I ran AN8 Aeroquip Teflon/braided hose and two large billet filters - one at the tank and one up front. I have a bypass regulator at the pump that recirculates to the tank, and a standard regulator up front under the hood. Insulated everything under the hood. Also installed a separate fused power line run through McMaster-Carr heat/oil/abrasion resistant conduit, and a Ford inertia switch in the trunk. Also added a hidden fuel pump cut off switch under the dash so I can cycle the pump to fill the bowl and shut it off with the key on.

[RET_COP]

If my Cobra has been sitting for some time and the bowls are dry, (usually during the off season) I squirt some gas in the vent tubes and have instant fuel to the accelerator pumps. Takes an extra few minutes but it works.