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DRIVING!!!
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Discussion Starter · #1 ·
Gentlemen,

I'm about to rivet the trunk panels... I will ---eventually--- have a carb'ed 351 or 408. I would like to utilize the ron francis harness fuel pump plug at the gas tank instead of letting it dangle while the fuel level sender is hooked up. Is there an intank fuel pump that will work with a carbed motor? Can I use a 'low presssure' intank pump with a regulator on the firewall?? Or do you guys suggest another method? Im ok with you guys saying mechanical or in line, just wanted you to know my preference prior. Any pics or part numbers would be awesome. Thanks again. Jeff
 

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I'll do this in 2 posts - first my choice:

Mechanical! reasons.....
1] simple

2] less expensive

3] tried true & k.i.s.s. [the last s is for Steve]

4] you can get a mechanical pump to flow what you need volume wise

Steve
 

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If going electric......

1] In tank 255lph pump is more then enough. we sell with the hanger for $225.00

2] 3/8 line both feed & return [more on this later]

3] Mallory regulator [It's the only one that will do this that we have found] $110.00

Why? Same k.i.s.s. principle as mechanical, OEM setup good for 100,000+ miles. Set it & forget it.

Why 3/8" both sides? Your asking a lot for the regulator to neck 45psi down to 5/7psi. The extra needs someplace to go & the larger volume line does that [even necking down to 5/16" at the tank] We have had people go 5/16" return but unless racing the fuel backs up to the regulator.

Steve

By the way we also do the 3/8 line & the fittings!
 

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make sure your sbf is set up for Mechanical pump @ the front cover and eccentric inside for pump.
i like mechanical
but there is this thing called vapor lock
i run an external pump but to each his own.
 

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I have a mechanical for my 408 with a 3/8" fuel line. Works great, easily replaced if needed and keeps up fine.
 

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Steve had set me up with option 2 and I like it a lot. I had actually thought about going mechanical until I saw a guy get vapor lock on an 80* night during a cruise up home. That was enough incentive for me.

The inertia switch is easy to grab on Amazon too if a vendor here doesn't have one inline, should you decide to go with the electric.
 

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Fuel pump ?'s

Gentlemen,

I'm about to rivet the trunk panels... I will ---eventually--- have a carb'ed 351 or 408. I would like to utilize the ron francis harness fuel pump plug at the gas tank instead of letting it dangle while the fuel level sender is hooked up. Is there an intank fuel pump that will work with a carbed motor? Can I use a 'low presssure' intank pump with a regulator on the firewall?? Or do you guys suggest another method? Im ok with you guys saying mechanical or in line, just wanted you to know my preference prior. Any pics or part numbers would be awesome. Thanks again. Jeff
Swabby: Mechanical is simple, cheap and easy to access, but prone to vapor lock if the fuel is hot. Because it pulls the fuel there is a slight vacuum in the line from the tank to the pump which may cause vapor lock in certain conditions.

Inline electric pumps are middle cost and can be put in an easily accessed postion close to the tank so maintenance is easy. If you switch to EFI later you can switch the pumps. Less chance of vapor lock as there is less fuel line from the pump to the tank. If you use an EFI pressure pump, you can use a regulator to reduce the pressure to carb levels and use a return line back to the tank.

Intank pumps are quiet, reliable but usually not available with pressure outputs that work for a carb. If the pump fails, they are hard to get to and expensive to replace. You can use an EFI pump in the tank and a regulator near the carb to drop the pressure. This option needs a return line. Again, if you decide to go to EFI later, the pump is already there.

My read is that the return line needs to be at least as big as the feed line. 3/8ths inch, -6 line will feed just about any engine up to 450-500 HP, past that you should probably go to 1/2 inch, -8 line. Any one of the option pumps will deliver 80 GPH or more. If you need more than that, you got one friggin big motor.

Just my way, but I used the EFI intank pump that shipped with my Fuel Safe cell, which puts out 65 PSI and about 100 GPH. I made an access plate in my trunk floor to allow me to replace any component in the tank. I have an Aeromotive regulator near the carb to get the pressure down to 8 PSI with -6 feed and return lines. If I hadn't already had the pump in the fuel cell, I would have gone with an inline pump near the tank and a regulator. Almost as simple as a mechanical and more flexible for future upgrades.

Aeromotive | 13301 - Universal Bypass Regulator

I only used the gauge to set the regulator pressure then removed it so if it failed it couldn't leak fuel in the engine compartment.

Ron

Ron
 

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my two cents...for entirely a different reason.

a mechanical pump just looks right in this car.

no offense to anyone, but the extra plumbing and a pressure regulator, with the absence of that pump hanging off the block, just seems out of place to my eye. i could say the same thing about 60's muscle cars with EFI.

i'm sure from an overall solution standpoint there are advantages for using more current hardware and technology. its just when the hood goes up i don't expect to see a "Resto-Mod".
 

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Interesting timing. I was just working on the Ron Francis wiring harness layout on my Mk4 build last night... While details aren't finally decided yet, I will be using a mechanical fuel pump and carb on the engine, same as my Mk3 build. So I was looking at the extra harness and plug for the in-tank fuel pump and the inertia switch which is also included and part of the harness. Right now I'm planning to just tie that stuff off and leave on the harness. I don't think would be a problem. If at some point I decide to go EFI (or a future owner) the hookups would already be there.

Haven't had an vapor lock issues with my Mk3 during the first season this year. And drove it during some pretty hot weather. 1800 miles and it never missed a beat.
 

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351W with carb and mechanical pump. My hard fuel lines are run away from heat as much as possible. I ran the car in some very hot summer heat with a lot of SC humidity. A couple of times the car took a little longer to start when very hot. I think that is from hot fuel in the carb, and is expected in that situation. Especially with the cr*ppy fuels we are forced to use.

My vote is for a mechanical pump for the reasons already posted.
 

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1] In tank 255lph pump is more then enough. we sell with the hanger for $225.00

2] 3/8 line both feed & return [more on this later]

3] Mallory regulator [It's the only one that will do this that we have found] $110.00

Why? Same k.i.s.s. principle as mechanical, OEM setup good for 100,000+ miles. Set it & forget it.

Why 3/8" both sides? Your asking a lot for the regulator to neck 45psi down to 5/7psi. The extra needs someplace to go & the larger volume line does that [even necking down to 5/16" at the tank] We have had people go 5/16" return but unless racing the fuel backs up to the regulator.

Steve

By the way we also do the 3/8 line & the fittings!
Sorry, partial hijack!

Dude you are not kidding about the big return line! So how do you recommend we get that all the way to the tank? Do we somehow port the return line into the fuel filler? My seems to be fine at 45psi, but it I try to run a carb I cannot get it down below 15psi.

Is this the only way to do it:
http://www.summitracing.com/parts/MOR-65385/
 

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DRIVING!!!
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307 Posts
Discussion Starter · #13 ·
Fellas,

Didn't these motors COME with mechanical pumps originally? in like a 68/69/70 mustang?? did they vapor lock?- never heard of a mustang vapor locking-- I had a 70 MACH 1 with a cleveland and it was a missile...

Is it just the design of the roadsters? insufficient cooling? misrouting of the fuel line? :confused1:
 

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I went mechanical. Safe, simple, inexpensive. Drove on several 90+ degree days this year with no vapor lock issues.

Ever see an electric fuel pump spray a 50psi stream of fuel on a fire? It is impresive!
 

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Sorry, partial hijack!

Dude you are not kidding about the big return line! So how do you recommend we get that all the way to the tank? Do we somehow port the return line into the fuel filler? My seems to be fine at 45psi, but it I try to run a carb I cannot get it down below 15psi.

Is this the only way to do it:
http://www.summitracing.com/parts/MOR-65385/
I recently converted from EFI to carb, and rather than try to run a bigger return line on a completed car, I used a combination of bypass regulator and deadhead regulator and kept the wimpy stock FFR return line. I have a 255lph pump in the tank and found the same as you....pressure drop on the return line all by itself is about 14-15 PSI.

I used an Aeromotive 13301 3-65PSI bypass regulator, adjusted to just above the return line pressure drop....about 16-18 PSI. Then, off the regulated port, an Aeoromotive 13205 5-12PSI carb regulator to deliver a rock-steady 6 PSI of fuel pressure to the carb under all conditions. Works perfectly. :beer:
 

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all are good options. Remember an external electric pump is really loud. If I had a street car I wouldn't want to have to listen to that all the time.
 

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all are good options. Remember an external electric pump is really loud. If I had a street car I wouldn't want to have to listen to that all the time.
Well, some are loud and some are quiet. I've run a Holley black pump that was pretty loud and a Holley HP125 that was really quiet. Once the engine was on you couldn't hear either one.
 

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2007 Calendar Cover Car
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For you mechanical pump guys, what are you using for the pickup? Granatelli, home made, older year Mustang pickup?
 
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