[matt1840]

Ive got to the the fuel system setup so i can get this motor broken in..

Its currently a 461 olds completly fresh, large cam, tunnel ram dual edelbrock 750's (plan on getting holly 450's) Im debating on if i need an electric fuel pump or not to keep both carbs happy. i will be running the 750's this season.

I see the carter mechanical pumps put out 120 gph and top out at 6.5 psi, and the holly pump puts out 80 gph and tops at 8psi. I will be running a holly regulator to keep things even between the carbs.

The electric pumps are a bit pricey and i have limited mounting options, im hoping to get by with a mechanical considering im not "sucking down the fuel".

My fuel line comes out of the tanks at 3/8" and i plan on running that for the whole system



Any opinions???

 

[SS 201]

I run a Carter pump with a mechanical works fine. The Carter primes the system to minamize starts and keeps the fuel flowing.

 

[SmokinLowriderSS]

Ive got to the the fuel system setup so i can get this motor broken in..

Its currently a 461 olds completly fresh, large cam, tunnel ram dual edelbrock 750's (plan on getting holly 450's) Im debating on if i need an electric fuel pump or not to keep both carbs happy. i will be running the 750's this season.

I see the carter mechanical pumps put out 120 gph and top out at 6.5 psi, and the holly pump puts out 80 gph and tops at 8psi. I will be running a holly regulator to keep things even between the carbs.

The electric pumps are a bit pricey and i have limited mounting options, im hoping to get by with a mechanical considering im not "sucking down the fuel".

My fuel line comes out of the tanks at 3/8" and i plan on running that for the whole system



Any opinions???

Either pump will flow plenty of fuel, 3/8 line is plenty, no regulator needed, and I just don't like electrical fuel pumps, mechanicals are much more long-term reliable/require far less attention (meaning none).

Don't know what brand marine mech I run but I feed a single carbed 454, with 150 horse nitrous plate system off one big-azz mechanical fuel pump, through 3/8" line. 4.5 psi roughly @ 900RPM idle, 9 psi anywhere above 5-grand. Running pressure on the nitrous is unknown as wife has never held her foot in that so I can see, but the fuel pressure safety cutout does not opperate, so is plenty.
Told the marine dealer I wanted the biggest thing he carried, period. $150 later in 2003, plenty of fuel up to 6,000RPM on the gas.

Put a fuel filter BEFORE the pump, to keep tank crud out of it.

 

[matt1840]

no regulator needed.

Even with dual carbs no regulator is needed??? I thaught for sure id have to have one to keep both carbs fed the same amount at all times.

 

[rangerrob]

i run the same engine but with dual holley 4160 600 cfm carbs and a holley blue electric fule pump regulated at 6 psi. i just mounted it on the head and it ran fine last season.">http://s217.photobucket.com/albums/cc164/rangerranger25/?action=view&current=boat6014.jpg

 

[VDRIVERACING]

Mechanical is defintely the way to go. The pump manufacturer will tell you if you need a regulator.

You could go with a Holley/Carter/Edlebrock, etc. All good pumps; all come with regulator reccomendations.

 

[matt1840]

Mechanical is defintely the way to go. The pump manufacturer will tell you if you need a regulator.

You could go with a Holley/Carter/Edlebrock, etc. All good pumps; all come with regulator reccomendations.

THATS what i wanted to hear!!!


if i run the 6.5 psi carter it should be able to give me a solid 6psi at the reg at all times correct?? or should i get the 8psi holly just for piece of mind???

 

[SmokinLowriderSS]

Even with dual carbs no regulator is needed??? I thaught for sure id have to have one to keep both carbs fed the same amount at all times.

What are you gonna do, put the regulator in between the fuel pump & the carbs.
This way, you will still think you have the "lead" carb siphoning fuel flow from the "seccond" carb.
It's not happening.

Put it between them?
Then you have one carb getting less pressure than the other.

Run one pressure fuel line toward the carbs, split it to feed both carbs, use whatever fitting you want, a "T", a "Y", and feed both carbs.
Any difference in fuel suply to both will be miniscule, and unimportant.
Don't make one feed line 3 feet longer than the other of course, try to keep line lengths SIMILAR (exactly the same down to the milimeter is not needed)

Fuel pressure is related directly to flow allowed into the carbs. Once the carb bowls are full and they close off, excess fuel shows up as line pressure. As long as you can maintain suficient line pressure (excess pump output capacity under operating conditions, the carbs self-regulate fuel level, and flow into them.

Carburetors are self-operating. Feed them fuel under proper pressure, they will take in what they need, not what they do not.
Provide both carbs access to enough fuel flow under an acceptable pressure to heep them full, they maintain their own fuel level, the pump does not maintain fuel level. That is the purpose of floats, needles, and seats, to maintain a nearly constant fuel level under varying conditions. They work very well, have for a century.

 

[VDRIVERACING]

THATS what i wanted to hear!!!


if i run the 6.5 psi carter it should be able to give me a solid 6psi at the reg at all times correct?? or should i get the 8psi holly just for piece of mind???

Can't hurt to have abundant fuel! I like the way you think!!!

If you choose an 8 psi pump, you will need a fuel regulator. Magnafuel makes a four port regulator. One line in, four lines out. If your carbs only have a single inlet, they also make a two outlet model. You can get them through Jegs catalogue.

Here's some excellent gear at good prices:
http://claysmithcams.com/index.asp?PageAction=VIEWCATS&Category=254 - clay smith makes an excellent fuel pump for about $125... Buy direct from their website.

http://www.jegs.com/i/Magnafuel/665/MP-9633/10002/-1 - Magnafuel fuel regulator - top quality - about $140

This is hardware used in GN. Very high quality, simple to use, and won't let you down. Depending on the carbs you want, make sure you have the right regulator. Call Magnaflow with details; they have great CS...