Carter Mechanical Fuel Pump?

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SSing

SSing

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#1 One particular fuel pump has 1/4" NPT inlet/outlet. With a 3/8" fuel line from the fuel tank, I´m sure this doesn´t mean what I think it means. 1/4" sounds tiny.
Question #2 One Company rates a fuel pump free flow 43 GPH. Another Company says same pump has 120 GPH, but not in what rating. Are there different ways of measuring fuel flow here?
Help me understand this,
thank you, Stefan
 
SSing said:
#1 One particular fuel pump has 1/4" NPT inlet/outlet. With a 3/8" fuel line from the fuel tank, I´m sure this doesn´t mean what I think it means. 1/4" sounds tiny.
Question #2 One Company rates a fuel pump free flow 43 GPH. Another Company says same pump has 120 GPH, but not in what rating. Are there different ways of measuring fuel flow here?
Help me understand this,
thank you, Stefan
Click to expand...
Yep, the NPT or pipe thread sizes are strange. 1/4" npt is a tick over 1/2". Here's a chart. Determine pipe thread sizes
 
because it's a different pump, m6903 is 120 gph
 
What are you feeding? What is your engine combo?
 
toolmanmike said:
What are you feeding? What is your engine combo?
Click to expand...
This... I run a clone of the 360 Magnum clone, 380 horsepower... I run the Carter M6270 with a half inch inlet line to the pump, with a three eighths inch line, outlet to carb... The fuel pressure gauge , reads 5.5 pounds of fuel pressure , with an unadjusted Holley fuel pressure regulator...on a Holley 750 double pumper... Are you running stock 273/318/ 360 ? ..Or do you have some camshaft , head work , and headers ,... involved.?.
 
toolmanmike said:
What are you feeding? What is your engine combo?
Click to expand...

Well I´m trying to recreate a ´68 SS/B Barracuda. And except for a bigger camshaft, it´s all there.
Originally I think the ´68 Hemi A-bodies came with the Carter 4024. There are several letter combos to this pump, like S and M, and I don’t know if Pumps are different.
In the early seventies Direct Connection offered the 255118 Pump, which is the 4024. In 1975 DC offered the P4007039 which is the M4862. This pump flows some 80 PGH, and is the one I´m going to choose, although the 4024 may be more correct in my application. Two Bendix Electric Fuel Pumps will feed the mechanical pump through a 3/8” fuel line.
The M6903 Pump flows 120 PGH which I thing would be overkill.

But my concern is I don´t get the difference in fuel flow in the same pump, the M4862, that different sellers list. (See post above). Must be a different way of rating the flow?
Thank you for helping me on this…
 
Abodybomber said:
This... I run a clone of the 360 Magnum clone, 380 horsepower... I run the Carter M6270 with a half inch inlet line to the pump, with a three eighths inch line, outlet to carb... The fuel pressure gauge , reads 5.5 pounds of fuel pressure , with an unadjusted Holley fuel pressure regulator...on a Holley 750 double pumper... Are you running stock 273/318/ 360 ? ..Or do you have some camshaft , head work , and headers ,... involved.?.
Click to expand...

Well see above, and see if you can explain the difference in how the same Pump has different flow...
Thank you.
 
SSing said:
Well I´m trying to recreate a ´68 SS/B Barracuda. And except for a bigger camshaft, it´s all there.
Originally I think the ´68 Hemi A-bodies came with the Carter 4024. There are several letter combos to this pump, like S and M, and I don’t know if Pumps are different.
In the early seventies Direct Connection offered the 255118 Pump, which is the 4024. In 1975 DC offered the P4007039 which is the M4862. This pump flows some 80 PGH, and is the one I´m going to choose, although the 4024 may be more correct in my application. Two Bendix Electric Fuel Pumps will feed the mechanical pump through a 3/8” fuel line.
The M6903 Pump flows 120 PGH which I thing would be overkill.

But my concern is I don´t get the difference in fuel flow in the same pump, the M4862, that different sellers list. (See post above). Must be a different way of ratingtv the flow?
Thank you for helping me on this…
Click to expand...
I owe you, an apology..Stephan...I will step out of the way... Step 2, threw me ,off course.. Hopefully, Hemi Mark, Andy F, throw their hat, in the ring.. Sounds. like a bitchin' build... Best, of luck...
 
Abodybomber said:
I owe you, an apology..Stephan...I will step out of the way... Step 2, threw me ,off course.. Hopefully, Hemi Mark, Andy F, throw their hat, in the ring.. Sounds. like a bitchin' build... Best, of luck...
Click to expand...
Absolutely not. And I was so focused om my question I neglected your description too... :)
 
Yes thanks, but what differs 43 PGH "free flow rate", from 120 PGH?
Oh... doubled that...
 
Sometimes it's a misprint that everyone copy's because they don't know any better.
If you want the real answer call the manufacturer and if you don't like the answer the girl on the phone gives you ask for her manager.
 
brian6pac said:
Sometimes it's a misprint that everyone copy's because they don't know any better.
If you want the real answer call the manufacturer and if you don't like the answer the girl on the phone gives you ask for her manager.
Click to expand...

Yes, could be the case...but I think this expression "free flow rate" is a different way of measure flow, since it´s written behind the 43 GPH figure, but not 120 GPH
 
well pipe id , is how pipe is measured . and tube is measured on its od . so given wall thicknesses for tubing . there very equal in size . the restriction is the line to and from the pump , if there is less room the pump can't get the volume , that it could if the size was larger for more room , pump will still make the same pressures in either .
 
pomonamissel said:
well pipe id , is how pipe is measured . and tube is measured on its od . so given wall thicknesses for tubing . there very equal in size . the restriction is the line to and from the pump , if there is less room the pump can't get the volume , that it could if the size was larger for more room , pump will still make the same pressures in either .
Click to expand...

Yes, and to me this would mean the "free flow" numbers would be higher, not like in this case lower...
 
So I called carter tech line Contact Us
Email & phone # are on this page.
Summit ad m4862 strip super pump 43gph 8-9.5psi
Summit ad m6903 street super pump 120gph 6-7.5 psi
Tech line person could not answer my questions, why is street pump 120, strip pump 43?
told me 120 is rated at 0 psi and 43 is rated at pressure was his best guess??
He told me the only difference between the two pumps is pressure again his best guess??
Hell of a tech line
 
brian6pac said:
So I called carter tech line Contact Us
Email & phone # are on this page.
Summit ad m4862 strip super pump 43gph 8-9.5psi
Summit ad m6903 street super pump 120gph 6-7.5 psi
Tech line person could not answer my questions, why is street pump 120, strip pump 43?
told me 120 is rated at 0 psi and 43 is rated at pressure was his best guess??
He told me the only difference between the two pumps is pressure again his best guess??
Hell of a tech line
Click to expand...

:) thank you. Yes like you say -hell of a tech line... again, 43 PGH free flow is rated at pressure?
Well I´m sure there are an explanation somehow...
Thanks for taking the time.
 
i know that the carter 6903 was mopar performance supplied pump for street/strip as well . that the one i just installed on a mild 340 . it gets my vote . the 4862 is to much pressure for the thermo carbs . and for most street carbs as well .
 
pomonamissel said:
i know that the carter 6903 was mopar performance supplied pump for street/strip as well . that the one i just installed on a mild 340 . it gets my vote . the 4862 is to much pressure for the thermo carbs . and for most street carbs as well .
Click to expand...

Ok... so what do you say, I´m using the Holley´s 4235-36 on the Cross Ram on my Hemi. 770cfm and carb is based on the Holley #4160 I think... This Carb doesn´t like to high pressure. I don´t use any regulator. Is 6psi to high you think?
 
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