Fuel pressure-confussion

[jetrod]

Hey Guru's, The Ford "repair manuals " from the day, recommends a fuel pressure of 3 1/2 to 4 1/2 psi at the carb. The discussion on this site seems to to guide one to a MUCH lower pressure. What am I Missing?

[Terry,OH]

In what repair manual did you find the above Spec?

[marko39]

it is in the canada printed repair manual, got one a few years ago is very informative.

[Merc Cruzer]

Here it is, in my 53' Mercury manual

[jetrod]

I got the info from Fomoco owners manual and the Fomoco Ford 1949-50-51-52 F1 series trucks Shop Manual---Both are available as reprints. JR

[JM 35 Sedan]

Sponsored Links (Register now to hide all advertisements)

Originally Posted by jetrod

Hey Guru's, The Ford "repair manuals " from the day, recommends a fuel pressure of 3 1/2 to 4 1/2 psi at the carb. The discussion on this site seems to to guide one to a MUCH lower pressure. What am I Missing?

which year and make carburetor(s) are you using, or planning to use?

ps...I don't consider myself to be the Guru you refer to, but I have had some experience with stromberg carburetors used on early ford FH V-8's, and fuel pumps that provide way too much pressure.

[Bored&Stroked]

Keep in mind that in later years, there were no Stromberg 48s, 81s or 97s coming from the factory.

The Holley 94 style carbs can typically take the higher pressures - while the earlier Stromberg carbs like to see about 2 lbs max. Also, many of the current fuel-pumps that are sold as replacements have springs in them that generate ABOVE 4 lbs of pressure - which really screws up Stromberg (and sometimes Holley carbs).

I always run a low-pressure fuel regulator (with a gauge) to control pressure to the carbs. The low-pressure Holley one works pretty well.

The best situation is to have a "return line" back to the tank - so that the pressure regulator is not "dead headed" (where you tend to get pressure swings that spike due to the open/closing nature of the regulator).

The Holley pressure regulators do have a provision for a return line . . . which is the optimal configuration. (It goes BACK to the tank).

Almost all modern fuel systems (especially EFIs) have return lines from their pressure regulators. We do the same thing with high-volume racing fuel systems - we always have a return line. Sometimes we have electrical pump controllers as well (in or out of an ECU) - that adjust pump RPMs based on the pressure readings. These are used so that we don't "churn" the fuel too much and overheat it in the tank. This is also why you'll usually see fuel-coolers in the lines - to pull the "churn heat" out of the fuel as it circulates from/back-to the tank.

[jetrod]

MY Carb is a Holly 94 in an EAB stock 52 F1-The ford pump is putting out 31/2 to 4 PSI. JR

[Terry,OH]

The lower pressure Spec. is for the earlier Stromberg and Holley/Ford pre war about 2 to 2-1/2#. If your Ford document is for your vehicle year go with it. I don't see a conflict.

[Bored&Stroked]

Originally Posted by jetrod

MY Carb is a Holly 94 in an EAB stock 52 F1-The ford pump is putting out 31/2 to 4 PSI. JR

You should not have any problems with that pressure with a Holley carb