Fuel pressure-confussion
- Thread starter jetrod
- Start date
Merc Cruzer
Well-known member
JM 35 Sedan
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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.
Last edited:
Bored&Stroked
Well-known member
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.
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.
Bored&Stroked
Well-known member
You should not have any problems with that pressure with a Holley carb