Posted on: July 30, 2016

by Ron Fraser in the March 2007 RootesReview:

From the Shop Manual I get the following information:

  • Flow rate = 15 gallons per hour
  • Fuel = 6 lbs/ gal 15 gal/ hour = 90 lbs/ hour
  • Pressure or delivery head = 48 in 48 in H2O = 1.73 psi

The convention is that at wide open throttle an engine uses about .5 lbs/ hr / hp; therefore:

  • 90 lbs/hr /0.5lbs/hr/hp =180hp

As you can see the SU is a low pressure pump working in the 2 psi range and will support up to around 200 hp, exactly within the rating for the stock 260 and 289. I have not confirmed this flow rate or pressure.

If you have an engine with a lot more than 200 HP or a carburetor that absolutely requires more than 2 psi you will need a different fuel pump with a higher flow rate and a higher pressure rating.

Some internet research indicates that the SU fuel pump can run up to 2.7 psi and flow 18 gal/ hr. Also indicated: these pumps are good for 75,000 to 100,000 miles before rebuild.

Personally I believe the SU pump is a very robust and reliable pump but the points are the weak link. An SU pump with solid state electronics would be much better, plus rebuild kits and parts are available.

(Ed. Note: electronic SU pumps are now available from Moss Motors among others.)

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