I have a similar thread over in the cast iron 2000 thread, mostly containing anecdotes and philosophy. I promised the mods not to foul the air over there with too much mechanical stuff, so that order can be maintained.
Anyway, I finished the fuel pump replacement today, and finished sorting the engine with it running sweetly. More on that later.
Off and on, discussion comes up about replacements for the 3-port fuel pump. I previously did this for the two pumps on my Montreal. This single pump was much easier.
First, I rejected the idea of using an L-jet pump, as this typically requires reducing the size of the return line restrictor hole. While this can help keep the pressure up around a good number, it reduces the cooling of the Spica pump via the flow-through fuel. Long term impact? I’d rather not test it.
So, I bought an off-brand version of the Bosch -044, which is a high-pressure, high-flow unit. I also bought a Holley pressure regulator, and a handful of fittings, most of which I already had in stock from my aircraft maintenance work.
Some of the pluses are that everything bolts into the existing pump and filter brackets, the fuel connection points are very close to where they were with the three-port, and all of the nipple sizes allowed the use of standard hose in matching sizes.
As the pump has an overall greater output than required, the regulator allows for a quite linear pressure control all the way from idle to full power. When I first tested the assembly, I was getting 21-22 PSI at idle, with the regulator screwed all the way to minimum. So, I drilled the restictor out to .093”, screwed in the regulator a little, and bingo, dead on 16.5 PSI from idle up. As I’m now within the adjustable range of the regulator, I can correct if future testing proves it necessary.
And, I’ve increased the flow through, improving the cooling of the Spica pump.
Total.. around $150
Anyway, I finished the fuel pump replacement today, and finished sorting the engine with it running sweetly. More on that later.
Off and on, discussion comes up about replacements for the 3-port fuel pump. I previously did this for the two pumps on my Montreal. This single pump was much easier.
First, I rejected the idea of using an L-jet pump, as this typically requires reducing the size of the return line restrictor hole. While this can help keep the pressure up around a good number, it reduces the cooling of the Spica pump via the flow-through fuel. Long term impact? I’d rather not test it.
So, I bought an off-brand version of the Bosch -044, which is a high-pressure, high-flow unit. I also bought a Holley pressure regulator, and a handful of fittings, most of which I already had in stock from my aircraft maintenance work.
Some of the pluses are that everything bolts into the existing pump and filter brackets, the fuel connection points are very close to where they were with the three-port, and all of the nipple sizes allowed the use of standard hose in matching sizes.
As the pump has an overall greater output than required, the regulator allows for a quite linear pressure control all the way from idle to full power. When I first tested the assembly, I was getting 21-22 PSI at idle, with the regulator screwed all the way to minimum. So, I drilled the restictor out to .093”, screwed in the regulator a little, and bingo, dead on 16.5 PSI from idle up. As I’m now within the adjustable range of the regulator, I can correct if future testing proves it necessary.
And, I’ve increased the flow through, improving the cooling of the Spica pump.
Total.. around $150