Overflow valve...why not an adjustable bleed orifice or valve?

[Don M]

Why not CAN the overflow valve and install a homemade bleed orifice or valve that is adjustable!?! Seems like real world horsepower gains could come from not letting the dern fuel bleed away past the overflow valve. You could adjust the pressure to suit your needs.



Anyone got one under development? If not... . I may give it a thought over the next few weeks.



Don~

 

[Joe G.]

Probably not a good idea. Based on what I understand about how the injection pump works as long as it has sufficient fuel above a certain minimum pressure it will work correctly. Additional pressure won't help at all. A needle valve will not react to pressure like the overflow valves in our trucks. The fuel flow thru the valve will vary according to conditions. For example at low RPM and heavy load there will be less fuel flowing thru the valve than at high RPM and light load such as down hill coasting. A needle valve would not react correctly to these variations in operating conditions.

 

[Don M]

Sure it would work correctly... . but not optimum. If your overflow valve is letting fuel past... (like with a weak spring condition) your working but not working to full potential. My understanding is that weak overflow valve springs leak fuel back to the tank or fuel canister (whichever) This would cause airation in the fuel charge pushed through the injectors since the injectors push an area or piston full of volume. If this volume was more fuel and less air... . you would have more power.

Yes, the overflow valve is a good all around design. But.....

what would the damage be if ya just didnt bleed it as fast as the stock overflow valve does? Keep it in the pump at a higher pressure, say.



I was thinking more along the lines of an adjustable bleed valve that would be spring loaded. Something that could be tightend down to increase bleed off pressure. You could start off light and increase as needed. Needed say to drag race or pull out a good dyno run!!!





Don~

 

[illflem]

I've thought of using an adjustable pressure relief valve, they can be had for less than the overflow valve. Problem is by the time you finish the plumbing it would be more expensive. Stick with the stock valve, even though they wear out they are proven to work. Adding more pressure will get no better performance, it will just make your lift pump work harder wearing it out sooner.