...moving this discussion from Alessandro's EFI idle thread

Steve69 wrote:

Rufus68 wrote:

I'm running an Edelbrock 1403 carburetor sitting on a 1 inch phenolic spacer on a Summit aluminum intake.  I have an AEM 30-0300 AFR gauge providing the AFR reading.  I modified my fuel system to be a return style so that the fuel has a constant flow through the line to reduce heat buildup.  I did this using a Holley bypass regulator set at 5.5 psi.  I changed my mechanical fuel pump for an 8 psi higher flow pump to open the bypass regulator.  The stock fuel pump would not produce enough pressure to actually open the bypass.  And to further remove heat from the fuel line, I don't have it routed across the front of the engine.  It routes from the pump, back along the fender and then across the firewall before feeding the carburetor.  The bypass regulator with pressure gauge is mounted near the carb on the firewall.  I installed an inline electric fuel pump near the fuel tank wired to a momentary switch.  I use this pump to fill the line and carburetor before starting the car if it has been sitting for a while.  This prevents the excessive cranking of the engine needed to fill the carb while still allowing a mechanical fuel pump to be the normal source of fuel when the engine is running.

With the setup described above, my Mustang starts and runs fine.  I can tell by my AFR gauge that the Edelbrock carburetor can not be tuned to be at the ideal AFR under all running conditions and load.  That said, my current tune seems to be a good compromise.  For now, I'm happy to have a reliable car that I trust.
 

   Im kind of doing the same thing this winter on mine with this fuel filter.   $8 Cure For Vapor Lock - YouTube

 

Steve, I started with that setup but when I added an inline fuel pressure gauge I discovered that the pressure was less than 2 psi.  That is why I replaced the bypass filter with a bypass regulator.  After doing that, I discovered that the stock mechanical fuel pump did not generate the necessary pressure to open the bypass.  This is why I went shopping for a higher PSI mechanical fuel pump.  I found that the some of pumps made for the big blocks would produce 8 psi so that is what I installed.

Last edited by Rufus68 (7/29/2021 3:11 PM)