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| I am curious re. measured fuel pressure, spec'd, and https://slantsix.org/forum/viewtopic.php?t=24263 |
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| Author: | rock [ Sun Jul 29, 2007 9:54 am ] |
| Post subject: | I am curious re. measured fuel pressure, spec'd, and |
Hello folks, I am using a carbureted engine that has worked just fine with 1bbl, 2bbl and 390 and 500 cfm 4bbl carbs. Carbs are supplied with a new stock fuel pump through metal filter, up and over the valve cover in the suggested modification manner, through a new fuel pressure gage to carbs. Fuel is suupled through 5/16 braided steel line with AN fittings. My fuel pressure is a steady 2 psi. Volume output matches FSM pump test in a jar. . I understand why FI guys want more pressure, but I have read in many places that the carbs, particularly 4bbl, need 4 to 7 psi. So what gives...why do so many mfgrs spec 4 to 7 for their carbs? I must be getting the volume needed at 2 psi because up to nearly 90 mph there is no fuel shortage, so I have long been more focused on volume than pressure. Sure I can up pressure by using a smaller diameter line, but to what end? What pressure on a stock fuel supply are others operating at? rock '64d100 |
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| Author: | argentina-slantsixer [ Sun Jul 29, 2007 11:45 am ] |
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2 weeks ago a friend of mine replaced the fuel pump and got a weird pump that delivers 10 PSI  but LESS volume than the older pump wich worked fine (I told him NOT to try'n repair something that's working, but! ) same line, same everything, long story short, fouled plugs, the ammount of pressure was causing the needle/float assy to be open all the time, permitting the pump to flood the engine at idle.2 PSI at idle or in revs? |
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| Author: | SlantSixDan [ Sun Jul 29, 2007 12:27 pm ] |
| Post subject: | |
If you're getting the volume necessary but only seeing 2psi on the gauge, my best guess is an improperly-calibrated gauge. Factory spec on the slant-6 is 3-5 psi. |
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| Author: | slantzilla [ Sun Jul 29, 2007 12:32 pm ] |
| Post subject: | |
Is that flowing pressure or dead-headed with the needle closed?
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