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fuel pressure

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401fanatic View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote 401fanatic Quote  Post ReplyReply Direct Link To This Post Topic: fuel pressure
    Posted: Feb/11/2019 at 12:26pm
Fresh 401 modified and about 5 hrs on it now. When it sits for a while I loose fuel pressure prime. It cranks a very long time before I see fuel in my sight glass at the carbs.  New carter street strip mechanical pump. Once I get fuel to the carbs it runs great. Why am I loosing prime all the way back to the tank?
74 javelin 401 t-10 3.91 twin grip.
74 javelin 401 998 3.54 twin grip.                            
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Trader View Drop Down
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Post Options Post Options   Thanks (1) Thanks(1)   Quote Trader Quote  Post ReplyReply Direct Link To This Post Posted: Feb/11/2019 at 12:36pm
It's more likely your fuel is evaporating in the carburetor, and without knowing your pump, fuel vapor pressure is building in the fuel line to the carburetor and possibly the line under the car (depending on exhaust pipe run), pushing fuel back to the tank.
Your tell on this is the empty sight glass.
Start it up from cold and run for 2 minutes and shut down, hood open. If the sight glass still has fuel, it's a temperature problem. If the sight glass goes empty then you have a fuel pump problem.
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401fanatic View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote 401fanatic Quote  Post ReplyReply Direct Link To This Post Posted: Feb/11/2019 at 12:55pm
It would be a temp problem then. I’ll lol into it a little closer. Thx.
74 javelin 401 t-10 3.91 twin grip.
74 javelin 401 998 3.54 twin grip.                            
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PHAT69AMX View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote PHAT69AMX Quote  Post ReplyReply Direct Link To This Post Posted: Feb/11/2019 at 1:21pm
Today's Gasoline?... Pass Side Exh Heat Riser in place?... Blocked off Intake Heat Crossover?
Modern aftermarket import offshore Fuel Pump?... Fuel Pressure Gauge?...  Regulator?...
What Carburetor?...  Cast Iron Intake?...  1" Phenolic Carb Spacer?...


Edited by PHAT69AMX - Feb/11/2019 at 1:25pm
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401fanatic View Drop Down
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Post Options Post Options   Thanks (1) Thanks(1)   Quote 401fanatic Quote  Post ReplyReply Direct Link To This Post Posted: Feb/11/2019 at 1:40pm
new carter street strip mechanical pump. New carter 500 cfm carbs calibrated for duel quad applications. 93 octane pump gas. Headers. Cross over blocked. Offy aluminum duel quad intake. No Spacers. Generic fuel pressure guage. 
74 javelin 401 t-10 3.91 twin grip.
74 javelin 401 998 3.54 twin grip.                            
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401fanatic View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote 401fanatic Quote  Post ReplyReply Direct Link To This Post Posted: Feb/11/2019 at 1:41pm
no regulator. 6 psi. 
74 javelin 401 t-10 3.91 twin grip.
74 javelin 401 998 3.54 twin grip.                            
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401fanatic View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote 401fanatic Quote  Post ReplyReply Direct Link To This Post Posted: Feb/11/2019 at 1:48pm
Edelbrock carbs. My bad. 
74 javelin 401 t-10 3.91 twin grip.
74 javelin 401 998 3.54 twin grip.                            
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Trader View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Trader Quote  Post ReplyReply Direct Link To This Post Posted: Feb/11/2019 at 2:02pm
Running hose and not metal lines can be more beneficial to fuel evaporation. Not as pretty.
Re-routing the fuel lines to the fender wells, or with two carbs, run tight against the carburetors and then away from the heads at the front of the engine.  Run the lines on a down slope. Shield from exhaust pipes and hot surfaces. 
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Post Options Post Options   Thanks (0) Thanks(0)   Quote PHAT69AMX Quote  Post ReplyReply Direct Link To This Post Posted: Feb/11/2019 at 2:05pm
Agree with Trader, need to do something to determine if Heat or Pump related.
Confidence with modern aftermarket parts is dubious, and modern fuel formulation.
Does Indiana go with different "Winter Formula" fuel ?
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401fanatic View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote 401fanatic Quote  Post ReplyReply Direct Link To This Post Posted: Feb/11/2019 at 2:19pm
I’m shooting from the hip and assuming it is heat related. Pump seems fine and at least 6 psi. Winter formula in southern Indiana is something I’ll have to check into. I don’t know.  Worst case I could go with a electric pump and prime before starting but I’ve never really cared for electric pump wine noise.
74 javelin 401 t-10 3.91 twin grip.
74 javelin 401 998 3.54 twin grip.                            
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