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Hi, I Have a 68 FE390 with a Holley 780 carb with vacuum secondaries. The carb has just been proffesionally overhauled. When the engine has warmed up and under steady rpm the car starts to sputter but when I give it some gas no problem, good acceletation and no sputtering under load. When I slow to turn a corner and when accelerating out of a corner the car sputters and cuts out under acceleration. When stopped and revving no problem. Any Ideas?
 

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Hi, I Have a 68 FE390 with a Holley 780 carb with vacuum secondaries. The carb has just been proffesionally overhauled. When the engine has warmed up and under steady rpm the car starts to sputter but when I give it some gas no problem, good acceletation and no sputtering under load. When I slow to turn a corner and when accelerating out of a corner the car sputters and cuts out under acceleration. When stopped and revving no problem. Any Ideas?
You stated that you had the carb professionally rebuilt but not professionally installed. This sounds like the idle mixture screws were not adjusted properly and perhaps the accelerator pump as well.

Its not a complicated set-up and something that you should be able to do yourself after reading the how-to out of a good repair manual.
 

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Float level CORRECT. You stated that acceleration is ok so those circuits should be ok. Most issues when in the turns is float level issues. The 780 Holley is the easiest carb in the world to tune and rebuild. They have BEEN around for ages. Now what power valve is installed in it??? What is the jet size?? And does it have a RIO pump?? this is all things that have to be known to answer your question. Carbs should be tuned on the car. Not just rebuilt!!
 

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Could be float level ( sounds like it's too high), clogged fuel filter or line, faulty fuel pump.
 

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Could be float level ( sounds like it's too high), clogged fuel filter or line, faulty fuel pump.

Yes sounds like the old SPILL OVER in the turns. You know when the floats are to HIGH the gas spills over into the engine.

DUDE we are showing our AGES here Thats scary.(We actually worked on those things called CARBS)Actually saw your profile you are a young Guy compared to me. I am an old DUDE. I know that every morning when i have to take a TAXI to the BATH ROOM when i wake UP. Peace Tom

:bigthumbsup:bigthumbsup:bigthumbsup
 

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Does this happen with a full tank of gas? Pick up in tank bent? Make sure fuel line isn't being crimped or pinched when motor torques. Check motor mounts too. Is there anything flopping or laying on one of the coil wires at coil during a turn caused by G-force? Wiggle test the coil wires. This has happened to me.
 

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Discussion Starter #7
68 Mustang misfiring

Thanks guys for all your replys. However, I found out what the problem was. The choke was set up incorrectly. Cold off/Hot on

What was happening when the engine was cold no problem, when it warmed up it was running excessively rich, that was why when i slowed to a corner or sat at lights at idle it would sputter when i took off.

Cleaned the plugs and disconnected the choke and all sweet now.
 
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