454 stuttering/hesistate under steady speed - Hot Rod Forum : Hotrodders Bulletin Board
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Old 05-05-2010, 11:11 AM
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454 stuttering/hesistate under steady speed

When i first fire up the car it will work fine. After warm up and cruising around @ 165-180* i will be driving down a road at just about any steady throttle speed and the car will start to hesitate/stutter. If i put the hammer down a little it will pick up and go. Then it will go back to its previous state.
Fuel pressure is at 6.5-7psi, oil pressure is between 50-65 while cruising about 35 at idle after its warmed up.
If i shut the car off for a few minutes and start it back up it seems like i have to give it a couple throttle pumps before it will fire back up. It doesnt start as easily as it does when its cold. Im pulling about 11in of vacuum at idle. 900-1k rpm. Thats with about 1 turn out on all 4 corners of the carb. Cam isn't very aggressive 230/230 @.050 I gave it another 1/4 turn out thinking maybe it was starving for fuel but it didnt seem to help.

Ideas?

Timing? Valve lash?
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Old 05-05-2010, 03:22 PM
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Possible Carb Adjustment In Order.

Sounds like the carb might be flooding the plugs. is fuel mixture rich? smell fuelish. If you can obtain a digital rpm meter, attach and begin with front bowl adjustments. close the needle valve slowly and observe rpm. if rpm rises keep going same way until rpm stops and commences to come back down, stop and go to next. Do all four corners that way. You want rpm to rise on all four corners. If idle becomes too high, lower idle set screw and recheck with rpm meter again all four corners. Make certain carb is not loading up at first before setting air to fuel,could need float adjustment and not air to fuel. good luck.
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Old 05-05-2010, 03:33 PM
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I'll try it thanks.
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Old 05-05-2010, 03:33 PM
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Too much vacuum advance will do exactly what you describe under cruise conditions. Is it a true miss type stutter or just feel like its surgeing??. Too much timing is more of a surge feeling.
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