Mechanics

ACCELERATION HESITATION/STALL

1978 International Scout

Engine Performance problem
1978 International Scout V8 Four Wheel Drive Automatic 73000 miles

Engine idles very well, on sudden acceleration, coughs, hesitates, and often dies. I have checked for vacuum leaks, replaced carburator with working used one,new fuel pump, changed fuel filter(fuel flows easily) new ignition coil,wires, distributor cap,points, plugs and condenser. I have set the timing and checked for spark advance with and without vacuum line connected. When slowly increasing RPM, it develops a cackle as if a sticking valve, but will continue to run. often dies when shifting from park or neutral to drive. This vehicle is used for off road only, and all vacuum ports are plugged out of carburator except the one going to the vacuum advance selenoid. I would like your opinion, please. Don


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Donald Owens
March 11, 2010.




Checked the routing of the plug wires? Nothin crossed? Check compression wet and dry. Test then add a few drops of oil and test again, all cylinders! Timing chain have any slack? Distributor have any sideplay? Dwell remain constant up to 2000 rpm? Last, does it have a heat riser on the manifold between the exhaust manifold and pipe? Could be stuck. Egr closed fully? Or was it eliminated? How d you know the used carb is good? Mixture been set to this engine?

Merlin2021
Mar 11, 2010.
You never mentioned what type of carb, manifold you have. Stock Holley or Quadrajet? Or aftermarket Holley, Edelbrock? I had the same type of problems when using an Edelbrock (on a spreadbore manifold) until I bought the needle set and changed out the needles to one size up.
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Tiny
Jellyco
Mar 12, 2010.

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