Going down the road steady-state…45…55 mph can feel engine is not smooth…it “bucks,” it’s a 62 318 poly…my 350 in my 58 DeSoto did this and I put in new condenser…fixed it. Tried it on this 318…didn’t work. Have also changed points and coil too. Still does it. Engine is not a smooth idler either. Did compression test. Range from 125-140 all 8 cylinders. Think it could need a valve adjustment? Thanks…
What makes an engine “buck?”
- Thread starter furyfever
- Start date
65sporty
Old Man with a Hat
What are the plugs and wire like? If it's more like a sharp jerk, it's probably an ignition miss caused by a spark plug or wire
Compression numbers look good. "Bucks" are related to tuning. First check for vac leaks, including the vac advance diaphram. Might be plug wires, with one or two that are "leaking" voltage? New ign condensers can be bad, too. Find an old one.
Sounds like a lean surge. What shape is the carb in?
Cartel
Member
usually something in the ignition. points, loose nuts on the coil wire, loose connection on the ballast resistor, maybe the ballast resistor is going. loose plug on the ignition switch.
crusty fuse...or maybe floats are too high? if the idle mixture dont do much the butterflies might be too far open. super sloppy timing chain might cause it too
crusty fuse...or maybe floats are too high? if the idle mixture dont do much the butterflies might be too far open. super sloppy timing chain might cause it too
Blusmbl
Member
Agree completely, lean usually will be a surge feel. If it's actually bucking that's more likely to be an ignition related misfire.
If you find the idle adjustment screws aren't doing anything you either have a vacuum leak or you have the throttle blades open too far.
You should be able to kill the engine with those adjustment screws
70bigblockdodge
Old Man with a Hat
Wire/tie the choke 1/2 shut, drive car. If surge/buck is gone/better it's your carburetor. Otherwise it is ignition, any new condensers can be suspect of being bad ootb or soon after
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