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Q: When giving the car gas it feels like its sputtering, or misfireing kind of jerk on 1990 Buick Riviera

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1973 buick riviera, 455 big block, just replaced spark plugs and wires. Everytime i press the gas it is doin it, it idles perfectly fine but in referse or drive it sputters
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Also possible retarded ignition timing, distributor vacuum advance inop. or vacuum improperly hooked up, carb. accelerator pump problem or egr valve operation.
I'm confused, is it a 1990 or a 1973?
If it is a 1973, have you checked the dwell and timing? For you guys that don't know what dwell is on a 1973 Riviera, it means taking a dwell meter or a good DVOM and look at the percentage of time the POINTS are open. Yes I said points. Here's some more info.

At ordinary engine operating speeds, the points open and close a couple of hundred times per second, the exact number depending on the number of cylinders and the engine RPM. The points need to be closed for a appreciable time in order to build up the maximum magnetic flux in the ignition coil core.

The period of points closure is specified by the ignition system designer and is typically expressed as degrees of distributor rotation. In a four cylinder engine, the angle between each ignition cam lobe is 90° and the period of points closure or "DWELL" is usually a bit over 45° of distributor rotation. In a six cylinder engine, the lobes are 60° apart and the dwell time is 30° to 35°.

The dwell is adjusted by setting the points gap to a specified distance at maximum opening. A narrower gap gives more dwell and a wider gap gives less. Taking it to extremes, excessive dwell means that the points close too soon after opening, cutting off the magnetic field collapse before it delivers all its energy. Too little dwell gives the magnetic flux insufficient time to build up to the maximum.

Both conditions give a weak spark which gets even weaker as the engine RPM rises and produces misfiring at normal operating speeds. The dwell, as well as spark plug gap, do have an effect on ignition timing. The later the points open, the later the spark comes and retards the timing. The earlier the points open the sooner the spark comes and advances the timing. That is why timing is the last thing to be set in a tune-up.

The way I set the dwell is this; remove the distributor cap and rotor, ground the coil wire and remove all the spark plugs from the engine. Set up your dwell meter and hook up a remote starter. Turn the key ON and crank the engine. Adjust the points to the desired setting and tighten the points. Crank it again to be sure the dwell angle is still correct.

With GM points it's a lot easier. They have an adjuster built into the points and a little door in the distributor cap. This allows you to adjust the points while the engine is actually running.

This is an education for those younger techs.
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