1988 Chevy Silverado Missing under power

1988 CHEVROLET SILVERADO
100,000 MILES • V8 • 2WD • AUTOMATIC
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BWMILLER
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  • 1 POST
I have 1988 chevy silverado 305 half ton 2 wheel drive automatic. It idles fine but misses badly under power. I have replaced the egr valve, egr pressure switch, fuel injectors, the diaphram in the carb, distribitor cap and rotor button, checked timing, it is correct so timing chain is ok. The coil is functioning fine and i have spark to all cylinders
Sep 30, 2009 at 2:14 AM
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DANAUTHIER
  • ✓Experienced Mechanic
  • 156 POSTS
Check the main shaft in the distributor, they are known for developing hair line cracks along the length of the shaft. This causes the symptoms you describe. At idle there is little torque on the shaft but under accelleration the cracks allow the shaft to twist, which retards the timing and causes the miss.
To check this you need to remove the distributor assembly and disassemble it. The cracks may be difficult to see.
Just an idea, let me know what you find.
Dan
Sep 30, 2009 at 2:33 AM
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