Question about Chevrolet Silverado 1500

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1996 5.7 running to rich after replacing the heads, distriputer,plugs wires valvegaskets but now mprs about 8 miles and blacksmoke pretty bad increasing to around 3000rpms and missing often at a idle

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  • bugg1rl579 Jul 21, 2009

    I had a buddy Nicks Automotive do the work so i really dont know about the gaskets beside they were all new,the heads simply went to napa, the new cap plugs and wires were new also but basic, i replaced the wires after he put it back together because they were on the manifold so it could maby a issue with timing also. I did use seafoam twice, but never gained fuel milage im to the point that ive replaced every major componet on the truck but the small things are driving me crazy and ready to sell without getting near the money iv got in it.

  • bugg1rl579 Jul 24, 2009

    i took the truck back to nicks today and scanned it, were starting with the 02 sensor on the left bank. as far as the timing ill ask him tomorrow but im sure its dialed in. the scanner pulled a number of codes that hopfully are due cause o the senser.

  • bugg1rl579 Jul 24, 2009

    What would you estamate its value, 1996 z71 160,000m leather power everything, also providing resepes for heads,gaskets,tranny and differant upgrades?

  • bugg1rl579 Jul 24, 2009

    It was help in narrowing detaled info but still would like to chat



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I have to ask you few tough questions. You may reply via email later.

Did you send the heads out to CNC milling and re-seat all the valves?

Did you use new head bolts?

Did you use Indian Head (picture on the bottle) head gasket sealer?

Did you torque the bolts in the correct pattern and pressure?


The first thing to check is the intake manifold gasket leak.
Used a little Berman clear to spot check for leak around the manifold leak(s)


Monitor the coolant and oil level.


Black smoke is un-burn fuel.

Did you inspect the injectors?

Did you change the Fuel Rail O-Rings.

A dripping or poor spray pattern can lead to all the problems you posted.


I would use a bottle of Lucas or Seafoam fuel system cleaner and hope it's just few poor performing injectors.

Please email me you answers and I will have a better picture on hold to trouble shoot you Chevy.

Good Luck

Posted on Jul 20, 2009

  • Vincent_G
    Vincent_G Jul 21, 2009

    When you remove the head,did you check the timing chain?

    In general the timing chain will last much longer the timing belt but I would change it at 180,000 or less.

    I hope you can get hold of a timing light and set the correct timing.

    The timing info is on the sticker under the hood.

    3,4,5 before TDC.

    You have to factor in the give on the chain too.

    Do ran you truck too much because TOO FAR ADVANCE can burn the valve and you will be back to square one.

    Please keep me up to date.



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