86 Silverado engine problems

Tiny
VEGASMSTRJ
  • MEMBER
  • 1986 CHEVROLET TRUCK
Hi everyone.I have an 86 Chevy Silverado with a mostly stock 305 and 700r4 tranny. The motor has like 270,000 miles on it! About 2 months ago I had the timing chain, gasket, valve cover gaskets, and intake gasket replaced. I put a holley carb on it and it was tuned also. Recently I flew home and my truck sat for 10 days. When I returned, it started instantly and had no problems, but as I was driving home (90 miles) I filled up with regular fuel even though I usually run premium(damn gas prices). The truck was a little sluggish but I thought it was normal because of the fuel. I stopped at a stop street and it stalled. When I try to accelerate, its really sluggish and makes popping sounds. I checked under the hood and played with it a little bit and saw black smoke from the valve covers when I rev it. It also looks like some oil sitting on the intake towards the back, maybe from bad intake gaskets? I did make it back safely. The next day I filled it up with premium and got some fuel system cleaners and sprayed the carb with carb cleaner. Still no help! I probably should add that I pulled the dual exhaust pipes apart so I could have really loud wide open headers because I live on a military base and they dont care. But I'm not sure if doing that for a while will mess with the engine or not. I'm hoping its not a serious engine problem, but I guess that's to be expected with an old vehicle. Any thoughts or suggestions would be awesome! Thanks!
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Monday, January 2nd, 2006 AT 6:25 PM

8 Replies

Tiny
VEGASMSTRJ
  • MEMBER
Nope, it originally had a Rochester 4bbl carb.
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Friday, January 6th, 2006 AT 5:51 PM
Tiny
VEGASMSTRJ
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I was told to change the fuel filter, so I did. No change. :( Also I checked the oil and it looked black like usual and smelled normal.
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Monday, January 9th, 2006 AT 5:50 PM
Tiny
PALCO
  • MEMBER
The black smoke from the valve cover area on accel. Running with open headers. Poping, slugish. I'd say you have a worped and/or burnt exhaust valve or two. When you run open header and the turn the engine off. The thin walls of the header(as aposed to thicker casting of a normal manifold) cools realy quickly and as it cool draws up cold air to the still hot valves. Still nesseled in a warm water thick casting. And any open valve can worp. And a cyl. In the sweet spot can let cool air into the comustion chamber and get an intake valve also. Thats why when you run a full exhaust sys. You get condensation in the muffler. Witch comes out as steam while warmig up the car. Good luck
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Monday, January 9th, 2006 AT 8:10 PM
Tiny
VEGASMSTRJ
  • MEMBER
Hmm. That sucks. The truck is still running and the problems have'nt gotten better or worse. How long can I drive it before it blows up and anyone have an idea how much it would cost to repair?

Thanks!
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Friday, January 13th, 2006 AT 9:22 AM
Tiny
ROLFESJ
  • MEMBER
Do you or a friend have the capabilities of running a compression check?

I would also check the spark plug wires to make sure some one has not crossed them for you.
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Friday, January 13th, 2006 AT 10:46 AM
Tiny
VEGASMSTRJ
  • MEMBER
I will definately look into a compression test, but im sure I have the plug wires right. Thanks for the post!
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Saturday, January 14th, 2006 AT 11:30 PM
Tiny
CHAMPION843
  • MEMBER
Check your timing, if your time is right then try your fuel to air ratio. Sometimes you have to readjust after making a switch of gasoline types if you go from high quality to a lower one.
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Sunday, January 15th, 2006 AT 10:31 AM
Tiny
VEGASMSTRJ
  • MEMBER
Thanks! That would make sense because I have alot of white smoke out the back. Tells me its not burning right. I'll check that out.
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Wednesday, January 18th, 2006 AT 9:05 AM

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