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73-87 Chevy _ GMC Trucks => Engine/Drivetrain => Topic started by: 1981 ss chevy on August 22, 2010, 04:00:46 pm

Title: Black smoke from exhaust
Post by: 1981 ss chevy on August 22, 2010, 04:00:46 pm
I read through the archives but couldnt really find an answer i needed.  So here is my problem, I have an 81 c10 350/th350 350 has edelbrock intake 1406 edelbrock carb headers.  It runs great starts however when going down the road and I floor it it runs awesome at about 6000 rpm and sounds great but the passenger exhaust tip has black some coming out of it and I have true duals no x or h pipe.  Supposedly that means running rich or unburned fuel.  Now how do I go about fixing this? new plugs? tune carb? adust timing?
Title: Re: Black smoke from exhaust
Post by: Irish_Alley on August 22, 2010, 04:48:40 pm
Well since both sides share the fuel I don't its cause the Carb is too rich I would start with a tune up plugs wires and se what you come up with then
Title: Re: Black smoke from exhaust
Post by: 1981 ss chevy on August 22, 2010, 05:05:18 pm
ok im going with plugs because i got new summit plug wires when i swapped intakes only about 2k miles ago
Title: Re: Black smoke from exhaust
Post by: fitz on August 22, 2010, 06:07:37 pm
it runs awesome at about 6000 rpm

What are you running for a cam that needs to rev to 6K to make power?
Title: Re: Black smoke from exhaust
Post by: bake74 on August 22, 2010, 06:33:28 pm
  Since you have a true dual exhaust, and it is only happening on the passenger side, you need to concentrate on the passenger head. ( anything that shares for both side would not be the problem, ie the carb,)  I would start with the plugs and see if any on that side are burnt, fouled out, or worn off prematurely.  Then I would move on to a compression check on that head on all cylinders and see if any or weak or maybe 2 or weak together (meaning possible blown head gasket), good luck and keep us posted on what you find.   Tom
Title: Re: Black smoke from exhaust
Post by: 1981 ss chevy on August 22, 2010, 10:46:40 pm
to my knowledge the cam is stock but idk the motor was rebuilt once before i got it.  and it makes power lower then that, thats just what it shoots up to when i hammer it and it shifts down
Title: Re: Black smoke from exhaust
Post by: 1981 ss chevy on August 22, 2010, 10:48:41 pm
bake74, if i had a bad head gasket it would be burning water then and the smoke would be white right?
Title: Re: Black smoke from exhaust
Post by: bake74 on August 22, 2010, 11:21:33 pm
   More than likely white smoke, but I have had some weird issues arise with blown head gaskets.  A compression check can do more than tell you if you got a blown head gasket, it can tell you if you possible have problems with your valves, rings, or a combination of things.  I was suggesting you just check a few things and get a good idea of what you have and don't have, then it will be a lot easier to diagnose and somebody here probably already went through it and could save you some time and money.    Tom
Title: Re: Black smoke from exhaust
Post by: 1981 ss chevy on August 25, 2010, 07:27:48 pm
Ive never checked the compression how do you got about doing this?
Title: Re: Black smoke from exhaust
Post by: Lt.Del on August 25, 2010, 09:05:14 pm
get a compression guage from any auto parts store. Warm up the engine. Take the hot wire from the distributor so the engine won't fire.
remove a spark plug.  Put the guage in and hold it tight in there.  Have some turn the engine over a few times times--it will record the highest compression reading.  After noting the pressure, reset it and try another cylinder.  The trick is to get a reading on all cylinders and see if any one or two are way off.  

At least that is how i did it years ago.   They make them with a screw in hose--that screws into the spark plug hole now--i didn't have that luxury back then.  So, only one person can do a test now. Put oil on the threaded part that screws into the spark plug hole.

http://www.youtube.com/watch?v=XcmIPm8M3Xw&feature=related

Title: Re: Black smoke from exhaust
Post by: beastie_3 on August 26, 2010, 12:06:14 am
You should be able to rent them at the local parts store, O'rileys is free.
Title: Re: Black smoke from exhaust
Post by: 1981 ss chevy on September 12, 2010, 11:56:52 am
put in some new plugs now its good to go
Title: Re: Black smoke from exhaust
Post by: beastie_3 on September 12, 2010, 02:48:05 pm
did you ever check compression?
Title: Re: Black smoke from exhaust
Post by: 1981 ss chevy on September 12, 2010, 09:13:05 pm
was going to but oreillys in town didnt have one you could rent, you had to buy one so i just said screw that i tried new plugs and it worked, if it hadnt i would have had to buy a compression tester
Title: Re: Black smoke from exhaust
Post by: DnStClr on September 13, 2010, 03:59:36 pm
Hope you found the problem but you may find it reoccuring if that head is bad. A compression tester won't set ya back that much cash and will come in handy. It's a great troubleshooting tool.
Title: Re: Black smoke from exhaust
Post by: 1981 ss chevy on September 14, 2010, 09:09:26 pm
i probably should invest, once i get my next paycheck