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09-16-2015, 12:19 PM
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#1 |
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Registered User
Join Date: Mar 2015
Location: san rafael california
Posts: 202
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Changed carb, still having issues, diagnostics?
hey all, i replaced my carburetor to try and solve backfiring through the carb and rough idle. with a new carb, and gave it a tune up , same issues keep happening. i suspect now that its something bigger and more serious going on inside the engine.
truck is burping black smoke out of the exhaust backfiring through carb idles very rough anyone have any ideas? should i just have a mechanic look at it? i get this feeling like I'm going to be looking at a rebuild or crate engine  
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09-16-2015, 12:23 PM
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#2 | ||||
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"I ain't nobody, dork."
Join Date: Sep 2007
Location: Whidbey Island, Washington
Posts: 8,971
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Re: Changed carb, still having issues, diagnostics?
99.9% of backfires through the carb are timing related.
Could be a stretched chain. Harmonic balancer outer ring has slipped on the hub. Or just plain timed way off. Do you have a timing light? Gary
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09-16-2015, 12:26 PM
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#3 |
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Registered User
Join Date: Aug 2009
Location: Bowser
Posts: 13,736
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Re: Changed carb, still having issues, diagnostics?
X2
All symptoms of a lack of timing and an idle cranked to high. What's your initial timing? |
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09-16-2015, 12:44 PM
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#4 |
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Registered User
Join Date: Jul 2014
Location: dallas texas
Posts: 1
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Re: Changed carb, still having issues, diagnostics?
Could be too tight of a vavle or broke valve spring. If running rough locate cylinder causeing miss and do compression check.
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09-16-2015, 12:52 PM
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#5 |
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Registered User
Join Date: Feb 2009
Location: Choctaw, Ok
Posts: 184
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Re: Changed carb, still having issues, diagnostics?
Is it something that happened all of a sudden or has it been gradually starting to run bad. There's a lot of different components that can cause the very issues you are experiencing. intake, timing, carb, distributor, valve train, cam...A vacuum gauge can tell you almost anything with problems you might be having. If you don't have the info on vacuum, I'll post it when I can find the link.
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choctawchevyclassics 
Last edited by choctawchevyclassics; 09-16-2015 at 12:55 PM. Reason: more info |
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09-16-2015, 01:00 PM
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#6 |
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Registered User
Join Date: Feb 2009
Location: Choctaw, Ok
Posts: 184
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Re: Changed carb, still having issues, diagnostics?
Here's a link for Vacuum Gauge info...
http://www.secondchancegarage.com/public/186.cfm Go through all of the scenarios on the page. Very interesting information.
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choctawchevyclassics
Last edited by choctawchevyclassics; 09-16-2015 at 01:04 PM. Reason: more info |
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09-16-2015, 01:34 PM
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#7 |
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Registered User
 Join Date: Jul 2015
Location: 2nd left past the stump on a dirt road.
Posts: 2,629
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Re: Changed carb, still having issues, diagnostics?
Second that on the vacuum check.
Also a vacuum gauge will not detect a leaking brake booster sometimes. Last time I went through this it was the Ignition Module in the HEI distributor and the brake booster. |
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09-16-2015, 01:51 PM
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#8 | |
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Registered User
Join Date: Feb 2009
Location: Choctaw, Ok
Posts: 184
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Re: Changed carb, still having issues, diagnostics?
Quote:
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choctawchevyclassics
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