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| back firing through intake https://slantsix.org/forum/viewtopic.php?t=27388 |
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| Author: | kit [ Sat Feb 23, 2008 9:53 pm ] |
| Post subject: | back firing through intake |
I have a 1979 dodge van with a single barrel carb that has been back firing through the intake for about a year now. Its started off only under a load, going up hill and stuff and slowly has gotten much worse. I had to replace the carb, the old one had badly stripped holes, and I figured that may solve the problem, but it still does it really bad. I bring it up to 2000 rpms with no load on it and it just pops and cracks. I have also checked the timing and its good. |
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| Author: | LUCKY13 [ Sun Feb 24, 2008 4:01 am ] |
| Post subject: | |
I would run a compression test next. also at the same time while your in there pull the valve cover and check the rocker arms, pushrods,valve springs, and Valve Lash ajustment. Hopefully you will find one out of ajustment ( maybe even to tight). Pay real close attention to the intake rocker arms and there ajustment. The truth is I expect you might have a bad intake valve, or a exhaust cam lobe wiped out. The compression test and inspection of the valve train will help answer these questions. If you dont seem to find any problems rotate the engine and watch the rocker arms and see if any of them are not moving much. You will want to unhook the coil wire so the engine does not start up on you when you are turning it over to inspect for rocker arm movement. May get a friend to help with this while one looks and the other cranks the engine over. Jess |
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| Author: | 6shotvanner [ Tue Feb 26, 2008 6:29 am ] |
| Post subject: | |
Kit,figured I'd post something and get this back up to the top of the rotation,maybe one of our experts will see it.Besides us token van folks need to help each other out.Have you tried things like new plug wires,cap and rotor? You can get a cross fire that sort of mimicks a back fire.Did the timing dance around any when you had the light on it? Good luck 
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| Author: | SlantSixDan [ Tue Feb 26, 2008 12:09 pm ] |
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How many miles are on this engine? What kind of exhaust system is fitted? I'm thinking along lines of improper cam timing and excessive exhaust restriction. |
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| Author: | slantzilla [ Tue Feb 26, 2008 12:58 pm ] |
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Banging through the carb that has lasted that long and gotten worse is usually a symptom of a burnt intake valve. Could also be a bad cap/rotor/wires. If you are lucky a valve adjustment will cure it, but after this long you'd be real lucky. |
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| Author: | LUCKY13 [ Tue Feb 26, 2008 1:32 pm ] |
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Good piont with the exhaust, a restricted exhaust could cause all his problems plus give the rich carbon smoke at startup from the excess fuel left behind from the restriction. Infact that is about what that spark plug looks like instead of excess oil from the rings not being broke in. A vaccum test could anwser that real quick. Jess |
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