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2nd Gen ('73-'77): Misfire, rough running.

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Old 02-07-2012, 02:19 PM
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Question Misfire, rough running.

Alright, so i now have my 77 Monte running, but just barley. Fuel delivery is fine, Its my pistons, they are not correctly firing. I am burning a tiny percent of the fuel, spitting out grey smoke from the exhaust, thick enough to literally choke on, and i can feel the pistons not correctly firing and hear the engine loping when it idles, the idle will not last too long. Few mins was the best i had. Timing was reset, and is correct. The plugs were replaced somewhat recently, all fine. Compression is dead on +/- 5 psi from 150, which is what the factory compression was. The spark wires are a little worse for wear and the distributor is a little worn, but is receiving a full 12volt charge and is securely attached to the block. So is it the wires? Im under the impression its the ignition due to the poor percentage of fuel burn and misfiring, but anyone who has any clue on what i should be checking please correct me. I am very new to cars, this being my first project car ever. I am by no means a mechanic, and hope someone with any experience can give me advice on this. Thanks
 
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Old 02-07-2012, 08:24 PM
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Double check the wires are routed to the correct plus.if the wires are crossed it will run real rough.What carb are you running?Might need a rebuild.You might have an issue with the cam the 305's were know for wiping the lobes off back in the day not so much with the 350 but still happened.
Those are a few things that could be wrong.I'm not there to hear/see it run so this is just guessing.
 
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Old 02-07-2012, 10:25 PM
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haha i wrote a response on my droid, then forgot to submit. anyway, Ive checked the wires three times now, and checked timing twice so im pretty confident on that, but i have the original qudrajet 4BBL carb that came stock in 77 on the 350 i believe. Ive checked all the rocker arms, all have a good response when idling, none are missing a beat so that tells me my cam is fine, right? It feels like the ignition still, mabey its the whole distributor assembly? the cap has been replaced but i havent dug any deeper then the rotor.
 
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Old 02-08-2012, 06:02 PM
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Here, figured this might help, Engine isnt running right - YouTube
 
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Old 02-08-2012, 07:56 PM
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Doesn't sound right.Is it still stock or has any thing been done to it that you know of?It does have a miss to it.It's not popping like crossed plug wires would.I'm not a fan of the old quadurajunk's that came on there.There a bit of a pain if you don't know how work on them most people swith to a eddy or holley.I have a 670 holley on mine.they don't stick like the quadrajunk
 
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Old 02-08-2012, 08:04 PM
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The previous owner was not reliable of source of info, I belive its stock but im also under the impression someone has messed with it. Could that be the source of the problem? Any way to check it and get difiniative proof?
 
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Old 02-08-2012, 08:31 PM
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Want to say the cam doesn't sound stock?but it's kinda hard to tell.
If you had a dial indicator i would check to see if the intake an exhaust lift is the same for all lobes.You might be able to use a ruler to see if they lift the same.The carb might be flooding out I had that problem back when I still ran a quadrajunk.Summit has rebuild kit's for them but i've never redone one.

With out really being there to tear in to it I can't really think of any thing else to check
 
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Old 02-08-2012, 08:42 PM
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It has a replacement muffler, just incase your hearing that. Nothing special though. I could belive a replacement cam considering how old it is but also it has been in the ownership of some unreliable people, and from what I can tell when it was.running before I purchased it, it was not running well. Im considering removing and tearing down the engine with a complete rebuild but I really need justification for that, don't want to sink that money in and find out it was a problem that could be solved wheels on the ground. What do you think about that? Im.confident enough to do the rebuild but should I do more diagnostic work before it comes to that? Thanks for the help so far also, very appreciated
 
  #9  
Old 02-08-2012, 09:03 PM
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how did you check the timing?
 
  #10  
Old 02-08-2012, 09:10 PM
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Hand turned the crank with the distributor cap removed, checked that the rotor lined up with the first piston compression stroke and first spark wire
 


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