Oh the horror, what happened to my 340...

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Have you got another known good carburetor you can try? You don't even have to hook up the kickdown. Just one to stick on it and see. That would be my first choice, because it's EASY to do and right there on top.
 
RustyRatRod said:
Have you got another known good carburetor you can try? You don't even have to hook up the kickdown. Just one to stick on it and see. That would be my first choice, because it's EASY to do and right there on top.
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Oops wrong thread?
 
toolmanmike said:
Oops wrong thread?
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Nope. If the carburetor is making the engine run that ROUGH, whatever the knocking sound is could be just something rattling around that normally doesn't when it runs smooth.
 
I agree with flex plate or trans related. Mine sounded like that when the transmission puked. When I pulled the trans pan, the strut bar was laying in the bottom of it.
 
I just don't agree with a mechanical failure on this one. How will loose converter bolts make an engine run rough? Ain't happenin. However, on the flip side, a carburetor that's flooding can make an engine run rough, sound like it had s pro stock cam AND make something somewhere rattle that normally doesn't when it runs smooth.
 
Well, it sounds like it was purring like a kitten and was shut off. A couple weeks later it was started and it was making the noise. Unless it was stolen by a teenage son and it went for a joy ride and was blown up and then parked back in the garage, something happened when the key was turned. It sounds like something broke.
 
Can cut your oil filter open and see if any steel is showing up in there. Take a magnet to the paper element too.
 
cudamark said:
Just where does he say that?
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Ok it wasn't the OP. Look at post #6. Also LOOK at the engine in the first video compared to the second. A blind man could see the difference.
 
It's nearly impossible to diagnose based on a video. The video, to me, sounds like a typical V8 with a bit of cam and leaky headers. But sound reproduction, especially in the digital age....you know you're not listening to the real thing. For all I know, it could be the new Lady Gaga song, only smarter.
 
Sounds like a broken rocker to me, maybe pushrod went straight through it. Had it happen on one I had just built only 2 hours in, replaced it and all is great!
 
AlV said:
Went to fire up the Dart today and was greeted with the stomach turning sound of cans banging around in the engine. It's out of the blue.


It normally sounds like this.


Not sure what happened yet.

AlV
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Remove the plugs and read them for signs of damage or dare I say coolant.
While the plugs are out remove the valve covers and kill the ignition, crank the engine over and visually check the top end for proper operation.
Cut the oil filter open and check for metal.
 
Well, after a week I finally had some time to work on the Dart and have some results. Let me start by saying thank you to everyone for offering feedback and sharing your thoughts. As discussed, I started with the easy first.

  • I disconnected the ignition coil and turned the car over which made it easier to hear the noise without the rumble of the engine. Yes, clanging was present.
  • Then I removed the air cleaner to inspect the carb and see if it was dumping fuel, but it was not so, I covered it up for now.
  • Next, I installed a remote starter then removed the valve covers. Nothing glaring stood out in fact everything looked pretty good. I cranked the engine and heard the noise again but with the covers off I could see the valves were operating as expected but it became apparent that the noise was coming from the bottom and not the top.
  • At this point I was certain the noise was coming from the transmission and was hoping it was just the converter bolts so I disconnected the battery, removed the engine supports and starter to get the inspection cover off. With the cover of it was instantly clear the bolts had come loose so I removed them all and pushed the converter in to make room to inspect the crank bolts and flex plate. Both were fine meaning not loose or cracked so I snugged up the converter bolts, installed the starter and cranked it again. No Noise! The clanging was gone. YES!! I am going to get a new set of converter bolts to replace these dinged up ones.
  • At this point I was feeling good and decided to play a little more mostly because I had borrowed a friends Eddie 650 Carb. I removed my Holley Street Demon 670 and installed the Edelbrock 650, reconnected the ignition coil and battery then fired it up and I have to say that it seemed to run better and smoother with the Eddie?!.
I plan on leaving the Edelbrock carb on for now so I can collect some data because I think I’m going to need to change the jet sizing on the Holley. To help I have picked up an AFR meter and a bung to weld into the exhausts.

Feeling like I "Dodged" a bullet :thankyou:

AlV
 
AlV said:
Well, after a week I finally had some time to work on the Dart and have some results. Let me start by saying thank you to everyone for offering feedback and sharing your thoughts. As discussed, I started with the easy first.

  • I disconnected the ignition coil and turned the car over which made it easier to hear the noise without the rumble of the engine. Yes, clanging was present.
  • Then I removed the air cleaner to inspect the carb and see if it was dumping fuel, but it was not so, I covered it up for now.
  • Next, I installed a remote starter then removed the valve covers. Nothing glaring stood out in fact everything looked pretty good. I cranked the engine and heard the noise again but with the covers off I could see the valves were operating as expected but it became apparent that the noise was coming from the bottom and not the top.
  • At this point I was certain the noise was coming from the transmission and was hoping it was just the converter bolts so I disconnected the battery, removed the engine supports and starter to get the inspection cover off. With the cover of it was instantly clear the bolts had come loose so I removed them all and pushed the converter in to make room to inspect the crank bolts and flex plate. Both were fine meaning not loose or cracked so I snugged up the converter bolts, installed the starter and cranked it again. No Noise! The clanging was gone. YES!! I am going to get a new set of converter bolts to replace these dinged up ones.
  • At this point I was feeling good and decided to play a little more mostly because I had borrowed a friends Eddie 650 Carb. I removed my Holley Street Demon 670 and installed the Edelbrock 650, reconnected the ignition coil and battery then fired it up and I have to say that it seemed to run better and smoother with the Eddie?!.
I plan on leaving the Edelbrock carb on for now so I can collect some data because I think I’m going to need to change the jet sizing on the Holley. To help I have picked up an AFR meter and a bung to weld into the exhausts.

Feeling like I "Dodged" a bullet :thankyou:

AlV
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Well that's great. I am super glad it was so simple. Did you put blue locktite on the bolts and torque them to spec?
 
RustyRatRod said:
Well that's great. I am super glad it was so simple. Did you put blue locktite on the bolts and torque them to spec?
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Glad it wasn’t anything serious.
Been following this and wanted to tell you that it’s real common to drive the car with no noises from the converter bolts and then they make noises the next time you drive.
Heat swelling makes them a little tighter and next time it’s started everything is cold and loose because the metals contracted.
Seen this more than a couple of times.
 
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