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74 350 with Rough Idle

  #1  
Old 04-20-2010, 06:58 PM
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Default 74 350 with Rough Idle

Car idles very rough, whole car shakes.
When I give it the gas on the move it does real good, only on the idle does it run bad.
Could use some ideas on what to look for.

Thanks,

Schoon
 
  #2  
Old 04-20-2010, 07:11 PM
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Two things come to mind.
Carb, and timing. Either, or both.
Too lean, and or, over retarded.
My .02
 
  #3  
Old 04-20-2010, 07:15 PM
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BTW, she don't really start to run 'til around 1200 to 1600 rpms, right?
 
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Old 04-21-2010, 05:12 PM
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Starts to run around 1600 real good.
I checked the mixture and the timing , seems to be ok.
What I am hearing now is a nasty noise coming from the back end of the block.
Makes me think it is the distributor gear.
When I statrt the car up and let it idle no noise, only if I rev it then the noise starts and stays.
I think something is going to let go very soon.


Schoon
 
  #5  
Old 04-21-2010, 06:23 PM
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Have you got a stethoscope ( sp )?
Mighty handy tool.
You can check all kinds of things.
Your water pump, alt., P.S. pump, dist., even individual rockers. If it moves, you can listen to it do, or not do, it's thing.
I would take a real close listen to your dist.
If she's pretty noisey, I'd pull that sucker and check the gear AND the bearings/bushings.
Due to bearing wobble, the shaft may be "floating" in to line at higher rpms. Kinda like a spinning top.
Look at the inside of the dist. cap. Is there any wear showing at the plug wire posts? That's a very bad sign of a shot bearing/bushing, causing the rotor to wobble and strike the posts. That can also disrupt ingition when the rotor is not close enough to the post for the spark to jump.
Some times it do, some times it don't.
 
  #6  
Old 04-22-2010, 05:18 PM
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I agree with Dave, pull the distributor now and check it out before you do any more damage. If the gear and/or bottom bushing are worn I would change the oil and filter and use a magnetic oil plug to see if there is any garbage in the oil from the worn parts.
 
  #7  
Old 04-22-2010, 07:01 PM
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My buddy came over to see if he could identify where the noise is comming from.
He is a mechanic and works mostly on older cars.
He thinks the noise is either comming from inside the oilpan or maybe a loose valve.
This Sat He is going to get underneath and find out for sure.
I hope it's not a bearing, the engine has been rebuilt once before.

Schoon
 
  #8  
Old 04-22-2010, 07:55 PM
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"...comming from inside the oilpan or maybe a loose valve."

Might as well just say, "somewhere in the engine".
Schoon, seriously, get cha one of those stethoscopes.
You'll be very surprised by what all you can hear.
Put it on a valve cover and listen to the valve train on that bank.
What makes it so great, is you use it with the engine running, listening to your engine, "in motion".
Sure cuts down on speculation.
 
  #9  
Old 04-23-2010, 09:12 AM
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There's only one thing I can think of that matches ALL your symptoms-the aforementioned distributor gear! As you know,the distributor drives the oil pump which is in the pan.
You don't even have to pull it,pull the cap,grab the rotor and see what you can make it do. It will turn one way against the advance ,but that's only a little bit and it shouldn't go up and down at all. Good Luck!
Ron
 
  #10  
Old 05-02-2010, 12:56 PM
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Well it's looks like I lucked out.
The rattle came from two different problems.
The first problem was a bad clutch fan.
There was approx 1/4" of play when you grabbed the blades and tried to wiggle from radiator to block.
The second problem was a plug that was not firing.
This was causing the bad idle and probabbly had something to due with the rattling.
My buddy said the AC plugs I was using suck.

Schoon
 

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