Idling Rough, Stalling, and Knocking OH MY!!!

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Old Sep 21, 2019 | 09:12 PM
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Idling Rough, Stalling, and Knocking OH MY!!!

Hey all, im back and with plenty of things that'll pick your brains.

First off, lets start off with the car, its a 1978 Oldsmobile Custom Cruiser with its original 350 V8. The transmission is not original, but we'll save that for another thread. The car has either 150k or 50k miles, but has sat for 5 or 6 years, the title doesnt say that it had exceeded its mechanical limits and its red leather interior is immaculate.

The car has had a really rough intermittent idling problem that makes it unable to drive without it potentially dying just cruising down the road and will not stay running while idling unless i hold the choke plate slightly more closed than it is. Durring cold start up it runs fine but continually increases fairly quickly and once i tap the gas unless i can jump out amd pull the choke plate back a bit it will die. Ive searched for vacuum leaks but cant seem to find any. Durring this trough idle its bugun to knock intermittently sounding like a pinball shooting around in the front driver side. When given gas it would rev fine and accelerated good. But since i started messing with it tonight to correct the issue i havent driven it as it just gets worse as it warms up.

I had to stick a piece of cardboard next to the chock plate arm to hold it between a quarter or an eighth more closed to get it home. By the end of tonight i couldnt even get it to start even with spraying ether in the carb or depressing the pedal all the way.

Where shall i begin?
Old Sep 21, 2019 | 11:36 PM
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You didn't say what you've done to it so far. I'd never try to start a car sitting that long without flushing the fuel system and rebuilding the carb.
Old Sep 22, 2019 | 05:29 PM
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Well, i changed the sending unit and flushed the tank for the most part then changed the fuel filter as well as all fluids. It would start in cold loop last night but by operating temp it would die unless i held the choke partially closed then would speed up rms and smooth out. Without messing with the choke it would idle very hard and knock in such a way that it sounded like a pinball shooting around in the front passenger side. Increasing with rpm but not rhythmic at all. Again, once i held the choke parially shut it would idle fantastic. I tried adjusting the choke while it was hot to give it some more tention and ended up not getting it to start at all last night or this morning up until now even. It turns over fast and wants to start but doesnt
Old Sep 22, 2019 | 05:30 PM
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Carb also shoots 2 steady streams when accelerator pump is depressed, i suspected vacuum leak but cant find one anywhere
Old Sep 22, 2019 | 05:41 PM
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Basically, i think i need the master of classicolds Mr Joe P to give me a lesson or two. Hes a God here IMO
Old Sep 22, 2019 | 06:02 PM
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Originally Posted by Goodoldsreliable
its bugun to knock intermittently sounding like a pinball shooting around in the front driver side.
Originally Posted by Goodoldsreliable
knock in such a way that it sounded like a pinball shooting around in the front passenger side.
So you have the sound of pinballs shooting around both the right and left sides.
Old Sep 22, 2019 | 06:37 PM
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Originally Posted by Fun71
So you have the sound of pinballs shooting around both the right and left sides.
No, just the front left corner driver side. Does not sound good when its happening

I misspoke in the second quote
Old Sep 22, 2019 | 06:55 PM
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All original vacuum routing is still where it should be as well.only adaption i see is a hot wire spiced to the distributor
Old Sep 23, 2019 | 07:26 PM
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Engine is now running and idling fine, but the knock persists. I dont like having the engine running it sounds so bad. Anyone able to help me shed some light on what it might be?

I'm young and persistent. I will get to the bottom of this with all of your guys help. Youve never steered me wrong and have been here with me through many troubles
Old Sep 23, 2019 | 07:47 PM
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Is it the valve train or lower in the block?
Old Sep 23, 2019 | 07:58 PM
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I had the valve covers off tonight and the middle two rods were surrounded with gunk burnt gunk that extended to the other neighboring two. It sounds lower... It sounds very bad..

It didnt do this when i first bought it a month ago when i changed the oil and started it up just to see if itd start and it sounded pretty good. I only ran it for a minute or two though.

it started once i tried fine tuning it after getting it home because it started to idle funny. And once it warmed up it started to onock and now does cold as well
Old Sep 23, 2019 | 08:20 PM
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Pull the spark plugs 1 by 1 and run the engine each time and see it stops and you can narrow it down to a cylinder.
Old Sep 23, 2019 | 08:53 PM
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It sounds like it is running super lean, they idle very lean stock. What is the timing set at?
Old Sep 23, 2019 | 09:58 PM
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Irs 1am here so ill get back with both of those results tomorrow morning first thing. Please throw anything else at me you think might be the culprit as well and ill look at everything you guys have suggested. New plugs and wires today as well
Old Sep 24, 2019 | 12:41 PM
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Well, im sad to say it but it has been confirmed that the head is blown..

I suppose i have no choice but to pull the top end and rebuild.

Guys, i might need some help with this one... ill start a new thread and hope you all can give me som suggestions which parts to order from where as id like to do this right.
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