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Re: Noticeable Drivetrain Shake at Idle
[Re: MuuMuu101]
#1542136
12/01/13 11:52 AM
12/01/13 11:52 AM
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Joined: Nov 2003
Posts: 36,040
Lincoln Nebraska
RapidRobert
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Circle Track
Joined: Nov 2003
Posts: 36,040
Lincoln Nebraska
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It ain't from that (low comp in 1cyl). There is something else going on that's affecting multiple cylinders. Get down there & do a quick visual to eliminate the mtr mounts. check rotor phasing, blast out the 2 carb mixture screw holes with brake kleen, check the plugs & wires. Spray for vac leaks. EDIT Is that a solid lifter 273? Not sure if the lash was way off if that would do it otherwise if so I'd think it would of showed up on the compression test. Maybe someone can chime in if that is a potential
Last edited by RapidRobert; 12/01/13 12:23 PM.
live every 24 hour block of time like it's your last day on earth
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Re: Noticeable Drivetrain Shake at Idle
[Re: elmor353]
#1542138
12/01/13 07:38 PM
12/01/13 07:38 PM
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Joined: Dec 2010
Posts: 12,375
SoCal
MuuMuu101
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I got lucky at Woodward!
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Quote:
I had the same problem with the 440 in my truck. Didn't seem to notice when driving it, but at an idle, it shook pretty bad. Had a burnt exhaust valve and no compression in one cylinder. What were the rest of your cylinders running for compression? Normally you don't want to run more than 10 percent difference.
I believe he said the others were running somewhere around 120-130 psi. I'm not too sure. Honestly, I don't know too much about engines or how to troubleshoot them, but I'll be done with my next school quarter in 2 weeks and may have some time to fiddle around with it during my Christmas break.
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Re: Noticeable Drivetrain Shake at Idle
[Re: JohnRR]
#1542141
12/01/13 09:32 PM
12/01/13 09:32 PM
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Joined: Dec 2010
Posts: 12,375
SoCal
MuuMuu101
OP
I got lucky at Woodward!
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I got lucky at Woodward!
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Quote:
What ignition system on the engine? This is not a drivetrain vibration if it is happening when stopped and at idle, this is an engine vibration.
It's electronic. Someone swapped out the standard points system.
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Re: Noticeable Drivetrain Shake at Idle
[Re: 340SHORTY]
#1542142
12/01/13 09:33 PM
12/01/13 09:33 PM
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Joined: Dec 2010
Posts: 12,375
SoCal
MuuMuu101
OP
I got lucky at Woodward!
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OP
I got lucky at Woodward!
Joined: Dec 2010
Posts: 12,375
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Quote:
maybe you have lumps in your gas.. 
What do you mean by this? I do fill it up with 91 octane (highest I can get over here).
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Re: Noticeable Drivetrain Shake at Idle
[Re: MuuMuu101]
#1542143
12/01/13 10:07 PM
12/01/13 10:07 PM
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Joined: Nov 2003
Posts: 36,040
Lincoln Nebraska
RapidRobert
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Circle Track
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Lincoln Nebraska
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I'd start on a few things & see if I could pin it to either fuel (carb/vac leak) or ign (plugs/wires/reluctor gap/rotor phasing)
live every 24 hour block of time like it's your last day on earth
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Re: Noticeable Drivetrain Shake at Idle
[Re: MuuMuu101]
#1542145
12/02/13 02:34 AM
12/02/13 02:34 AM
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Joined: Jan 2003
Posts: 74,947
U.S.S.A.
JohnRR
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Quote:
Quote:
maybe you have lumps in your gas..
What do you mean by this? I do fill it up with 91 octane (highest I can get over here).
Why are you wasting money running 91 in that engine ?
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Re: Noticeable Drivetrain Shake at Idle
[Re: JohnRR]
#1542146
12/02/13 02:52 AM
12/02/13 02:52 AM
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Joined: Dec 2010
Posts: 12,375
SoCal
MuuMuu101
OP
I got lucky at Woodward!
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OP
I got lucky at Woodward!
Joined: Dec 2010
Posts: 12,375
SoCal
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Quote:
Quote:
Quote:
maybe you have lumps in your gas..
What do you mean by this? I do fill it up with 91 octane (highest I can get over here).
Why are you wasting money running 91 in that engine ?
I wasn't sure what the recommended octane was. Most people I heard run 91. I just didn't want to develop an engine knock. What do you recommend?
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Re: Noticeable Drivetrain Shake at Idle
[Re: Dcuda69]
#1542149
12/03/13 12:02 PM
12/03/13 12:02 PM
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Joined: Jun 2006
Posts: 5,159
CT
GTX MATT
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I worked on a buddies 383 last year that had a dead cylinder from a burnt valve, it idled rougher than it should have but it didn't shake violently.
Is it worse in gear, even if you bring the revs up to the same as idle in park? Sounds like a busted motor or tranny mount to me.
Now I need to pin those needles, got to feel that heat
Hear my motor screamin while I'm tearin up the street
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Re: Noticeable Drivetrain Shake at Idle
[Re: JohnRR]
#1542150
12/03/13 01:53 PM
12/03/13 01:53 PM
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Joined: Dec 2010
Posts: 12,375
SoCal
MuuMuu101
OP
I got lucky at Woodward!
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OP
I got lucky at Woodward!
Joined: Dec 2010
Posts: 12,375
SoCal
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Quote:
What's the rated compression ratio ?
Edit ... mymopar.com says rated at 8.8 so it's closer to 8.0 , you should be able to run it on 87 ...
Thanks! 
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Re: Noticeable Drivetrain Shake at Idle
[Re: GTX MATT]
#1542151
12/03/13 01:55 PM
12/03/13 01:55 PM
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Joined: Dec 2010
Posts: 12,375
SoCal
MuuMuu101
OP
I got lucky at Woodward!
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OP
I got lucky at Woodward!
Joined: Dec 2010
Posts: 12,375
SoCal
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Quote:
I worked on a buddies 383 last year that had a dead cylinder from a burnt valve, it idled rougher than it should have but it didn't shake violently.
Is it worse in gear, even if you bring the revs up to the same as idle in park? Sounds like a busted motor or tranny mount to me.
It's no better or worse whether it's sitting in Park in the garage or in Drive at a red light. I'm not sure if my center console is bolted down completely, but once it starts going, you can hear and see it rattle and vibrate. It also doesn't seem to happen all the time while driving (either that or I'm not noticing it).
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Re: Noticeable Drivetrain Shake at Idle
[Re: dogdays]
#1542154
12/04/13 04:22 AM
12/04/13 04:22 AM
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Joined: Dec 2010
Posts: 12,375
SoCal
MuuMuu101
OP
I got lucky at Woodward!
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OP
I got lucky at Woodward!
Joined: Dec 2010
Posts: 12,375
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Quote:
The answer is simple, you have a bad cylinder. Your mechanic told you. One man's "rock or shake" is another man's vibration.
If you remember which hole was bad, pull the spark plug wire on it and see if it makes any difference in the engine's behavior. I bet it gets slightly worse, but doesn't change a lot.
Whatever you do, don't go making a lot of changes all at once. This is a simple problem with an expensive solution. You probably need a different engine or at least a valve job on your existing heads.
If it is a valve, you can sometimes tell by pulling the coil wire and turning the engine. Listen for a hiss every other revolution. If it comes through the carb it's an intake valve. But dollars to doughnuts it's an exhaust valve and the hiss will be heard at the exhaust.
If this is the case, I'd suggest looking for a mid-80s Fifth Avenue for heads or complete 318.
Also, unless your 273 came with a factory four-barrel carb there's no reason to put in 91 octane fuel.
Keep us posted. There's more collective brainpower on this board than in most garages.
R.
As far as I can tell it's a stock 273 with a 2-barrel (most likely original). I did check the casting on the block shortly after I got it and confirmed it was a 273. How much can a valve-job run up to? If it's more expensive it may not be worth it since 318's and 360's are available. I've got an 8 3/4 in my garage I could swap instead of the 7 1/4 just in case I want to go to more cubes.
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Re: Noticeable Drivetrain Shake at Idle
[Re: MuuMuu101]
#1542155
12/04/13 12:03 PM
12/04/13 12:03 PM
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Joined: Nov 2003
Posts: 36,040
Lincoln Nebraska
RapidRobert
Circle Track
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Circle Track
Joined: Nov 2003
Posts: 36,040
Lincoln Nebraska
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Stay on it & find the cause. You can do this
live every 24 hour block of time like it's your last day on earth
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Re: Noticeable Drivetrain Shake at Idle
[Re: MuuMuu101]
#1542158
12/04/13 12:35 PM
12/04/13 12:35 PM
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Joined: Jun 2006
Posts: 5,159
CT
GTX MATT
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master
Joined: Jun 2006
Posts: 5,159
CT
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Quote:
Quote:
The answer is simple, you have a bad cylinder. Your mechanic told you. One man's "rock or shake" is another man's vibration.
If you remember which hole was bad, pull the spark plug wire on it and see if it makes any difference in the engine's behavior. I bet it gets slightly worse, but doesn't change a lot.
Whatever you do, don't go making a lot of changes all at once. This is a simple problem with an expensive solution. You probably need a different engine or at least a valve job on your existing heads.
If it is a valve, you can sometimes tell by pulling the coil wire and turning the engine. Listen for a hiss every other revolution. If it comes through the carb it's an intake valve. But dollars to doughnuts it's an exhaust valve and the hiss will be heard at the exhaust.
If this is the case, I'd suggest looking for a mid-80s Fifth Avenue for heads or complete 318.
Also, unless your 273 came with a factory four-barrel carb there's no reason to put in 91 octane fuel.
Keep us posted. There's more collective brainpower on this board than in most garages.
R.
As far as I can tell it's a stock 273 with a 2-barrel (most likely original). I did check the casting on the block shortly after I got it and confirmed it was a 273. How much can a valve-job run up to? If it's more expensive it may not be worth it since 318's and 360's are available. I've got an 8 3/4 in my garage I could swap instead of the 7 1/4 just in case I want to go to more cubes.
It depends, usually around 250-300 in my area, plus new valves if you want them. If it were me, and this was just a 273 that I was going to cruise around, I'd take the heads off and inspect it. If it was a burned valve but was not really sunken and the seat looked okay I would probably buy a new valve and hand lap it to the seat and let it fly, this is not the best way, but will work fine.
Usually a burned valve will give you no compression in a cylinder, but you could be right at the tipping point. If its not a burned valve you've probably got a badly recessed seat, and may need to go larger with the valves or have new seats installed. Unfortunately this is a case of you don't know until you open it up.
Now I need to pin those needles, got to feel that heat
Hear my motor screamin while I'm tearin up the street
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Re: Noticeable Drivetrain Shake at Idle
[Re: OzHemi]
#1542165
12/05/13 03:11 AM
12/05/13 03:11 AM
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Joined: Dec 2010
Posts: 12,375
SoCal
MuuMuu101
OP
I got lucky at Woodward!
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OP
I got lucky at Woodward!
Joined: Dec 2010
Posts: 12,375
SoCal
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Quote:
Perfect time for an LS1 swap.. 
Only if you have a donor car and are going to help...  
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. It's all in the wheels and tires
