Slant Six Forum :: Engine wobble- vac leak or ??

and it's somewhere around 12 degrees after TDC, but it starts chugging and quickly dies if I start adjusting it down toward 2 1/2 BTDC.

Playing with the idle mixture doesn't smooth it out.
I don't have a tachometer, so I have no idea where it's at, but it will stay running as I adjust the dizzy if I turn the idle up.

Now since I have so many variables here (point gap, rotor position, plug wires, plugs, idle mixture...), what's the likely cause for this wobble? I'm willing to believe that it's a vac leak, but since that would've had to have happened in it's down time while being worked on, I'm wondering what else it could be.
Dirty carb?
Bad timing?
Point gap?
Help!

I hope that is a typo and you meant to say 12 degrees BEFORE TDC. If your timing really is 12 ATDC, then you need to adjust it to about 10 BTDC

You have to use the right tools for the job. Not to be a jerk, but a tachometer is a very basic tool and fiarly necessary for a tune up and engine maintenance.

Incidentally, you are setting your timing with the vacuum advance hose unhooked form the distributor, right? And you are hooking it up to the carb and not the intake, right?

I can't adjust the lash. It's hydraulic, or so I hear. There's no adjustment screw. The head is from '81.

A wobble across the engine RPM suggests to me that you eithe rhave bad mounts or a cylinder (or two) not firing. I would verify that the plug wires are fulluy seated on the cap and the plugs.

Author:	Chetterhead [ Thu Jun 05, 2014 10:54 am ]
Post subject:	Engine wobble- vac leak or ??
I've been working on my Dart for about the last four months, just trying to replace a few things here and there, but it's mostly just left me without a driveable car. I replaced my plugs and wires (NGK's, and Standard wires), had trouble getting it going, and replaced my points, cap, and rotor (all Bluestreak). Long story short, the thing is finally running again. However, it's wobbly, and stays like that from idle to revving. Now, I don't have the best mounts, but it didn't wobble like this before, or even the few times it's fired up as I've been working on it. I checked my timing mark, and it's somewhere around 12 degrees after TDC, but it starts chugging and quickly dies if I start adjusting it down toward 2 1/2 BTDC. Playing with the idle mixture doesn't smooth it out. I don't have a tachometer, so I have no idea where it's at, but it will stay running as I adjust the dizzy if I turn the idle up. Now since I have so many variables here (point gap, rotor position, plug wires, plugs, idle mixture...), what's the likely cause for this wobble? I'm willing to believe that it's a vac leak, but since that would've had to have happened in it's down time while being worked on, I'm wondering what else it could be. Dirty carb? Bad timing? Point gap? Help!

Author:	xjarhead [ Thu Jun 05, 2014 11:35 am ]
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Double check the firing order of the plug wires. Dave

Author:	Chetterhead [ Thu Jun 05, 2014 11:37 am ]
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I'll check 'em!! Going to be out there working on it in a bit. Thanks

Author:	Chetterhead [ Thu Jun 05, 2014 12:16 pm ]
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All the plug wires are in the right place. I did spin the fan backward a little (can't go forward without a ton of effort) and this time it would go back forward just a touch when I let go of the blade, which it's never done before. It always puts up resistance as I spin it backward, but it's always held still when I let go. Now something is pushing it back forward just a little bit. I'm wondering if I have a problem in one of my cylinders now.

Author:	Danarchy [ Thu Jun 05, 2014 12:29 pm ]
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Quote: Point gap? Dwell? This is some of the best money I ever spent!http://www.walmart.com/ip/Equus-5568-Pr ... ethod=p13n I bought mine off of eBay for alittle less than $100. another tool that will make your life easier! http://www.sears.com/atd-5657-deluxe-va ... ockType=G1

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Engine wobble- vac leak or ?? https://slantsix.org/forum/viewtopic.php?t=55534	Page 1 of 2

Author:	Serj22 [ Thu Jun 05, 2014 2:20 pm ]
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Did you pull the plug wires one by one to see if it idled worse,or if one ran the same? One of my plug wires somehow malfunctioned and cylinder 5 wasn't firing at all and the engine was rocking the car like crazy till you accelerat end; Switched it to a working wire and it idled fine again.

Author:	Serj22 [ Thu Jun 05, 2014 2:21 pm ]
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Did you pull the plug wires one by one to see if it idled worse,or if one ran the same? One of my plug wires somehow malfunctioned and cylinder 5 wasn't firing at all and the engine was rocking the car like crazy till you accelerat end; Switched it to a working wire and it idled fine again.

Author:	Reed [ Thu Jun 05, 2014 2:27 pm ]
Post subject:	Re: Engine wobble- vac leak or ??
Quote: and it's somewhere around 12 degrees after TDC, but it starts chugging and quickly dies if I start adjusting it down toward 2 1/2 BTDC. I hope that is a typo and you meant to say 12 degrees BEFORE TDC. If your timing really is 12 ATDC, then you need to adjust it to about 10 BTDC Quote: Playing with the idle mixture doesn't smooth it out. I don't have a tachometer, so I have no idea where it's at, but it will stay running as I adjust the dizzy if I turn the idle up. You have to use the right tools for the job. Not to be a jerk, but a tachometer is a very basic tool and fiarly necessary for a tune up and engine maintenance. Quote: Now since I have so many variables here (point gap, rotor position, plug wires, plugs, idle mixture...), what's the likely cause for this wobble? I'm willing to believe that it's a vac leak, but since that would've had to have happened in it's down time while being worked on, I'm wondering what else it could be. Dirty carb? Bad timing? Point gap? Help! Stop. Take a breath. Get a tachometer and a vacuum gauge. Go back and verify the point gap, base timing, and plug gap before doing anything further. Verify all the plug wires are fully engaged in the cap and on the plugs. Sometimes it is tricky to get the terminals clicked into place. Incidentally, you are setting your timing with the vacuum advance hose unhooked form the distributor, right? And you are hooking it up to the carb and not the intake, right? Then set the idle speed to the correct speed and set the mixture properly. If you still have an engine wobble, check your idle vacuum and report back. If verifying the timing and fuel mixture doesn't correct the wobble, then i woudl look at valve lash and motor/trans mounts.

Author:	Chetterhead [ Thu Jun 05, 2014 4:32 pm ]
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Quote: I hope that is a typo and you meant to say 12 degrees BEFORE TDC. If your timing really is 12 ATDC, then you need to adjust it to about 10 BTDC I'm going to assume that I'm probably getting it backward. It's around 12 on the tab, toward alternator. so, the tab has about two lines, the zero, then a lot more lines. it's at 12 on the "lot more lines" side. make sense? Quote: You have to use the right tools for the job. Not to be a jerk, but a tachometer is a very basic tool and fiarly necessary for a tune up and engine maintenance. My roommate had one, then moved out. I was just looking at them, because I know I'm screwed without one. Quote: Incidentally, you are setting your timing with the vacuum advance hose unhooked form the distributor, right? And you are hooking it up to the carb and not the intake, right? Yes to everything on that. The distributor holds vacuum. I can't adjust the lash. It's hydraulic, or so I hear. There's no adjustment screw. The head is from '81. [/quote]

Author:	wjajr [ Thu Jun 05, 2014 5:10 pm ]
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Quote: I can't adjust the lash. It's hydraulic, or so I hear. There's no adjustment screw. The head is from '81. If this is true, than make sure all rockers are passing oil down to the hydraulic lifters. If one or two of the lifters are not fully filling with oil from a lack of flow those valves won't have full travel.

Author:	Reed [ Thu Jun 05, 2014 7:37 pm ]
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The year of the head doesn't matter, the lifters, cam, pushrods, and rockers arms do. If the camshaft is hydraulic then yes, you cannot adjust the valve lash. However, just because the head is an 81 doesn't mean you have hydraulic lifters. Is the whole motor a 1981 motor? If just the head is 1981, did whoever swapped the head on leave the 1981 hydraulic rocker arms on the head but keep the mechanical cam, lifters, and pushrods? Have you read THIS thread? If someone put the 1981 head and hydraulic rocker arm assembly onto a 76-earlier mechanical lifter Dart engine, then you may need to install rocker arms that are adjustable and set your valve lash.

Author:	Chetterhead [ Fri Jun 06, 2014 11:55 am ]
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Sorry, it's an 85 engine. Forgot that part. I'm going to try switching my plug wires back to the original ones and see if there's any change. Would having the point gap off make it wobble? I can't even remember what they're set at now. Since you can apparently set them between 17 and 23, what is it that dictates where you set them? Is it a matter of dwell, or is it variable depending on available power, or?

Author:	Chetterhead [ Fri Jun 06, 2014 11:57 am ]
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Also, I had not read that thread, but I'll go over it in case there's something I should know.

Author:	Reed [ Fri Jun 06, 2014 11:59 am ]
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A wobble across the engine RPM suggests to me that you eithe rhave bad mounts or a cylinder (or two) not firing. I would verify that the plug wires are fulluy seated on the cap and the plugs.

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Author:	Chetterhead [ Sat Jun 07, 2014 11:49 am ]
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Quote: A wobble across the engine RPM suggests to me that you eithe rhave bad mounts or a cylinder (or two) not firing. I would verify that the plug wires are fulluy seated on the cap and the plugs. I agree with you. I changed back to my original wires and nothing changed. I'm going to look at my plugs and manually turn my engine and make sure the pistons are all moving and nothing's obviously broken.