Hi guys,

New to the forum. Early this year, I bought a 1980 Chrysler LeBaron with what I believe to have 52,000 original miles. The car sat for some time. Minimal to no rust, completely stock(?)*

Since I've owned the car, it's never run properly. With the original equipment, it would barely stay running and make an intermittent "squealing" noise at idle, frequently stall when put into gear, and die when pressing on the accelerator.

I rebuilt the original Holley 1945 and rebuilt a core from eBay, no luck with either carburetor. I discovered the exhaust manifold was warped, and I was looking to drop the 1945 for a better carburetor, so I opted for a new Dorman exhaust manifold, Offenhauser 4BBL intake, Edelbrock 1904 500CFM carburetor, Lokar throttle/kickdown cables, and Remflex gaskets.

After completing the modifications, the car still had somewhat of a rough idle, but had improved, and the car was now drivable. I believe idle vacuum was 22 inHg, but rapidly fluctuated. I drove it for the first time and put in a fresh tank of gas. Seemed to drive okay while feathering the throttle, but lacked power all around and bogged at heavy throttle. Tried driving it the next day and it wouldn't stay running. Sounded like a tractor, stumbled, and stalled at mid-WOT both at idle and in gear. Idle vacuum was 15-16 inHg, needle rapidly fluctuating +1/-1 inHg.

Initially, the engine would also intermittently "hitch" and the vacuum would drop 2 inHg or so due to what I'm assuming was a sticking valve. The oil level was just under the fill line and black. Changing the oil and adding Lucas Heavy Duty Oil Stabilizer appears to have fixed this.

I replaced the original ignition coil as it was leaking oil, ballast resistor, spark plug wires, spark plugs, distributor cap, rotor, PCV valve, etc. It looks like the previous owner installed a new distributor pickup, so I left it in place, but I bought an extra. The ignition module and voltage regulator were also replaced by the previous owner.

Last night I connected a timing light and checked the vacuum. The timing jumps between 16 and 10 degrees BTDC, but would periodically smooth out at about 12 degrees BTDC. 8 degrees BTDC causes the engine to stall. Vacuum advance disconnected. Vacuum was 5 inHg, rapidly fluctuating. Idle is set to roughly 800 RPM, fluctuating between mid-low 700 to mid-high 800 RPM range. Tuning is extremely difficult given the constant fluctuation for all variables.

I'd imagine it's possible, but unlikely the valve guides are worn as the vacuum fluctuation would indicate, although that would be unordinary at this mileage. I haven't adjusted the valve lash and I haven't verified TDC on the balancer yet to find out whether or not the balancer has slipped or the timing chain has skipped a tooth. There is quite a bit of smoke that comes from the crankcase breather that I'd imagine would otherwise be eliminated by the PCV valve.

I intended for this car to be my daily driver while I paint the frame of my 1988 Dodge Dakota, but I can't seem to figure this out. Vermont winters are brutally cold, and I don't want to have to put this on hold until spring, especially since that would mean exposing my truck to corrosion for another season. All in all, any help in diagnosing this engine would be greatly appreciated. Thanks in advance.

As an additional detail, this car has some parallels with the 1980 Dodge Mirada Concept in this article from BangShift.
https://bangshift.com/general-news/car- ... -show-car/

• The VIN does not follow the standard Chrysler VIN format for 1980 as the year is represented by an "A" rather than a "0".
• I have the same Creative Industries, Inc. keychain. Creative Industries was known for building a number of concepts for the Big Three auto manufacturers.
• I bought the car without a title from an individual who claimed to be the original owner. Assuming the vehicle was a concept, or subject to an auction via Chrysler, no title would be present.
• Minor differences at first glance compared to the 1980 Chrysler Factory Service Manual.
• Custom interior door panels are present on the Mirada Concept. My car's door interior panels are missing. The previous owner claims they were stolen. (If anyone has panels, I would be interested in buying them.)

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Alex

1988 Dodge Dakota - 3.9L/238 LA V6, A-998 3-Speed Automatic
1980 Chrysler LeBaron - 3.7L/225 Slant Six, A-904 3-Speed Automatic

At this point, I think what I would do is to confirm whether you have hydraulic lifters or solid lifters, and do a compression test.
Also, does this car have a "lean burn" computer? If so , they were noted for the ign timing circuit malfunctioning.

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Charrlie_S
65 Valiant 100 2dr post 170 turbo
66 Valiant Signet 170 nitrous
64 Valiant Signet
64 Valiant 4dr 170
64 Valiant 4dr 225

Thanks for the reply, Charrlie.

I've got solid lifters. I believe all Slants went to hydraulic lifters starting in 1981.

Compression test is next on the list. Hopefully I'll have time tonight before work. I'll post back with results.

This car was not originally equipped with Lean Burn.

Happy Thanksgiving, everyone!

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Alex

1988 Dodge Dakota - 3.9L/238 LA V6, A-998 3-Speed Automatic
1980 Chrysler LeBaron - 3.7L/225 Slant Six, A-904 3-Speed Automatic

Squealing? Could be you have a vacuum leak somewhere and that will cause all kinds of issues.

Yes to the lean burn.You might as well assume it needs upgraded /replaced. This is not hard or expensive really.
I would guess that a thick oil additive is the opposite of what this car needs if it has sat for a long time and has low miles.It may need something to clean out the engine varnish/sludge...etc. run through it. Good luck and post back!

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2 Mopars come with Spark plug tubes. One is a world class, racing machine. The other is a 426 CI. boat anchor!

12.70 @ 104.6

Thanks for the reply, Rick.
I initially suspected a vacuum leak while the car still had the original equipment installed. The exhaust manifold was warped, so I had assumed the intake manifold may have also been warped and causing a vacuum leak. The OEM-style steel gaskets don't seem to seal very well, either. I ended up installing a number of new parts, the full list is in my initial post. (New intake and exhaust manifold, carburetor, Remflex gaskets, etc.) I figured I'd opt for some upgrades. The squealing has since been eliminated. I sprayed around with carb cleaner and haven't noticed any change in RPM. All vacuum ports on the carburetor and intake manifold are capped aside from the vacuum advance and PCV valve.
The car is free of Lean Burn. Standard electronic ignition.
At the time, I wasn't sure of the current condition of the engine, so I opted for Shell Rotella T4 15W-40 and the Lucas Heavy Duty Oil Stabilizer. I was hoping for a quick fix to stabilize the vacuum readings assuming a valve was sticking, but yes, I agree, some cleaning additives aren't a bad idea. Another oil change or two, new filters, synthetic oil, Marvel Mystery Oil, and some Seafoam might be beneficial. The valvetrain didn't appear to be too bad.
I appreciate it, will do!

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Alex

1988 Dodge Dakota - 3.9L/238 LA V6, A-998 3-Speed Automatic
1980 Chrysler LeBaron - 3.7L/225 Slant Six, A-904 3-Speed Automatic

That heavy of an oil (plus the "stabilizer"doesn't help) is hard on the oil pump drive gear and cam gear. Get that heavy oil outta there and skip the Lucas crap

Check the valve adjustment

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Charrlie_S
65 Valiant 100 2dr post 170 turbo
66 Valiant Signet 170 nitrous
64 Valiant Signet
64 Valiant 4dr 170
64 Valiant 4dr 225

Be very careful and attentive in using cleaners and such in the crankcase.. I've got a buddy who decided to use synthetic oil in his 99 taurus. It cleaned stuff up so much the filter plugged and went into bypass. The lifters started complaining and that is when he realized something was up.. it is now running great on 5 cylinders...


After you get the compression #'s and check the valve adjustment, it seems like turning your attention to the ignition system and why you are getting ignition timing bouncing around from 8* to 12* BTDC would be a logical next step.

Echoing Volaredon I run 5W-30 here in VT year around. 15W40 is too thick below 50* in my mind, and adds needless stress on the oil pump drive gear which is arguably the weakest link in the slant six chain.

No. (Seriously, no.) Engine oil does not need to be "stabilized" (which doesn't actually mean anything).
One can hope. Eventually—once the root cause(s) of the problems are found and fixed—you will then have to deal with the poor driveability and lousy fuel economy that come with putting on a much-too-big carburetor.
Yes, and it will also be a good idea to service the oil pressure relief valve to make sure it's doing its job, as described in these two threads: thread 1, thread 2.

Your fluctuating timing and vacuum suggest a slack timing chain and/or faulty distributor.

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