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1972 Lincoln issues
#1
I just got my 72 Lincoln Mark IV out of the shop after it's been sitting for a few years. It's had a good bit of electrical gremlins that I've been working on for years now, and I think I've finally got most of that taken care of.

Well the last couple weeks, I've been taking it out on test runs making sure everything's ok with the car and that it's good to go. The only problems I'd really had during these drives were a very slight miss occasionally, and sometimes when you get on the gas hard at lower RPM's, the car will hesitate, kind of sputter, and backfire before accelerating. Short of that, it idles smoothly once the engine's warmed up and runs and drives fine. Last Saturday night, I took the car out and cruised with friends for about one and a half hours as kind of a final test-run, and the car did fine (was still doing the symptoms described above, however, but no major issues to report). Then Sunday afternoon, I took the car into town and had only been driving it maybe 20-30 minutes when the car just turned off. I coasted to the next light and the car cranked back up just fine, but when I put it back into Drive and hit the gas, it died immediately. So I pulled it off the road, and again, it would crank back up with no problem, but as soon as any load was put on the engine (put into gear or opening the throttle), the engine would die. So I got it towed back to the house where a buddy and I tried to diagnose the problem. With the air cleaner cover assembly off the car, I tried to crank it, and it shot a good flame out the top of the carb. At that point, we both thought maybe the car had jumped timing somehow. So I left the car alone for a couple days, then a few days ago, I went out and decided to see what it'd do. It cranked right up, idled fine, and had no issues when put into drive or revved up. I took it up and down the driveway (about 1/2 mile roundtrip) with no problems whatsoever.

So now I'm kind of baffled as to what the problem is. The car has the factory 460 big block in it. The carb is rebuilt (factory 600 CFM 4 barrel) with a new air cleaner, it has a points-style ignition system with vacuum advance. I put this here rather than in the Lincoln Tech forum because I figure this isn't a really make/model specific issue. It seems like more of a general ignition/timing/carb/vacuum/valve/etc type problem. I'm also pretty certain the car does need a tune-up (plugs, wires, etc), but could that cause the problems I'm experiencing? Thanks in advance. Any and all help is definitely appreciated!
Formerly Custom72Continental



1996 Jaguar Vanden Plas, champagne w/ cream interior

1993 Lincoln Mark VIII, black w/ black interior

1972 Lincoln Mark IV, green w/green interior

1994 Honda Accord, built JDM H22A swap - SOLD

1988 Ford Crown Victoria LX - For sale
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#2
How long ago was the carb rebuilt? Just curious, but the hesitation etc. that you mentioned makes me wonder about the accelerator pump. Even if the carb was redone recently with an old kit, the pump membrane might not want to play nice with ethanol.
My '75 Town Coupe had a similar issue years ago, and an Edelbrock Performer cured it.
Yours would be easier to deal with w/o the EGR plate etc.
Also you might want to check the gap / dwell angle on the points (.017 OR the thickness of a matchbook cover). Does that thing have a dual diaghram distributor (2 hoses to the vac. module on the dist)?
My Perfect 5th Vehicle Would Be A Towtruck

'90 LSC/SE, Black on Black in Black, 347", T5, springs, ground effects.

'94 F150 4X 306, B303

'70 MK III, 76 K miles, pretty but has issues

'01 Durango, the wifes grocery getter.

Previously: '66 Cont'l Coupe, '75 Town Coupe, '79 MK V, '83 MK VI, '86 Cont'l, '94 Cont'l,

'89 MK VII BB

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#3
Try looking over the ignition system really good. Sounds like an Ignition breakdown somewhere in the distributor, coil wire or coil. Ignition spark demand is highest under load. Ohm out all your igniton wires to find and open wire. Old ford coils are known to breakdown with age. Check for burnt points.

If you need timing/dwell specs, I have an old motor manual that has them.

What carburator is on this? (the motorcraft/holley one?)
ASE Master Tech with 15 years experience


Daily Driver: 1994 GMC Sonoma, Extended Cab, 2WD, with the 4.3 V6 Vortec.
Future plans/projects: Finishing that darn 64 Malibu SS
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#4
I'd try a new cap. But, I have heard of weird problems going back the a bad coil. Did the car have any spark when it would not run at all? Was there a good supply of gas squirting into the carb when you looked down the carb and opened the throttle?
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