Classic Auto Mechanics - Needing help with '77 Lincoln Continental Mark V

I know there are some mechanics of the Ford persuasion on this board and I'm calling out for help with something I just can't track down.

It's a 1977 Lincoln with Ford 460 motor and C6 trans. Motorcraft 4bbl carb and everything is stock except that the timing is restored to the correct pre-1972 position.

I picked this up about four-months ago and as I've driven it's gotten worse and worse to the point it's now undriveable.

In July, I'm in Wyoming and I find this. The mornings there were about 57° and the days up to 90°.

I bought it after it had sat for three-years. Drove it home, rebuilt the carb with new parts, replaced the cap & rotor, plugs and wires, all fluids, set ignition timing and it ran right.

I took it out for a few nights. On the highway it would just cruise like a dream. It had all the power in the world. Doing 40-60 drop-gear accelerating would raise the hood at least 6" up and the tires would sometimes come unhooked.

It started so easily in the mornings that all I had to do was flick the key for a split second and it would jump to life and idle so well it was too good to be true.

One day I was driving just after noon and was braking at a stop light when suddenly, without warning, my oil light came on to warn me I lost pressure. Sure enough the brakes and steering were gone as well. It died. Out like a light.

I started it again and it took a little long to crank. I parked in a nearby car park and it happened again.

I waited five minutes and it started up fine, so I drove home and started wondering what the hell that was about.

Well now and then it would just die. The cranking times increased too.

I had to leave Wyoming at the beginning of August. I headed out towards Texas and about twenty minutes on the road I started getting some horrible racket from my exhaust. It sounded like a little machine gun blapping. I learned it would do it if I maintained a certain throttle position. If I tried to accelerate or decelerate, it would eventually stop.

In the higher altitude parts, I would adjust the timing to compensate and it would accelerate better, but that blapping in the pipes stayed with me until New Mexico and when it would happen I would practically lose power, the RPM's would drop almost to the point of dying and sounded very hollow.

I got to Texas and now it's bucking and dying constantly.

Sometimes it would lose RPM then would wa-wa (if you're familiar with records) and sputter out, other times it was off like a LIGHT. Even on the highway I have had it shut off.

I drove it from Dallas to Austin and back without any issue, but at both places in stop and go, it was just a hair-pulling experience. It got to the point it wouldn't even start in the morning at all. Sometimes it wanted a little choke, sometimes none at all. Sometimes it would start with the TSP off, sometimes it wanted it on. Most days I would have to wait TWENTY MINUTES before I could apply throttle without sputtering out! Yes, the choke IS opening automatically.

Now I just don't drive it. The last time I did, it died on a 30-minute highway ride three times. The last time, it simply would NOT start. It would only hit once or twice but never really start. Weird thing is that there was power steering fluid puddled in an area that was just a MESS. It's like it was coughing the stuff up, but my power steering fluid level is fine...

What is this witchcraft?! How could this have happened?

Now I'm staring at the thing wondering how cool it would be to watch it burn.

TL;DR

Here's the info I've concluded:

Number 4 cylinder is NOT running. Unplug #4 and it makes practically no difference.

All cylinders are exactly 150psi, air filter off and throttle wide open.

No lifter tick.

No vacuum leaks from anything attached to the ports on the EGR plate or carb. I have taken the hoses off of all vacuum ports directly at the source and plugged them.

I did spot a crack in the intake manifold gasket that was sucking in carb cleaner. I replaced the gasket and glad I did, both cylinder banks did have obvious carbon tracks where vacuum was leaking.

None of the pushrods were bent.

There is a squeaking sound coming from my exhaust. Sounds very similar to some vacuum leaks I've heard on motorcycles. It's a chirping pattern. If you hold a piece of paper over the exhaust, now and then it will suck it inward. Keep in mind I have a 2-2 exhaust with an H-pipe and Magnaflows.

Currently:
While running it will idle ok when cold even though #4 is dead.

It constantly shudders, at times it begins to buck.

Once hot, RPM will drop from 900 to 650 VERY suddenly, within an instant, then sometimes recover just as quickly or die altogether.

Watching spark on all other cylinders with a little inline spark light, I never lose spark to ANY cylinder.

No spark leaking to another ground source.

Watching the timing on each cylinder (my flywheel is marked with 8 TDC marks) all are perfectly alike to one another and does not fluctuate. It's a Duraspark II and is rock solid in its advance at idle.

Voltage is maintained at 14.3v and when the idle drops to 650 may go as low as 13.3.

Parts I've swapped with a known working 1978 Mark V with the same motor:

Plug wires

Distributor

Ignition control module

Coil


At this point I'm almost certain I have multiple issues. Sometimes it dips in RPM's then dies, other times it shudders horribly and RPM's wa-wa, and then on the highway it can just go out like a light or rev with a hollow sound but no power...

Thanks to anybody that's read this far at least!

Some glamour shots because I'm conceited.

I had a F250 with a 460 and the Motorcraft 4300D carb. I don't care for the carb.
Rebuilt mine and still ran bad. Ended up replacing it with the Holley 4180 off my 351 HO.
ran better but still not up to par. Also I'm not a fan of egr systems. They can cause
some of the symptoms you described. My '94 Ranger recently started to miss/chug
just off idle to around 1900 rpm. Unhooked and plugged the vacuum line. Runs fine ever
since. I would start there. How was the cam timing corrected and how long ago? Timing
chain could be worn out. Check your timing and rev up the engine to see if it dances around.



.

Did you empty/clean the gas tank? If it has a fuel filter, blow through it backwards and see if any junk comes out. I'm curious if maybe some crap got in the freshly rebuilt carb.

The sucking/chirping you describe sounds like it may be sucking air through the main bearing. If that's the case, it's because the PCV is misrouted or clogged, forcing the vacuum to draw through the bearing seal. PCV are a good thing, since they keep moisture out of the engine case. Many, if not all of the issues you describe, can be sourced to issues with the PCV system. Do you have vacuum advance? If so, I just want to make sure you're setting your timing with the vacuum line to the distributor plugged. Where are you taking your vacuum readings from: Carb or intake?

Ok so where would I start with that?

This makes a lot of sense because when I first got the car it wouldn't leak a DROP of fluid. As things have gotten worse, so has the main bearing oil leak I have.

I'm taking my vacuum measurements through the intake manifold vacuum port.

What would this have to do with #4 being a shit?

PCV is a recirculating system, but it needs to draw clean air from somewhere. Typically, there is a filter in one valve cover and the PCV valve in the other. It's not uncommon for the PCV valve to go bad or clog with old oil. You can test it pretty easily, but they cost less than $10. The valve cover that gets the valve is always partitioned to prevent oil from getting up into the valve. I've seen many times where people put the valve on the wrong cover. I've also seen many times where people run two valves where one should be the filter. The filter often has a vacuum port, so people's confusion probably comes from there. First thing I would do is trace the system and make sure it's routed in a way to allow clean air to enter the system and vacuum to exit the case. The exit is always through the carb so it can be re-burned- either through the air filter or through a port on the base plate or throttle body. It usually enters through the valve cover. Many people are confused by the PCVs purpose as an emissions control. While it does partly do that, in acting like a recuperator, its main purpose is to burn moist air from engine oil.

How early is it for you, dev? I'm pretty sure now we're talking about the PCV

My PCV was replaced once the problem started.

Vacuum is supplied from the rear of the carb base. It goes directly to the PCV attached to the valve cover. On the other valve cover, an oil filter cap with a built-in filter and hose attaches to the air cleaner housing.

So how would I test if this is the issue? I understand if there is no relief for the block, the blow-by can blow seals. But if the vacuum from the carb has no where to pull fresh air from, the negative pressure can start sucking oil. My plugs all have traces of oil...

Redliner said:

How early is it for you, dev? I'm pretty sure now we're talking about the PCV

Click to expand...

Good timing. I was just about to correct myself. Ha.

There, all fixed.

With the engine running, pull the pcv out of the cover. You should get a significant rise in idle and you should feel vacuum at the valve. And to a previous question, a bad pcv system will cause issues with spark, especially if its causing blowby or fouling. Having a pcv connect to the oil filler with a connection to the air filter means you have a closed system. They are much more effective as an emission control.

Also, is the brake booster hooked directly to the intake or is it running through a "T" and connected to the carb throttle body?

We used to block off the vacuum pipe to the EGR with a ball bearing so they looked like they were hooked up.

The symptoms could be a number of things but I'd start with the fuel tank and breather (carbon can) system and then replace the fuel filter and check the float bowl for rust. It does sound like a fuel blockage, but could well be the PCV or EGR systems.

Cool ride.

Thanks teaz.

The fuel tank and vent are both new and tested to work. I will however put a clear inline filter going to the carb to insure fuel is being delivered constantly. My carb seems to be weeping around one if the gaskets that seal the bowl.

Dev, my brake boost is provided hydraulically

I have vacuum at the PCV connection. So if I do leave the PCV bung open to atmosphere, and it doesn't improve the condition....?

Here's the PCV setup.

First, the filter/oil cap that feeds from the air cleaner housing.

Then the PCV end.

I keep having to go back and read your opening, so forgive me if I'm leaving stuff out. You replaced the distributor, but did you also replace the vacuum canister? The pcv system can be a culprit with many of these issues, but so can your vacuum advance. Is it timed with the vacuum advanced disconnected from the carb and plugged? Also, is the vacuum advanced connected to port vacuum (carb) or manifold vacuum? It should be connected to port vacuum. The motor loses vacuum as it goes up in rpms. The chirping sound still suggests there is an issue vacuum being sucked in through the main seal. If you have a stethescope, when the motor chirps in idle, get under there and put the scope on the cover over the torque converter. It'll confirm whether the chirping is coming from the main seal.

Stalling after it gets hot sounds like the carb is flooding. Excessive fuel pressure, bad floats, misadjusted floats, bad needle and seat, or junk in the needle and seat would cause it to flood after it heats up.

I'm starting to suspect the flooding since the carby is drenched in old fuel now. But that wouldn't explain #4 being completely dead with equal compression. #4 also has a pretty clean plug, no different than the others. Maybe the intake valve isn't getting enough lift, but wouldn't that hurt compression?

Timing is set with the advance hose plugged. The source vacuum is from both manifold and a ported source on the carb. These feed to a vacuum switch which changes from manifold to ported carb source once the engine is hot.

The chirping comes from the end of the exhaust pipe. I can hear it resonating inside and it coincides with the pipe sucking air back into it.

Here's something odd.

There is a port on the exhaust side of both heads that allow air to be injected directly into the exhaust. I plugged the air injector, so exhaust wouldn't be able to go back up through the check valve and into the air pump.

The pipe that connects into this port on the head is making a flappy sound. At first I thought it was a ticking lifter, as it was almost indistinguishable, but when I put a hose on my ear to trace it, it's making that flapping sound from around that pipe. Guess that's leaking too so I may as well tackle that first. Shouldn't be the issue though.

Edit: How ****** stupid can a ***** operating system be to ****** replace. "Shouldn't" with ********** "Should" auto-********matically?! **** ****.

Perhaps the issue with #4 is a flat spot on the cam. When you were checking for bent pushrods, did you confirm that all valves were opening and closing?

4eyes, thanks I thought about that. Could be intake or exhaust or both. I'll pull the cover off when I'm not working.

Here's another thing to look at. Those year Fords had terrible issues with the Electronic ignition "black Box" A box that went bad would not completely quit. It would work until it got hot and then it was like running out of gas. Crank and crank, no start. You sit for 15-20 minutes, and the darn things starts like nothing was wrong.....As time goes on (not a long time either), the box gets hotter quicker and comes back slower. Back in those years (I was a Professional Mechanic then) I recommended friends and family carry a spare black box, and if the car mysteriously quit, swap in the new box.

I suggest a new black box (ICM - Ignition Control Module http://www.rockauto.com/catalog/moreinfo.php?pk=385933&cc=1188244&jnid=439&jpid=6 )and if it works, get another as a spare, keep in the trunk.

I warmed up the car and waited for the motor to start bucking. Then I immediately threw in a new box, one that came recommended from a 460 guy, and it continued exactly the same way... I still have the old box laying here as a working spare.

Thanks though.

It's so weird that 4 seems good by all measures. Maybe just the valves or lifters or pedestals etc.