1978 Lincoln Continental Coupe

[TireSmoker]

You guys make my wrenching more fun.

That's the whole point of this place.

-Dave

[Maverick]

We had a friend visiting yesterday. He and I installed the secondary fuel block with power valve and secondary idle mixture screws.. Thought I had a 10.5 power valve to match the one in the primaries but all I found in the spare parts was a 6.5. Replaced the secondary jets , 99 down to 90. WXO came over and we took it out for a test. The secondary power valve did the trick, idle was pretty good with no other changes and cruise and WOT were both fat.

Replaced the 73 primary jets with 68s and cruise is now around 15 AFR and WOT is 11.5 - 12. Could go leaner on secondary jets but the Lincoln will probably be neglected for a while since there are more exciting things happening to the El Camino.

[Maverick]

WXO recorded videos of our test on Monday. We're pretty happy with the results. Had fun doing it too.

WOT test: https://youtu.be/0In_MsXFQ7M

Cruise test: https://youtu.be/ExVSUrs01Zc

[Maverick]

Taking a little break from the El Camino and plan to take the Lincoln on a little cruise, lunch, and private classics collection tomorrow with a local car club. The awful drone after spending a day and $4XX to get the exhaust fixed was a downer. WXO and I planned to take both the Lincoln and the El Camino to the event but I'm not eager to take the El Camino very far till we get the carb tuned.

The Lincoln starter has been balky when the engine is hot but never failed to start. Today after a 30 minute drive, it did not want to start. This time is sounded more like a weak battery or starter than kick back from early timing. I already replaced the starter with a Powermaster mini and the battery with an Interstate with good rating (don't recall the specifics). The header by the starter already has wrap on it and today I added insulating wrap on the starter.

If/when it balks again, I'll pull the coil wire and try it again to get a conclusive answer on pre-ignition vs weak starter or battery.

[Maverick]

Came home from the cruise, etc., with the engine at 195*. Shut it off and it restarted, no problem. I'd like to think the hot start problem was solved by the starter insulation but am withholding judgement till it behaves on a HOT day. Was only in the 70s today.

[Maverick]

Was about 90* today. Came home from a car show with engine at 205*. Shut it off and started with no balk.

[Maverick]

I haven't been driving the Lincoln lately because the AC isn't working. Last summer, the evaporator was freezing up maybe because the POA valve is still calibrated for R12. I contacted Classic Auto Air (where I bought the Maverick Under Hood Kit) in Florida to get the POA recalibrated but they suggested I replace it with a POA Update Kit that eliminates the POA with a straight thru tube with pressure switch to cycle the compressor rather than throttle the low side to prevent evaporator freeze up. I got the kit and it sat on the shelf till this week when WXO and I installed it. There wasn't much refrigerant in the system so there must be a leak somewhere.

After installing the POA eliminator, we tried charging the system but the suction line was hot and pressure was so high the refrigerant would only go in VERRRRRY slowly. The pressure in the suction line was very close to the vapor pressure of R134a at the temp of the line. We have two theories:

1. There's a restriction preventing refrigerant flow yielding high pressure on the suction side.
2. The high temp (higher than the temp of the R134a can) in the suction line is preventing us from getting enough refrigerant in the system to cool the evaporator and suction line and get the suction line temp (and vapor pressure) down so it will take refrigerant.

I favor #2 but we're taking it to a tech on Wednesday. He's supposed to be familiar with these old systems. Hope he can psych it out.

[Maverick]

I hate to admit I can't do something. Still had a couple of ideas so the appointment with the AC tech was cancelled. This morning I was working on theory #2, i.e., there isn't enough refrigerant to keep liquid at the expansion valve so vapor was passing thru with not enough expansion to cool the whole evaporator and suction line and bring the suction pressure down. This morning I tried one more time to charge the system. Worked OK for a while, with suction pressure as low as 40 PSI but then pressure and temp in that line rose preventing charging.

OK, one more theory. Maybe the expansion valve is partly clogged. That might cool the valve but not much more. Ordered a $15 expansion valve yesterday but it still hasn't shipped. We'll see if a new expansion valve will fix it. If not, I'm out of ideas.

[Maverick]

We disassembled the entire AC system and flushed everything except the compressor, which all the online advice says "don't do". We replaced the expansion valve and all o-rings and coaxed 2 16 oz cans of R134a in. Some improvement in the behavior but it's still not right. My latest theory is the condenser is partially blocked causing most of the expansion to occur within the condenser rather than at the expansion valve. There was a substantial drop in temp from one condenser loop to the next.

So, I ordered a new condenser. The original, serial loop tube style, is available on ebay for $295. Lots of advice online that a parallel flow condenser will compensate for the less effective refrigerant when converting from R12 to R134a. And, when flushing everything, there was not much flow thru the condenser. So, a 16X29.5" universal parallel condenser https://www.summitracing.com/parts/vta-037030-ovr was ordered from Summit along with a universal drier/hose/fitting kit https://www.summitracing.com/parts/vta-31700-vbd Order total also $295. If THAT doesn't do it the only thing left is the compressor. Hope that doesn't have to be replaced.

We'll be working on it next week. This week I'm installing a trailer hitch. My 2002 Explorer is having some non-fatal problems but could croak any day. At my age, 80 in March!, I don't think I need to buy another SUV so maybe the trailer behind the Lincoln will do for a while. The hitch has me fantasizing about a cross country trip in the Lincoln with a tiny camper trailer in tow.

I got a used, universal hitch for $25 and cut it up to make it work. Took it to a great welding shop in Raleigh that welded it all together for $60. Was able to hide the hitch pretty well.

[GMJohnny]

The trailer wiring should be painless on your Lincoln because of the vintage.
I like the cross country idea!!

GM

[Maverick]

Ah!! Glad whatever was happening on TS.org yesterday deleted my last post. We hadn't solved the mystery at that point.

Good news is that WXO concluded that the AC just needed more refrigerant. The control valve on the heater hose is getting vacuum, staying open, when the dash control is set to AC. That kept the evaporator, and therefore the suction line, temp high and, therefore, pressure so high it didn't want to accept more refrigerant. Solution was to shut off the heater hose and continue to coax refrigerant in. AC is working!!

Still have two issues to sort out. There's a mysterious second wire feeding constant power to the compressor clutch so the compressor can't cycle. And, gotta figure out why the heater hose control is getting constant vacuum. Both might be related to the Automatic Temperature Control (ATC) option that gives lots of guys trouble. Hope the vacuum switch in the dash control isn't bad. Have some studying to do ...

[Maverick]

Been reading about the Automatic Temperature Control (ATC) on the Lincoln. Turns out it's behaving as designed except that maybe the water shut off is not shutting off under full vacuum. I'm making a record of the answers here in case I need to refresh my memory. Read on if interested.

First there's that mysterious wire feeding continuous power to the compressor clutch. Turns out, it's supposed to power the compressor clutch except when the outside (ambient) temp is cool or cold (maybe below 50-60*F). There's an ambient temp sensor behind the grille that interrupts power to the compressor clutch whenever ambient temp is cool or cold. Otherwise, the compressor runs. (The original system didn't cycle the compressor to avoid freezing the evaporator but rather ran the compressor continuously and throttled the suction line to prevent evaporator freezing) Purpose of running the compressor even when some heat is required is to dehumidify the cabin air.

Then there's the vacuum supplied to the water control valve when the system is off or in AC mode. Also working as designed. Vacuum is supposed to shut off coolant flow to the heater core rather than open the valve as I had assumed. Why the input and output hoses to the heater core were both hot when we were trying to charge the AC system, I'm not sure. That valve was replaced when the engine was installed. I'll have to test it some day.

And, we didn't understand why both suction and liquid lines showed high, nearly equal pressures when, in the end, the compressor was shown to be working well. When we stopped adding refrigerant, high pressure line was over 300 PSI and the compressor belt was beginning to slip. Obviously, the compressor is pumping. Answer might be provided by the diagnostic info. One reason for showing high pressures in both suction and liquid lines is "Engine Overheating". Engine temp got up around 220*. Maybe the under-hood temp is high enough so the liquid line contains vapor and it's blowing thru the expansion valve pressurizing the low side too?

Diagnostic info gives another reason for high pressure on both sides: insufficient insulation on the expansion valve's temperature-sensing bulb. I had it swinging in the air to make sure the expansion valve stayed open.

One mystery remains: there's another power supply wire to the AC clutch which I assumed was the one that was powering the clutch. Not so. That's the one that got the suction line pressure sensing switch in the POA Delete kit to cycle the compressor. This second wire isn't shown in any of the shop manual diagrams so I don't know what it's for. Whatever it's for, it will remain in place, with the pressure sensing switch in series with the clutch. Power from both wires will be interrupted by the suction line pressure sensing switch.

[Maverick]

I ran an 870 Street Avenger from Holley on my Caddy. It was not nearly as hairy as your Lincoln motor, weighed about the same, and I would always be running 99+ MPH. It's a nice blend of streetability and top end pull. I would make the switch. I believe that motor will come to life once the cam comes in and the secondaries open.

-BP

BP and others said, based on the 1/4 mile ET and MPH, it would do better with a bigger carb. Poking around on the Internet, I found this which corroborates what you guys are saying. http://www.4secondsflat.com/Carburetor% ... Charts.htm

They're recommending an 850 CFM, as opposed to the 750, carb for my 521 CI, 5500 RPM engine. Wish I had gone with the QF 850. It's too expensive to switch now. One of the aftermarket EFI systems would be fun. Already have an in-tank hi pressure fuel pump. Its something to think, or maybe dream, about ...

[Maverick]

Checked with WALPRO to see if their GSS307 in-tank fuel pump that already installed is appropriate for the SNIPER EFI. Sadly, it's 47.3 PSI isn't up to the 55-60 required for the SNIPER. Could install a pressure gauge before the regulator to see what pressure its actually producing. Installing a high pressure, in-tank fuel pump is probably the biggest job in the TBI EFI install. Hoped that issue was handled.

[Maverick]

I ran an 870 Street Avenger from Holley on my Caddy. It was not nearly as hairy as your Lincoln motor, weighed about the same, and I would always be running 99+ MPH. It's a nice blend of streetability and top end pull. I would make the switch. I believe that motor will come to life once the cam comes in and the secondaries open.

-BP

BP and others said, based on the 1/4 mile ET and MPH, it would do better with a bigger carb. Poking around on the Internet, I found this which corroborates what you guys are saying. http://www.4secondsflat.com/Carburetor% ... Charts.htm

They're recommending an 850 CFM, as opposed to the 750, carb for my 521 CI, 5500 RPM engine. Wish I had gone with the QF 850. It's too expensive to switch now. One of the aftermarket EFI systems would be fun. Already have an in-tank hi pressure fuel pump. Its something to think, or maybe dream, about ...

Here's another source that says the 750 carb on the 521 is too small.

http://www.superchevy.com/how-to/148-04 ... arbs-test/

They suggest a 750 carb for a 383 SBC that's very similar to the one we put into the El Camino. If 750 is right for the 383, it has to be too small for the 521 in the Lincoln.

I still dream about an aftermarket EFI on the Lincoln but it runs so sweet now I'm reluctant to mess with it. However, if it would get it equal to that TB SS, ...