Amc Eagle FAQ

From BluWiki

Contents 1 Quick Links 2 Engine and Routine Items 3 First improvements 4 Major upgrades 5 Emissions 6 The Four Wheel Drive System 7 Fuel Delivery 7.1 Basics 7.1.1 Overview 7.1.2 Carburation 7.2 Weber 7.3 Hesco MPFI 8 H/O Head 9 Wheels and Tires 10 Suspension 10.1 Control Arms 10.2 Springs 11 Body 11.1 Misc 12 Engines 12.1 Stock 12.1.1 4 Cylinder Differences 12.2 Interchange 13 Transmission 14 Miscalenous 14.1 Rear defroster

Quick Links

• Eagle Reference Tables
• Vacuum Diagrams
• MCU

Engine and Routine Items

What to check first

Chances are that your "new" Eagle has been sitting around for a while somewhere, and that's why someone decided to sell it. It probably got less maintenance in that last period of time too. You may want to go through as much of this as you can before you even move it off the lot.

Resist the urge to disconnect things right now. Get it running correctly first, or you may never figure out the problem until a rod punches through your block.

1) You need a new rotor, cap, coil, spark plugs, and plug wire set. You just do -- they have been sitting, and probably still have AMC printed on them. When you get the new parts, go for the TFI pieces, it's only a few dollars more. The Pford coils even work with your snap-connector, so no splicing!

2) Change all your fluids immediately. These include: Oil, water, transmission, transfer case, differentials. Dextron III and ATF +3 are both correct for the automatic transmission. Depending on your case it's either Dextron III or motor oil. Your differentials get 80w90 synthetic. (Don't skimp here, use the synthetic.) For the thermostat, nothing less than 190 degrees should be used on daily driven vehicles in order to minimize condensation buildup inside the engine and keep contaminants vaporized, allowing them to vent.

3) Replace your filters. Air, fuel, PCV valve and filter. (You should have gotten your Oil and Transmission filters already) Put a new radiator cap on -- but only after your sure your radiator hasn't dry-rotted out, or you'll be surprised. Change your thermostat.

4) Your vacuum lines are leaking. Replace them. You don't need the plastic emission line ends, use a short piece of hose to connect them, but do get the plastic line, it doesn't collapse or pinch as easily, resists heat better, and has a smaller volume for better response. Pick up some plastic or brass T's.

5) If you have problems with hesitation or hill climbing, you might have rust in your tank. This is especially true if it has been stored on a partial or low tank where moisture can get in. The only cure is to drain and drop the tank and blow out the lines. Sorry.

6) Your springs probably need replacing too, especially in the rear. A helper spring may work and is a good idea anyway if you plan on towing or lots of hauling, I have seen few cars that don't sag terribly when loaded full or with a trailer on them.

7) Replace those rust tubes where your shocks were. If there was any surface left on them, they would have AMC printed there! This is amazingly easy.

8) Intake and exhaust bolts work loose, and can cause poor performance. Check the bolts in your car and tighten things up.

9) Check your 4wd. (See the 4wd post)

10) While your in there, get new belts, top and bottom radiator hoses, and heater hoses. (3/4 & 5/8) There are several brands of "Insulated" hose, that might save you a layer of skin one day. 1/2 and 3/4 copper pipe from the Home Megastore can be used for hard line if you want to route tight turns.

First improvements

1) TFI or HEI upgrade. You probably did one of these as regular maintenance. There are several kits on the market that are complete HEI upgrades. They improve idle and benefit emissions. Despite the claims of the after-market ignition guys, unless you have a high-revving engine (over 5000 on a regular basis) you will notice little performance difference over the most basic points ignition properly tuned. Those benefit in slightly cleaner idle and rev-limiting.

2) A new carburetor. Let's face it:

A) Your carburetor is old, and in need of a cleaning and a rebuild.

B) Factory carburetors, especially in the emissions era, are undersized for the engine. While your BBD is probably great on a 4-cylinder engine, it doesn't cut it on a six, and tops out by 4000.

C) Carburetor technology has progressed. Modern designs (~1975+ depending on manufacturer) are much more advanced then older versions.

Now, our BBDs, both computer controlled and non fall within this category, and are indeed good choices for smaller cars. But keep this in mind when you look for replacements. Even newer designs are often able to pass smog tests without the computer.

3) Aluminum or Steel valve cover. If you don't plan any major upgrades, do this! Plastic valve covers were the major weakness of these engines. My 87 Aluminum cover has around a dozen bolts holding it down, showing AMC realized the problem and fixed it right. Eventually.

4) Roller timing chain. There is a Mopar double roller timing chain available. It runs better and is going to remove the slack from your valvetrain.

5) Tow-package Radiator. Nothing cools your car like a new, well-oversized radiator.

6) Intake manifold. This may be part of the carburetor upgrade anyway. Ours are known for being slightly restrictive, and it's a good place to end if you are keeping 258 heads.

7) Transmission cooler. Our transmissions work hard, give them a break, the fluid will last much longer.

Major upgrades

1) 4.0/242 High Output head. This is THE major upgrade. After ignition and a new carburetor, this is probably the biggest bang-for-the-buck upgrade you can do. It will instantly add 40-60HP. (4.0 is rated ~180 HP, ours 110-120) This is the major difference between a 258 and a 4.0. (the two others are cam selection and MPI.)

2) Multi Point Injection (MPI) or Throttle Body Injection (TBI). Both systems are available as kits, and consensus is there is about a 5-10 HP and ~1 mpg difference between them, with MPI on top. I would estimate TBI being that much again over a properly tuned modern carburetor, and much more over the stock BBD. Also, you get better idle (Again!), throttle response, top end, and much better cold engine performance. If you are going for a conventional rebuild with a stock cam and head, MPI is for you, but it's twice as much.

3) 700r4 Transmission. Yeah, the AX4 bolts right up, but it's computer controlled. This guy is compatible, has a .70 OD, and is cheap. Half the cost of an after market OD. Plus there's a really kickin' first gear in it. If you don't have the tow package, you should change your differential gears to at least 3.08 and maybe 3.31.

4) T5 Transmission. The other half of the overdrive, for you guys who like to shift, or have only four angry squirrels to move you. This is probably how you get 30 MPG in an Eagle.

Emissions

These are probably the least understood parts of the engine on an Eagle. Out of frustration, many people just rip the whole thing out. (And it still doesn't run right!) Furthermore, most of these things have little to no effect on power when running correctly.

1) Your Catalytic Converter. This is easily the most blamed part of the whole ensemble, and seldom the culprit. Sure, that old '80s cat is a little restrictive, but if there is big problem with your cat it is a symptom of something else!
A) Replace it with a modern, high-performance cat. We are pre-OBD, so any certified cat will work, but an air tube is preferred.
B) If your computer is deleted, the downstream tube should get manifold vacuum when the engine is hot, and the upstream should come on when the engine is cold. The upstream compensates for richness in the exhaust and the downstream provides oxygen for the second catalyst.
C) If your cat is clogged, your car is running too rich and needs tuned However they usually produce minimal back pressure, using just a few hp, and no noticeable difference at low RPM, where our Eagles usually run.

2) Exhaust Gas Recirculation EGR was introduced to reduce NOx emissions in the exhaust by reducing the combustion temperature. It displaces a small amount of the intake charge with inert exhaust. It does NOT bun unused exhaust gases as some people report. As a side benefit, it slightly reduces the engine's effective displacement at cruising speeds to increase efficiency and reduces knocking on lean conditions. It's effects are similar to water injection, but always available.

3) Ported vacuum distributer/distributer retard In order to reduce idle emissions, the distributer is retarded at idle to allow the engine to run slower with the throttle plate further open and a leaner mixture, since most idle mixtures are closer to 12:1 rather then the 14:1 optimum. This causes increased engine heat at idle and can cause a poorly performing cooling system to overheat.
In the 60's automakers found the solution to this problem -- a dual vacuum switch that goes from ported to manifold vacuum at ~220�. This is why so many of the cars of that era idle higher when they're hot. The ECM provides for partial retard at idle, so your distributer vacuum advance should be attached to manifold vacuum.

4) Positive Crankcase Ventilation PCV is the simplest, oldest, and most useful emissions device on the whole engine. If there is one device you should never disable on your car, this is it. A) It prevents hydrocarbons from blowby and oil from entering the passenger compartment. B) It drastically reduces sludge and varnish buildup in the engine by moving air through the engine. C) It keeps the engine under a slight vacuum that helps the gaskets to seal and keeps oil from leaking out of your engine. Positive pressure is the #1 reason for oil leaking past the gaskets. D) It keeps your 200,000 mile engine from leaving a blue cloud everywhere you go. It only malfunctions for three reasons: bad seals or missing plugs in the crankcase, bad or wrong sized PCV valve, clogged filter element. If you don't have a PCV valve location in your air filter pan, either drill a hole for it or make sure that a hose goes into your air cleaner behind the element. Race style breathers look cool, but just don't work as well as a completely closed PCV system.

5) Stepper motor/Oxygen sensor This alters your air/fuel mixture, keeping it near the 14.7:1 "Golden Ratio" which is good for your cat and good for your engine, as a compromise between power, economy, and knocking. It also provides the computer with data to work with other parts of the system.
As any backyard mechanic knows, richer (~13.5:1) creates more power (but washes the cylinder walls), and leaner (~17:1) is more economical with fewer emissions.

6) Air Injection Reactor (AIR) Injects air into the exhaust manifold just near the exhaust ports, causing continued burning of the exhaust. It cuts out on deceleration to prevent popping, and on WOT to reduce backpressure. It's prone to rust, leaking, overheating exhaust manifolds, and burning valves -- that said it usually works fine. The pump uses less the one horsepower on most engines, but is even more pipe-laden then pulse-air. If you dump it, put a simple 2-phase cat on your exhaust.

7) Evaporative system This includes your return-line fuel filter and the charcoal canister. However it works on your car (usually ported vacuum, possibly venturi) it usually just purges a little vapor into the carb at part throttle. It has a lot of hoses (3-4 on the canister alone) but it is pretty benign, until it breaks, and is universally looked for in inspection. Keep it.

8) Your Sol-vac Really just the long arm of the computer, it's a two-step solenoid -- off, low, high. Low is the electrical solenoid, which kicks in when the lights or defroster is on, or the A/C comes on. High is the vacuum part that comes on when the computer triggers the rightmost of the three valve cover vacuum solenoids. When your car starts, the computer holds it high, then low, then off over about a minute. If you remove the stock computer you can use this for many interesting purposes, including your A/C kickup, and an anti-dieseling solenoid. Just re-wire the connections on it and its vacuum solenoid.

9) Warm/Cold air intake & Air cleaner damper The warm/cold intake switch is usually piped both to your exhaust stove and to a fresh air pipe. Both hoses are usually gone, but the stove pipe warms your engine faster on those cold winter days, and the cold air hose gives you a denser air charge and more power, an old hotrod trick.
The damper completely closes off your air cleaner to prevent hydrocarbon escape as hot gasoline evaporates; it's on a delay valve only to keep it from slamming open when vacuum reaches it or closing fast on hard acceleration. If you bog off idle, just wire it open, it's fairly useless.

10) Manifold heater This is an oil-pressure controlled electric heating element in your intake. It replaced the exhaust stove, and is very nice when you start your car on those cold mornings. Since it is independent of everything else, it seldom has any problems, except when it's not connected. It keeps your intake above 160�. If it really bothers you, install a switch to cancel it, or unplug it for the summer. Once the water gets flowing through your intake, it's not really needed anyway.
People always feel the need to have the coldest intake, just like the drag racers have. Thats bunk! It only works with MPI, and does little good in that hot engine compartment strapped to the head and over an exhaust manifold. I suspect the water may even be cooling it.
Some heat is required in the winter to keep the gasoline and ice from condensing on the walls, since evaporation and vacuum reduce the temperature of the air. (I have had ice form on a carburetor. It's not fun.) Constant temperature equals constant performance, so if it is disabled, you may find your fuel economy all over the map.
Replace that cold air intake first, and get rid of that silly chrome air cleaner that's drawing in all that hot air right off the top of the engine. Hey, does that air cleaner still spin when the car stops?

The Four Wheel Drive System

Ah, yes. The heart of what makes and Eagle. That NP transfer case and the front differential that hangs from the engine on those two mystical bolt holes that AMC added in 1980.

1) If it hasn't caught your eye: YOUR OLD VACUUM HOSES ARE LEAKING. Check the hoses into the car and the connectors on your transfer case and front disconnect if you have them.

2) If your front disconnect motor still works, you have options. You can keep it in the system for the stop-and-shift. You can connect it up to another vacuum source that keeps it always engaged for the later selec-trac behavior. You can remove it and lock the fork in place with a hose clamp. You can replace the front axle. You can put a separate vacuum switch in to operate the transfer case independently of the lockout. If you do so, beware you can ruin your viscus coupling if you have it in 4wd and the axle in disconnect, because it freewheels in the front. You do, however, gain the 1 mpg that's claimed by the disconnect feature and still get shift on the fly if you have it engaged beforehand.

3) If your axle disconnect is broken, clamp it. All other options are expensive unless you just happen to have a parts car on hand for an axle swap or a spare motor.

4) If your transfer case is broken for any reason, you can use one from a Cherokee. They are viscus with an optional low-lock on a separate cam. Swap everything necessary over and fabricate a cable or lever, or even lock it in high. Your Eagle has the correct flat spot for mounting the lever on the floor, but it requires cutting.

5) The 1986 Mistake. A few cars have an open differential in the transfer case. If one wheel slips, they all do, just like any other open differential. The only real option is to replace it with a viscus center transfer case.

6)Limited Slip Rear. AMC never offered one on an Eagle, it has two wheels that will always receive power anyway, one front and one rear wheel will always be moving. However you can add a rear end from a Concord with limited-slip or pick up one of various after-market choices for the AMC. Generally, only remote lockers should be used in the front end due to interference with steering.

Fuel Delivery

If the oil pump is the heart of an engine, the carburetor is the lungs, liver, and pancreas. It has been said that a carburetor is an incredibly ingenious and complex device designed to provide exactly the wrong air/fuel ratio under all conditions of load and speed. Considering how people treat them and their early history, it can be hard to disagree.

More then any other section, there is room for disagreement here, but I hope I can dispel most of the myths of fuel delivery for you.

Basics

There are three divisions of fuel delivery for engines: 1) Wet manifold; 2) Dry manifold; 3) Direct injection. All have been applied to the gasoline engine, but of them, the first two are the most common, owing to gasoline and alcohol being semi-volatile.

Overview

Wet manifold covers Throttle Body Injection and Carburetion and differs in manifold design from dry manifold, or port injection. port injection is further divided into sequential and non-sequential. Sequential port injection times the injection event to the valve opening, other systems fire either in banks or all at once, providing a semi-wet manifold or pooling fuel on the valve.

By far the most finicky method is sequential port injection, as found in the Chrysler/Jeep system. Too much variation in engine design from expectations, and the engine will run poorly. Properly tuned, such a system can provide a small advantage in horsepower and economy over other systems, mainly through the evenness of the fuel delivery across the cylinders. (In the six, the end cylinders tend to run lean, while the middle run rich.) Sequential port also provides for a much simpler manifold since it doesn't have to keep fuel in suspension, and can be runner-tuned for narrow RPM gains much easier, as (strangely) seen in the Ram Air designs in Pontiac engines and early 301 Chevy TPI engines. (Interestingly, the TPI system is NOT tuned for any other engine. It made a bad engine good, but chokes larger engines.)

In terms of power gain and efficiency, the list is pretty obvious: sequential port, TBI, carburetion. The spread, properly tuned, is slim, official figures are under 5% HP between sequential port and TBI, and that includes several other engine modifications between them. I have seen no direct comparisons to carbureted engines, the factory engines have too many variables over too much time to allow any meaningful comparisons.

Carburation

There have been many advances over the years in carburetion, but one of the more significant is the vacuum-operated four barrel. Tuned properly, such a device can provide better drivability and fuel economy then any other carburetor.

There is this desire among automotive enthusiasts to become either drag racers or circle track racers, but we are operating neither one of those vehicles. A Holly Double-Pumper, on ANYTHING but a race car is like trying to attach a roof to a house with a sledge hammer. It will idle rough, have flat spots, gulp fuel like it's still 97� a gallon, and you will spend days tuning it to be that good. These are for radical camshafts or forced induction where there is no reliable manifold vacuum to determine load.

This brings to the front an important issue. The accelerator pump on a carb is not a desirable feature for designers. It's purpose is to cover the time between the opening of the butterflies and the response of the main metering system when the engine would run lean due to lack of fuel and fuel dropping out of suspension with the sudden drop in vacuum. The smaller the necessary pump, the more efficient the carburetor.

One way to make the carb more efficient is to reduce the bore size. This reduces the amount of air it can pass, so the development of two and four barrel versions. Another way to increase signal is to apply additional booster venturi around the main jets. Smaller bores also provide more responsiveness due to the stronger signal available to the main jets.

An engine can die completely if it cannot bring the main circuit up to speed fast enough, if it is at a low RPM or just not big enough. Vacuum-activated secondary systems moderate this by not allowing themselves to open until there is demand for the additional fuel and air and not opening further then the engine can demand even at wide open throttle. They also keep the engine out of low-vacuum power bleed conditions more often and do not contain secondary accelerator pumps.

Two of the better four barrel carburetors ever on the market were the ThermoQuad and the QuadraJet, with perhaps a lean toward the ThermoQuad. These two are what are referred to as spread-bore, where the primaries are spread to line up with the centers of the much larger secondaries. The small primaries provide for excellent responsiveness and economy, while the secondaries respond to engine demand with extra fuel and air. These are rated around 600-650 cfm. The way to apply these to AMC inline sixes is with a special spacer, however Edelbrock makes modern vacuum secondary carbs that fit square bore intakes, of these the Thunder AVS appears most applicable.

Important There is quite the religious war between Holly supporters and others. Holly does make an excellent product, and it's obvious from their success. There is a considerable market in parts for Holly carbs. It's just that the goal of many of their carbs (and builders) is WOT performance.

Most of the bad carburetor press comes from improper tuning, no carburetor is going to run correctly until it is tuned for your engine, and too often the wrong model is on an engine. Holly does make vacuum-secondary carbs (which often get hacked to death to be turned into poorly running mechanicals). For a time, they had power valve blowout problems.

Economy and part-throttle response is seldom the focus of review in performance magazines. The usual practice is to strap them to a dyno and measure peak ratings. Hollys can be tuned for good performance here, yet I have never seen a direct comparison on part throttle power or flat spots.

Weber

The Weber style carburetors. 32/36 DGEV and 38 DGES. The EV is directed at a more economical engine, and the ES at a performance engine. These would theoretically be very efficient carburetors, not having accelerator pumps. However, they are more sensitive to vacuum problems then others, and don't provide the big "seat of the pants" difference other carbs do.

Hesco MPFI

One of the weaknesses of this system appears to be the reliance on 14� of timing advance at idle. After looking at the Hesco site, I

H/O Head

Reported for a 40 hp gain and a 15%-18% economy gain. 4.0L Head Gasket New 1/2 inch Head Bolts You can use an exhaust manifold form a late 80's Jeep Cherokee with the Renix fuel injection. 258 intake manifold works. Valve Job Deck Valve springs should be matched with the cam, don't just get the strongest you can find, you'll wear out your valve-train faster and may end up rounding your cam before it breaks in. 1991 or newer #7120 Champion RC-9YC4 Plugs. Generally 1971-1980 and 1988-90 258/4.2L Engines have 1/2 inch Head Bolts. No changes required. 1981 through 1987 engines have 7/16" Head Bolts. Do not reuse your old head bolts.

1. Coat stud bolt #11 with Loctite 592 sealant or equivalent.
2. Tighten all bolts to 22 ft/lbs following sequence.
3. Tighten all bolts to 45 ft/lbs following sequence.
4. Recheck all bolts at 45 ft/lbs following sequence.
5. Tighten all bolts to 110 ft/lbs, except #11 at 100 ft/lbs.

12	8	4	1	5	9	13
----------------------------------------------------------
11	7	3	2	6	10	14

• Torque Rocker Arm Assemblies to 19 ft/lbs.
• Torque Spark Plugs to 27 ft/lbs
• Torque Valve Cover bolts to 70 in/lbs

• Torque the manifolds in the same type of spiral pattern and retorque your manifolds after about 500 miles of driving.

Year	Fuel/Computer	Features	Rating
->86	ECC, Carburetor	Base	5
87-90	Renix	bigger valves, better ports, seperate center exhaust	4
91-95	Renix?	"High Output" - higher ports	1
96-98	OBD II	Similar to 91-95, without the coolant temprature sending unit boss, smaller cam (piston redesign, main bearing girdle added)	2
99.5+	OBD II	smaller exhaust ports, bosses to mount coil packs (distributorless ignition) (poss. prone to cracking)	3

Wheels and Tires

• 195/75R15 26.5"
• 205/65R15 25.5"
• optional
• 215/65R15 26"

Jeep Cherokee 81-01 rims fit. Stock back-spacing is 4.5" (40 mm / 1.5" offset) and the stock rim is 6" wide on a 5 x 4.5 pattern.

Suspension

Control Arms

ID of 1 & 3/8 for washers to fill control arm brackets.

Springs

Jeep Cherokees (XJ) use the same springs in the back (in size at least, spring rate is probably different, but should be close). There are many companies that sell lift springs for Cherokees, so there is lots to choose from.

The front mount fits up perfectly with the existing bolt. Put a spacer on teh stocl lower shackle bolt to jump up to the larger XJ spring bolt size and your good to go. OK for model 30 cars, too long for 50's.

Body

Misc

s-10 bug shield

Engines

Stock

AMC/JEEP Iron Duke 151 4 cylinder

Manufactured by GM and used by AMC through 1983. When converting to a Chevy 90 degree V6 or V8, no adapter is necessary. You are limited to a 10-1/2" clutch assembly and a GM Mini High Torque starter.

AMC/JEEP 150 4 cylinder

This 4 cyl. engine has the same bolt pattern as the GM 60 degree V6 and is used in vehicles 1983 & newer.

4 Cylinder Differences

The GM 151 rear cross-member uses a mount that may bolt from the x-member directly to the t-case.
The AMC 150 rear cross-member has a plate that adapts the top of the transmission mount to the t-case.

part #'s for x-members are:
Front

• GM J3239263
• AMC J3242710

Rear

• AMC 89 32 000 762
• GM J3239340

Interchange

230 Chevy straight 6. GM 151 flywheel housing bolts up to the 230.

a big block chevy fuel pump block off plate works on Eagles

Transmission

150-T   3spd synchro    (258/304/360)           '74-'79
SR-4    4spd synchro    (232/258/304)           '76-'81
T4      4spd synchro    (151/258)               '82-'88
T5      5spd synchro    (151/258)               '83-'88
HR-1    4spd synchro    (121)                   '77-'79

HR-1 (by BW) was the tranny used by Porsche/Audi 121cid and it has an unique bolt pattern.

Lexus V-8 and Turbo Supra AW-4 trannys have a couple extra steel and fiber clutches (not sure of exact numbers) and a few other mods from the factory. The hard parts will interchange with the Jeep version.

You'll need the 3.54 gears -- the AW-4 torque converter only has 1.4:1 torque multiplication, not 2:1 or more like typical US built

a518 is basically the updated 727 - it has the OD unit stuck on the back. Same story with the 42/44/46 RE(electric shift) & RH(hydraulic shift).

Dana 35 gears will fit in an AMC 15 because it is a Dana 35.

The 30RH automatic came with the four-cylinder from 1992-1995. Automatics for the six-cylinder YJ were primarily the TF999, followed by its variant, the 32RH.

Miscalenous

72+ CJ sending unit. Adjust feed tube. 72 up CJ should work. You'll have to bend the angle of the pickup tube slightly otherwise it bottoms out. The resistance should be close to the same, Jeeps run between 10 ohms in the full position and 78 ohms empty.

1985 Ford F150 I-6 (300) plug wires

Rear defroster

You may be able to reattach them with electrically conductive epoxy. If not, here's some things to look for:

• The ground is on the passenger side, the hot lead on the driver's side.
• If you remove the trim that holds the headliner at the rear, you should be able to get to the connections.

Chevy V-8 2.5L/151 in� Jeep used the GM Iron Duke inline 4 1980-1983. These use a Chrysler Torqueflite 904 automatic transmission with a Chevrolet bellhousing

Metric/Small Corporate 1984-93 GM Iron Duke/Tech-4 RWD inline 4. GM Iron Duke FWD inline 4; Jeep/AMC 2.8L V6 (GM engine); 1984-03 Jeep/AMC/Chrysler 2.5L/150 in� I4 found in Jeep Cherokee, Wagoneer, Comanche, and Wrangler models (except Grand Wagoneer & Grand Cherokee) and 1996-2002 Dodge Dakotas.

Eagle 151 1981-1983; 150 - 1983.5 SX4; 1984-1985