Multiple questions from a new SX/4 Owner

[idahosx4]

Recent owner of a 1981 AMC Eagle SX/4 with a 258 here. It's the same eagle originally sold by forum member JSK to a guy in Oregon who I bought it from. It's doing well. It now has a GRONK motorcraft installed, along with air injection, egr, and charcoal canister removed. It's starting up great and runs mostly well. I plan to fully restore this beast over the next couple of years.

So below are questions concerning three of the issues I'm working on now.

First is the PCV setup. I just got it back from a shop who I had hook up all the vacuum lines correctly and tune the motorcraft carb. It runs very well now and starts up perfect, but is leaking oil from the valve cover and is spewing crankcase vapor everywhere. The shop said I have excessive blow-by. The PCV valve is hooked up correctly, but the rear port on the valve cover that should be connected to the intake through a breather was plugged. I suspect my PCV valve could be clogged or just not enough for the amount of blow-by on a worn engine, causing positive pressure to build up in the crankcase and  probably blow my valve cover gasket. My question is this: If it turns out the rings are worn bad (I'll be testing compression in a couple of days, have to buy a gauge first), and the PCV valve isn't enough to handle the extra vapor, what are my best options? I read one post that said just removing the valve and applying manifold vacuum directly to the valve cover, with a check valve on the other end, is a good route?

Second is my speedo gear. The second owner, (JSK), swapped out the differentials from a 4 cylinder to get the 3.54 gears. I tried to swap the right size speedo gear in, because it seemed so easy. But now my speedo doesn't work at all, and I suspect the gear is shredded (will find out this week when I pull it out again). Is there a good guide on how to do this? There were numbers stamped onto the outside of the piece you pull from the transfer case, which I assumed were number of teeth, and so I lined up the arrow with the right number.

Third is my transmission. I have the SR4 (ugh). I have a lot of problems changing gears, where the shifter gets stuck or won't go into gear unless I pump the clutch a few times. Also, if I put it in reverse, it will still transfer power with the clutch pedal all the way in, and so when I let off the gas it kills the engine. I then have to pump the clutch to get the shifter unstuck. This sounds like I need a new master cylinder? Any reason why it wouldn't be that? If it is, where is the best place to get a new one?

Thanks guys!

[carnuck]

first. There is a solenoid in the line for the PCV. Throw it away and use a new hose. Put the breather hose into a can (if plugged, the line will force oil out and eventually break the rear seal or blow out a gasket) then to the air cleaner or the filter will get soaked in no time.

second: There is an alignment notch that meshes with the number of teeth on the speedo gear. If you didn't match it, it may not be touching (or the speedo cable died)

third: If you aren't losing fluid, then yes, the master needs replaced.

[captspillane]

You should look at the connection point on your clutch pedal. That U shaped bracket is known to fatigue and bend, which causes the clutch pedal to reach the floor before the linkage can go back far enough to actually release the clutch. Two of mine came to me with complaints of poor shifting and I found them bent back several inches like that.

If you need to pump to get pressure, you should first replace the slave cylinder. Those usually go more often than master cylinders. When your master cylinder goes bad it will usually lock up, which will destroy the U-shaped bracket the first time you go to push it down. I've seen quite a few pedal assemblies that have already been welded and reinforced because of prior damage.

You likely have the horrible tube style upper fluid resevoir, another big reason you might be starving for fluid. Those have all been dry-rotted and cracked and leaking in my eagles. They also hold a pathetic amount of fluid, so they need to be constantly checked and refilled to keep from getting stranded and unable to shift. A simple fix is to replace the old tube with a new longer piece that is easier to get to. The best solution is to install the great clutch resevoir used in all the Iron Dukes and a lucky few early '81 258 Eagles.

[idahosx4]

Thanks for the help guys.

It looks like my slave cylinder is definitely bad. I tried to drive it this morning and had to pump the clutch a lot, and it wouldn't stay disengaged when I held the pedal down. I took a look underneath and watched the slave cylinder while the pedal was pushed in, and sure enough it's not holding pressure. The U-shaped bracket you mention looks fine on my pedal, so I'm sure it's going all the way, it's just not holding pressure. My reservoir has remained full (looks like I have the nicer reservoir? I'm not sure what the bad one looks like in comparison), and it's hard to tell if the slave is leaking because I have a lot of oil and grime built up. Could the line be plugged somewhere? I've ordered a new slave and master just in case.

How much of a pain is it to unbolt the brake master cylinder to get to the clutch cylinder for replacement? The slave cylinder looks easy to replace but not so sure about the master.

Here's a teaser pic:

[idahosx4]

Also, can someone recommend a place to find the speedometer gear? I purchased the first one I needed from kennedy american, but it looks like they're out. I need the one from the four cylinder to match the 3.54 gears, which is red and I think 36(?) teeth. I'm also looking for a fuel gauge sending unit and can't seem to find that anywhere ...

[eagleman]

Are you talking about removing just the brake master cylinder or the hyd booster itself? If just the brake master cylinder its rather easy. A couple of bolts,a couple of brake lines and its ready to remove. The booster is a whole nother story. It can be done but not without a struggle and some choise words here and there.

[captspillane]

The Eagle speedometer irks me greatly. If you need to replace it I suggest fully replacing it with a better unit. The Eagle style adaptor assembly is interchangeable with the newer ones you would find in an '80s or early '90s Jeep of any model.

Essentially you end up buying a brand new speedometer cable for a J10 truck or CJ7 for about $20. That cable will have small 5/8" threads at the speedometer end just like the Eagle cable has. It will have large 7/8" threads at the other end that thread on to the round adaptor at the transfer case which has 7/8" male threads on it. If you find a 1992 Jeep Cherokee with manual transmission it should have the correct gear already (taller 3.07 gears but larger tire size) and until 1993 they had the electronic reader bolted to the outside of the exact same adaptor your new CJ7 speedometer cable will bolt to. Those should be easy to find and cost nearly nothing.

Once you change cables you will no longer need to remove the adaptor to pull the transfer case. That saves dumping the fluid every time and also saves the risk of eating up another gear, besides saving a great deal of time and aggravation. The XJ gears are also much cheaper and readily available than the old Eagle ones.

If you go Fuel Injection later you will have to do this step anyways. Both the MPI and the TBI speed sensor go between the adaptor and the cable down by the transfer case.

[carnuck]

The Eagle speedometer irks me greatly. If you need to replace it I suggest fully replacing it with a better unit. The Eagle style adaptor assembly is interchangeable with the newer ones you would find in an '80s or early '90s Jeep of any model.

Essentially you end up buying a brand new speedometer cable for a J10 truck or CJ7 for about $20. That cable will have small 5/8" threads at the speedometer end just like the Eagle cable has. It will have large 7/8" threads at the other end that thread on to the round adaptor at the transfer case which has 7/8" male threads on it. If you find a 1992 Jeep Cherokee with manual transmission it should have the correct gear already (taller 3.07 gears but larger tire size) and until 1993 they had the electronic reader bolted to the outside of the exact same adaptor your new CJ7 speedometer cable will bolt to. Those should be easy to find and cost nearly nothing.

Once you change cables you will no longer need to remove the adaptor to pull the transfer case. That saves dumping the fluid every time and also saves the risk of eating up another gear, besides saving a great deal of time and aggravation. The XJ gears are also much cheaper and readily available than the old Eagle ones.

If you go Fuel Injection later you will have to do this step anyways. Both the MPI and the TBI speed sensor go between the adaptor and the cable down by the transfer case.

I don't know if the gear will work, but the speedometer cable went away in '92 and they went to an electronic driven speedometer system.

[Prafeston]

I almost bought that car from JSK when it was in St. Louis. I remember it needed some things. Floors and the rain rail repaired on the passenger side. Other that it seemed like a great car and the Motorcraft carb should solve some issues. Look forward to seeing this thing get finished!

[captspillane]

I don't know if the gear will work, but the speedometer cable went away in '92 and they went to an electronic driven speedometer system.

The new 1993 and up "Short gears" are different than the 1992 and older "long gears" which are also different than the Eagle gears.

Yes, it will work. I have it installed in my Eagles already. The 1992 and older Vehicle Speed Sensors attach to a mechanical adaptor piece that will also work for a 7/8" thread mechanical speedometer cable. In 1993 they went to a one piece plastic VSS that is useless to us. The picture shows the VSS seperate from the adaptor I'm talking about. That adaptor was used in Jeep Dana300s, J10 trucks, Dodge trucks, and just about every new process transfer case 80's and early '90s.

[captspillane]

For my Green Eagle wagon I looked up the formula to calculate exactly what speedometer gear I needed. I selected a thirty tooth gear and it is not a noticeable difference from the ideal number. Use this formula to make sure you are ordering the closest gear before you go and buy one.

G=(20168xDxC)/(KxT)=(20168x3.07x13)/(1000x27.11)=29.69 desired teeth on speedometer gear

D=Differential Gear Ratio=3.07
C=Number of teeth inside the Transfer Case=13 for all the new process cases
K=1000=The Revolutions per Mile of the Speedometer, which is always 1000 for Eagles
T=Tire diameter in decimal inches

T=28.88 for 235/75R15 tires
T=27.70 for 215/75R15 tires
T=27.11 for 205/75R15 tires
T=26.52 for 195/75R15 tires (stock size for most AMC Eagles)

[idahosx4]

The FSM says you have to remove the brake cylinder and booster to get to the clutch master cylinder for replacement. Maybe someone who's replaced their master cylinder can say something? Do you actually have to remove the brake booster and cylinder? To me I can barely even see the clutch master cylinder because it's directly underneath the brake booster. Maybe I'll just start with the slave since that definitely seems to be the culprit. I ordered both and should be delivered end of this week.

I drained the transfer case again today and my speedo gear was actually not shredded, it only had one damaged tooth which I was able to bend back to the right position. When I put proper light underneath and looked at the gear, it was super obvious it needed to be in the 3 o'clock position, instead of the 9 o'clock the arrows suggest. Using that formula with my stock tire size and 3.54 gears says I need a 35 tooth gear which is just one tooth less than the 36 tooth gear I bought (the stock gear for the 4 cylinder). The first time I lined up the arrows associated with 36 teeth to the little dot on the transfer case but that was clearly wrong. Here's a pic of the position now:



I tested compression with the engine cold and I'm getting about 120 psi after 2-3 turns of the starter for each cylinder, which is on the low end of the spec but still not awful right? Maybe adjusting the valves will help with the blow-by. Once I get the clutch fixed I'm going to take it to a car wash and (unless enough of you tell me this is a bad idea) use some gunk remover and power wash all the grime and oil away so I can actually  find leaks.

Also, can someone point me to a breather for the valve cover that fits the 258? Local auto parts store only seem to have the huge ones for larger engines.

And Prafeston, yes, it needs new floorboards and exhaust very badly which are both rusted to almost nothing. But the rest of the interior is practically flawless and I'm almost convinced it has an original 64K miles, at least that's what JSK tells me. Also it has the louvers which are sexy as heck, though they need restoration. Before I bought this I knew very little about working on cars but I've learned a lot already and I plan to restore this as much as possible over the next year or two. Maybe in a year I'll strip everything off and pay for a proper paint job, who knows.