We bought a 1990 extended cab short bed gas (318) truck for $1,400. Automatic transmission, air conditioning.  Nice little "farm" rig. We're going to paint it the old forest service green and spray in a bed liner. My wife is a forest service brat. Her dad was a ranger and smokey the bear. 

Awesome.  Was 1990 still carburetor?  

Yes, has carburetor. Thinking about stripping all the emissions stuff off down to and old school 318. Has an air pump. 

11 hours ago, joecool911 said:

Yes, has carburetor. Thinking about stripping all the emissions stuff off down to and old school 318. Has an air pump. 

 

I would.  Most of the old stuff probably doesnt work anymore and is just a big vacuum leak.  

You guys aware of any drastic problems these rigs have? I had a 1985 with the 360 and it went 280,000 miles before I sold it and I still see it running around. Only thing that I did was transmission rebuild. 727. Heads never even removed. 

 

I had a dodge boogie van that had the 318. Crazy good motor with ZIP. 

Well, aside from the "usual" items, not really.  It is a LA V-8.  I am more familiar with the older 70s stuff, but for the most part I don't think they changed much.  Below is a bunch of info.  I doubt you will encounter all these problems, but this is more general info.  most likely you will just have a slightly cranky old truck that wants a new rotor, cap, and eventually a fuel pump.  

 

The basic rules are air, spark, fuel.  If it spins it has air.  You can take a plug wire off and use a spare plug grounded against the frame or block to look for spark.  Fuel, is slightly more complicated but generally if it has fuel it will run, even if dribbled down the carb.  Though it will run poorly if the carb isn't happy.

 

Vacuum leaks.  track them down, replace or plug the lines that leak.  A vacuum gauge can be a helpful tuning tool, but definitely isn't required. 

 

Charging system is old school mopar voltage regulator.  Pretty fool proof, theres a regulator, a wire, and an alternator.  If they work, they work.  

 

Starting system.  Old school mopar planetary starter.  I still have the original 1969 one from my barracuda, and it works.  These can be rebuilt and will likely outlast the car. The relay to start it should be on the fender.  It is a standard 3 prong, you can turn it over with a gator clipped starter switch or a screwdriver to jump the right terminals. 

 

Ignition system.  You may have some sort of weird lean burn setup.  I don't know much about those.  However, it should have a mopar electronic ignition box on the firewall, and aside from a cap and rotor once in a while it shouldn't give you too much trouble.  I would check the timing and set to factory.  If you have problems with the distributor or if the emissions stuff is too much of a pain or makes it advance too much, I would just go get a drop in complete replacement mopar small block vac advance distributor and replace the whole thing.  But, I bet it will run just fine as is.  Also, look over the wires and look for burns or cracks.  If there is a big ceramic thing on the firewall with a wire going from each end, that is a ballast resistor.  I like to carry a spare one.  

 

Lights.  Most of your running lights are likely grounded through the body.  If they don't work with new bulbs, look at the sockets where they clip into the body, likely its all corroded or may need a new ground strap from the bed to the frame. 

 

Cooling system.  You should have a copper radiator, or a very early aluminum.  shouldn't have any problems as long as the owner did 2 year coolant changes.  If not, you can try the flush, but eventually you might end up replacing it.  Do the water pump at the same time.  

 

Fuel system.  If the truck has sat for a while, I would just go ahead and replace the fuel pump.  They generally go bad if they don't get used.  i would also replace the fuel filters with clear ones.  I just went on Amazon and ordered a couple FRAM G2 filters, they are old school clear plastic and are nice for troubleshooting. The ethanol in gas can really clean an old fuel system, dredging up gunk that will clog filters, bowls, jets, etc.  Once this is all done though, it should be ok, but I wouldn't leave it to sit with an empty or half empty tank as the ethanol will absorb moisture from the empty space in the tank and really make it rust.  The old school gas didn't have this problem. 

 

Emissions system (gas vapors) There should be some sort of a weird can somewhere in the engine compartment full of charcoal and a ton of vacuum lines running to and fro from your gas tank.  I hate these things.  They are mostly inoperative now and no parts are available to rebuild them, so I like to plug them.  If you don't have this system, great!  There may also be a can that is used as a vacuum reservoir, if you have this, I don't know what to tell you.  My dart, charger, and barracuda didn't have that.  

 

Trans, yeah it should be a 727 of some type, mabe a 904 (light duty 727).  It may have lockup on this new of a model, if so, great, hopefully it works.  A band adjustment is probably in order.  

 

I don't know much about the Tcase. 

 

If the carb gives you fits, and it is a factory 2 barrel, you may end up needing to put a new manifold to put ezefi or a new edelbrock carb on it if you can't find a carb shop or rebuilt 2bbl carb.  You will also find that the kickdown linkage will be important here if you do a swap.  The kickdown is very important and the linkage isn't very adaptable to non factory mods.  Lokar makes a cable kickdown setup that is decent.  

 

Choke.  If it has an electric choke or a thermostatically controlld choke (rod sticking up out of the manifold to the choke lever on the carb) it may not work right.  You can make it manual or remove it.  Just be aware of whatever it is as it will effect cold starts.  

 

The engine should be fairly basic.  Over time, it will leak oil.  The valve seats were induction hardened at the factory.  Over time the valves will recess into the heads a bit.  This has nothing to do with leaded gas.  It has to do with high cylinder head temps and miles.  Leaded gas increased the octane of fuel, it never "lubricated" the valves.  I would run diesel oil or amsoil Z-rod in the engine to keep the anti wear additives up for the flat tappet cam.  If you don't, you run the risk of wiping a cam lobe and needing to replace the cam and all lifters.  You have a pretty darn good motor all in all.  There isn't much there to break.  

 

Look at the exhaust manifolds for any type of flapper valve, if you do, it is probably stuck.  Hopefully it is stuck open. Some of these engines had thermostat controlled butterflys to close the exhaust to get the engine warmed up faster.  

 

PCV valve, replace it if it doesn't rattle when you shake it.  Should be sticking out of the right hand valve cover and feeding into the intake.  

 

Another note on vacuum... not all vacuum ports are equal.  Some are directly into the manifold, some are ported depending on throttle position or have a smaller orifice.  When in doubt for troubleshooting, refer to manual if possible, or plug it.  You want your brake booster going to the full time vacuum, haha.

 

Theres my brain dump.  You probably know a lot about it, but hopefully this helps. 

 

Lastly, parts for these old vehicles are generally really cheap!  I look at Rock Auto, get the part numbers, then compare on Amazon, NAPA, etc.  As many of the parts aren't selling fast, they have some killer cheap deals sometimes.  

Edited February 10, 20178 yr by CSM