Older Chevy 4X4s: The Ideal EMP-Proof Survival Vehicles, by Vlad

Saturday, Jul 14, 2007

The ideal survival vehicle is a 4x4, 3/4 ton made by GMC or Chevrolet. They are easy to work on, old enough to be cheap, new enough to get parts for and, tough enough to last.
My 1976 GMC 4x4 3/4 ton pickup has 300,000+ plus miles. Maintenance = reliability. It has V8 350, 4 speed standard shift, 4.10 axles, dual-range transfer case, manual hubs. In Low range first gear I have crept up and down icy mountain roads with perfect confidence --- and V-bar chains on all four wheels.
Between the steel line from the gas tank, and the mechanical fuel pump, I installed a piece of new neoprene gas hose with two in-line fuel filters in tandem. This serves to capture grit that would abrade, and shorten the service life of, the fuel pump diaphragm; and otherwise clog the moving parts inside the fuel pump. Between the output side of the mechanical fuel pump and the intake of the carburetor I installed a long piece of neoprene gas line, with one inline fuel filter, secured where it will not touch the exhaust manifold.
At the front of the block, near the mechanical fuel pump, there is a hole threaded 3/8x16. Screw a 3/8x16 bolt in that hole to secure the fuel pump push rod. Remove the old fuel pump. Now is the best time to install neoprene lines and in-line fuel filters as described above. Install new fuel pump. Remove 3.8x16 bolt before you start the engine.
I swapped the high energy ignition (HEI) with a [microprocessor] electronic module) for a [traditional and EMP-proof ] points-type distributor. The HEI distributor is $200 and points-type distributor is $50. I replaced Quadra-Jet 4 barrel carburetor with an Edelbrock 1405 4 bbl carb, and bought a calibration kit. I can change jets and rods for anything from max power in axle-deep mud to economy cruise at high altitude. Just now I have it calibrated for 6,000 foot elevation. In East Texas 400 foot elevation at 65 mph I average 12.5 mpg.
My carb flooded. The engine would not start. I disassembled the carb on my tailgate and found a defective float. I replaced both floats (from my tool box), reassembled the carb and drove home.
In my truck toolbox I carry at all times a starter, alternator, fuel pump, complete distributor; extra points, condenser and rotor; and hand tools ...as well as food, a rifle or two, two axes, and a daypack with a few goodies. If you ain't got it with you it could be a long walk to get it.
I use the alternator but have a generator; and installed a wire-wound voltage regulator. The generator stays in my toolbox. It takes only minutes to bolt the generator in place.
Chevrolet part number 3814970, right exhaust manifold, has a place to mount the generator. It fits all Chevy/GMC small block V8 '73 thru '86. You can order a new one from your dealer.
A generator-equipped vehicle with standard transmission will roll-start without a starter or a battery. If the battery is missing, secure the positive battery cable clamp where it cannot possibly ground. Tape it to a heater hose. Roll start and go!
An alternator must be electrically energized to produce electric current. If your truck has an alternator you must have a battery.
Avoid automatic transmissions. Since around 1960 [US built] automatic transmission vehicles will not push start.
We can thank Big Brother for the many changes in automotive design. Electromagnetic pulse (EMP) from a nuclear detonation 400 miles above earth will destroy all unshielded electronic parts in line-of-sight. ...... the electronic components in Electronic-Fuel Injection, alternators, telephones, radios, televisions, computers, watches, GPS........etc
In 1945 we nuked Hiroshima and Nagasaki. At that time all vehicles had carburetors, generators with wire-wound voltage regulators, and points-type ignition. Vehicle exposed to EMP were still operable. In the early 1950s US conducted nuclear tests in Nevada, and studied effects of nuclear weapons ([including] EMP). Shortly thereafter the generator was replaced with an alternator that has unshielded electronic "chips" ..
If your racy 2007 model Technodazzle stops, call the AAA. Have it towed to the dealer. A highly educated Automotive Diagnostic Technician will attach it to a $100,000 computer to learn which parts to change. Repairs may cost as little as four months pay.
1973 through 1986 Chevy/GMC 4x4 pickup, Blazer and Suburban (seats nine if you wish) have 95% parts interchange. The same carb, fuel pump, alternator, starter fits them all. Every junkyard from Fairbanks to Florida has lots of old Chevy 4x4s.

Procedure for Changing HEI to Traditional Points Ignition on a 1976 GMC/Chevy V8 350:
A picture is worth a 1000 words. At the public library find a Chilton manual for 1974 Chevy/GMC V8 350 and study the engine ignition wiring; and photocopy those pages to use as a guide.
If possible, find someone who drives a 74 or older GMC V8 350 and eyeball his wiring.
buy these parts
- rebuilt points distributor for 1974 GMC V8 350, with cap and rotor
- also buy replacement points, rotor and condenser (for later tune up. each time you use tune up parts, immediately buy replacements for your toolbox for next time.)
- buy the Allen wrench with long handle with which to adjust the points
- set of points-type spark plug wires
- 8 each AC-Delco # 44 spark plugs (Gap them to 0.035")
- two ballast resistors ( one goes in toolbox for later)
- one coil and coil bracket (you may want to buy an extra coil at this time)
STEP ONE is to read all instructions three times before you do anything else. If possible have an experienced friend oversee your installation.
Begin:
-remove negative battery cable clamp from the alternator bracket.
-tape the negative battery cable to a heater hose (so it cannot ground).
-mount ballast resistor on the firewall.
-mount the coil and bracket on the fire wall below the ballast resistor.
-the (only ) RED wire that presently runs from ignition switch through firewall to your HEI distributor will be connected to the driver side of the ballast resistor. (cut the red wire at a point 3" from HEI distributor. cut a 15" inch piece of number 12 insulated wire to extend the RED wire to connect to driver side of ballast resistor.
use a butt connector to connect 15" wire to red wire. use a spade connector to connect it to ballast resistor.)
-with an 8" piece of number 12 insulated wire, spade connector on each end, connect passenger side of the ballast resistor to the "plus" ( + ) side of the coil.
-the only black wire hanging out the bottom of the points distributor connects to the
minus ( - ) side of the coil. (it goes from points to minus side of the coil)
For future reference, with a white paint stick, mark a large - and + on the coil. when you are cold, tired and the wind is blowing up your jacket (and your wife is asking if you got it fixed yet) it will help to see those marks and not have to rely on memory.
points distributor cap terminals --
#2 is the first terminal CW of the "door" in the distributor cap where you adjust the points.
firing order is 1 - 8 - 4 -3 - 6- 5- 7 - 2
with masking tape label points distributor cap terminals, HEI distributor terminals, and each HEI spark plug wire near the spark plug.
driver side front to back 1, 3, 5, 7 ..... and passenger side front to back 2, 4, 6, 8;
pull the plug wires off each spark plug but leave them connected to distributor cap.
remove HEI distributor cap with spark plug wires still attached. lay that aside for now.
Note the position of HEI distributor rotor. If it points to 6 o'clock, write on a 3x5 card "rotor to 6 o'clock" and tape that card on inner fender.
-loosen hold-down bolt ( 9/16" wrench) and remove HEI distributor
-install points distributor with rotor pointing to 6 o'clock (if that is what you wrote on the 3x5 card taped to the inner fender). the points distributor rotor must point exactly as did the HEI distributor rotor.
-hand tighten the hold-down bolt. later you will need to turn the distributor by hand when setting the timing.
you bought new AC 44 plugs and gapped them 0.035".
-now install the new spark plugs.
-install the points distributor cap.
-install the new plug wires one at a time. using the HEI distributor cap and wires as a guide.
-connect dwell tachometer black clip to ground, red clip to "minus" side of coil
-open the window in the distributor cap, and stick the allen wrench (with long handle) in the points adjust knob.
-connect battery ground cable to alternator bracket.
-remove vacuum hose from distributor, and plug that end of the hose
-with starter turning engine, turn allen wrench to adjust points so dwell reads 30.(book specs 29 to 31)
to set timing:
- with engine idling.
- the vacuum advance hose is still plugged.
- turn distributor CCW to attain maximum idle RPM, then CW to 200 RPM less than maximum
unplug vacuum advance hose. connect unplugged hose to vacuum advance on distributor.
with 9/16" wrench tighten distributor hold-down bolt.
if engine pings or rattles on acceleration:
-- disconnect and plug vacuum advance hose
-- connect dwell tachometer, black to ground , red to minus side of coil
-- loosen hold-down bolt and turn distributor CCW to max idle RPM, then CW to 300 RPM less than max idle RPM.
--tighten hold-down bolt to secure distributor
-- unplug and reconnect vacuum advance hose to distributor

Now let me tell you how we changed points in the shop:
-Since the engine will start if the points gap (which governs dwell angle, the number degrees of distributor rotation that the points remain closed) is close to .024", we'd install the point set and eyeball the gap to that.
-You can use a matchbook cover if yer eye is out of calibration.
-Then we'd crank it up and slowly turn the adjustment to the point where the engine began to stumble, then back the other way til it began to ping. The correct dwell would be -- within limits -- at the midpoint between the two.
-Timing can be done the same way mentioned previously but listening for the "ping and stumble" and setting midpoint between.
-When doing timing or dwell by this method, make the adjustment as smoothly as possible to make changes in engine sound more easily detectable. Keeping the distributor clamp screw just finger snug will make this easier when doing the timing.
-I toss this on the pile because there will be times when ya just do no have a dwell [meter/]tachometer in your pocket and have to change out ignition components that require adjustment. Get in tune with the pitch and sound of a properly tuned engine running at idle.
When I was doing this stuff regularly in my shop (I once was an automotive masochistic), I could by ear tell engine speed within 50 RPM -- no BS on this. If you are serious about this stuff, get intimate with your vehicle.


Packing '73-'86 GMC/Chevy 3/4 ton 4x4 front wheel bearings:
As always read instructions three times before you do anything else. You will need a metal pie plate and large magnet
- place magnet in center of pie plate.
- place small parts on magnet. (they will be there when you look for them)
special 3/8" drive socket for castellated nut inside hub
3/8" allen wrench
3/8" drive breaker bar
3/8 x 16 x 3" bolt
-wheel bearing grease
-spindle grease seal
-hub grease seals
-- chock rear wheel front and back
-- loosen front wheel lug nuts
-- raise front of truck on jack
-- place stands under axle housing
-- remove front wheel
-- with 3/8 allen wrench remove bolts that secure brake caliper
( place bolts on magnet in pie plate)
-- remove brake caliper and secure it without stretching or kinking brake hose
-- remove hub
-- with snap ring pliers remove snap ring
-- with special socket remove outer castellated nut
-- remove the washer (++ note that it has a pin that fits into a hole in the inner castellated nut)
-- remove inner castellated nut
-- remove rotor
-- remove the six nuts that secure the spindle
-- remove the spindle. it may be necessary to tap spindle with a brass hammer to remove it . do not use a steel hammer as that will mar the spindle-remove oil seal on inner side of rotor
-remove inner wheel bearing. wash it in solvent. dry it. apply new grease. put a golf ball size lump of grease in the palm of your left hand. place new bearing on the lump of grease. place right hand over left. squeeze hands together to force grease into the new bearing.
-place greased new bearing in the inner side of rotor. place new oil seal. with a brass hammer, or wooden handle very gently tap around the seal seating it.
-remove oil seal from spindle. remove old spindle bearing. grease and install new spindle bearing, install new spindle seal. A note on reassembly: Screw the 3/8x16x3" bolt into the threaded hole in the end of the axle. pull outward on the axle so you can get the snap ring on.
PS: Buy new wheel bearings and spindle bearings and seals to keep in reserve. Open each package. Grease the new bearings. Wrap them and put them back in the package. This will serve to keep them from rusting; and allow you to install greased bearings in the field. Keep the new bearings and seals in the toolbox on your truck.


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