Forward Lighting Systems    Harvey & Barracuda, May '67 SCG

    It was a dark and stormy night...we were trying to stay on the twisty Sawmill Parkway in rush hour traffic. The four weak headlights on our then 25 year old Plymouth Belvedere were not doing a thing on the glistening slick pavement.  I thought, boy, there has to be something wrong here.  I've learned the answer is yes and no. 

When I got my '67 Barracuda on the road I started to meet rallyists at the local SCCA club.  These are people who have to have good light!  A little later than sooner my Barracuda got 'H4' headlights and then a relay system.  Newer vehicles aren't always better although the trend finally seems to be moving in the right direction.    When I got my '85 Jeep Grand Wagoneer, I couldn't believe how weak the headlights seemed.  While it didn't as desperately need the relay system, I installed good H4s almost immediately.

For anyone thinking about upgrades the basic issues and solutions are the same:
1. Provide adequate power to maximize the performance of the lights. 
2. Use lamps that put the most light on the road with the least upward reflection. 

Headlight Types

    Sealed Beams:
Lens, reflector and lighting filament all combined in a vacuum sealed unit.  Works like an incadescent light bulb.  Replace when burned out.
- From the 1960s through the 1970s, all US manufactured vehicles were using sealed beams.

    Halogen Sealed Beams:
Same as above but slightly brighter  because they are more efficient.  Totally interchangeable with equivalent sealed beam.
  -A concours restoration vehicle would not want them because they are marked differently.  Other than that, they are more than worth the slight additional cost.
  - In recent years some have been hyped (that is marketed with unsupported claims)  but there are some that seem to be verified as better than others.
    Bulb Powered Lamps:
Lamp consisting of lens and reflector assembly that uses a replaceble bulb, usually an 'H4' or variant for the high/low beam. 
      - These came into use in the 1960s (but not in North America) with UK approving the H4 for street legal use in 1969 and Europe in 1972. 
      - They are often referred to as 'E-code' lamps as most were designed for European standards are so marked.
      - Over the years there have been some versions that also met and were tested and approved for US standards.   Now it seems most states will accept either.
       - Generally they focus more light down on the road and have a strong cutoff to reduce upward glaring light.

 Power (Wattage)

 Most of the standard low beam/high beam lamps are rated around 55 Watts/60 Watts. 
    Power rating is the power each lamp should draw and does not directly indicate lighting power.
    For the same 55 Watts, the halogen lamp will produce more light (see Lamp Efficiency below).
    Similarly a good H4 bulb in a good lamp assembly will put more light on the road for the same power as a sealed halogen.   They are also available in high wattage ratings.
     All lamps will be brighter if they receive full voltage.  However, an H4 bulbs whose voltage drops below a certain threshold will noticibly dim.

Headlight Systems

For the 1960s into the 1980s most European and American market automobiles used headlights of standard sizes. 
In terms of size and shape there are two arrangements using round faced lamps, and two arrangements using rectangular lamps.

Lamp Arrangements

System Efficiency

    The electrical circuits on many older American cars weren't redesigned as more 'accessories' such as wipers and heater fans were added.   Perhaps to save money or weight, Chrysler wiring was engineered their A+bodies with the minimum wire sizes needed to carry the required current.  The wires to the headlights are only 18 gage.  That's barely adequate to carry the 10 amps that two 55/60 Watt lamps can draw.  For safety, they have a 15 amp (instead of a 20 amp) circuit breaker in the headlight switch.    Even with 16 gage wire and 20 amp circuit breaker, the headlight circuit of any older vehicle where oxidation, vibration, heat  and other wear has deteriorated the wiring can cause problems.  Additional resistance is most likely to be found in the connectors and grounds. 
          Resistance does two things.  First it causes a voltage drop.  Lower voltage makes the lights dimmer.  Second it draws additional current into the circuit.   Current passing through an area of high resistance  produces heat..  Watts = Volts x amps.    While the circuit breaker may trip if the current draw is high enough (either 15 or 20 amps) it doesn't take too many watts to melt a plastic connector!   That can happen below the circuit breaker's rating.  I've had both happen with a-bodies....

Relays, a short path for a hot circuit.

Relays are remote switches.  Send them power and they turn a switch; Turn the power off, and they turn the switch off.
So, in a relay system power from the high/low beam switch is used to turn on the high or low beam relay.  The advantage is that a relay only needs a little current to be switched on.  Barely adequate wiring becomes overkill.  The real power for the headlights is fed to the relays directly from the alternator (or battery) using as heavy of a wire as required AND a circuit breaker or fuse.

Therfore, if in doubt of the wiring condition and not a concours restoration, install a relay system.  For those prefering a period correct look the system can be designed so the relays are hidden from the casual observer.    Alternatively, often there are kits and even pre-made harnesses for specific vehicles.  

Headlight Choices, or how not to get burned

Seems to be difficult identifying factual differences in headlights.  Lots of marketing hype;  Not much available hard data to the public;  Some experts unwilling to acknowledge a degree of subjectivety in personal preferences.    Remember, its your vehicle and its unlikely any of these sales people or experts have driven in your exact terrain, or have the exact same personal preferences.   However there are some scientific and semi-scientific independent tests,  and a number of real lighting experts (professionals in their field) that post on Candlepower forums.

The LED Alternative:
LED headlights have reached a point of development that some are a real alternative.  Lamps that are legit have met minimum US DOT standards and are so marked.
A big advantage of LEDs is the low current draw.   If you like your old vehicle of its classic look, LEDs are probably not for you.   This is because all of the LEDs point forward and can't look like a traditional lamp where the light is directed in part by the reflector. The light on the road is matter of personal preference here as all legit lamps produce a legal pattern when aimed correctly. 

Halogen Sealed Beams:
Some people are quite satisfied with these.  They are sealed from the elements and last a reasonably long time.  I have not personally bought any in years, but swapped the last set into my NPS work truck.  The GE Night Hawks seem to get the nod for being noticbly better than the others, especially in the 7" round, by experts on Candlepower Forums.  See this post on Candlepower forums for example
For rectangular replacements for AMC Jeeps SJs and others originally equiped with 6052 lamps, it appears the GE Night Hawk H6054 is one of the few sealed beam halogens of this size that provides the full lamp power of the original 6052 and H6052(65/55 watts). Other H6054s use only 35 watts on low beam. That offsets any advantage of the halogen over a quality sealed beam 6052.

H4 Lamps:
Hella Vision Plus.   I've used these for about 20 years in 7" round on the Barracuda.  Pretty Good. Not sure which bulbs are in now. The original bulbs blew during a grounding short and were replaced, probably with Narvas.   'Virgil' on  Candlepower forums thinks this is a decent choice, maybe even better than other current production H4 offerings.   Note he that he points out they should be aimed to US standards.  The lenses on mine are chipped and I will be trying a set of  the discontinued Cibie z-codes in 2017.. 
Cibie E-code.  I've used these on the Wagoneer for about 15 years (Large rectangular, approx. 5x7").  Pretty good.  Only thing I don't care for is  how brightly they reflect off of reflective road signs.   One got cracked and the reflector oxidized slowly over 10 or so years.    Some experts consider these the best current H4 offerings.  
Bosch H4.  The only other manufacturer that seems to have some good H4 models.  Like the Cibies, availability can be limited.

The four headlight systems seem to have become the most difficult to find good lamps.

Comparing Headlights
A decent comparison of some headlights comes from "Hilldweller's" testing on JK and XJ Jeeps.  He's posted his results and photos on the Candlepower and Jeep Forums.
Each test was done the same way.  The Jeep is parked on the right side of a 2-lane road; camera on hood in front of driver. Lux readings are taken at 12" height from road surface at the edge of each side of the road.  Another reading is made directly in front of the vehicle and for some lamps  he measured the highbeam light at over 100 yards.   The JK uses a 7" round lamp, while the XJ uses a rectangular lamp.   Below is a Summary Table of the Light Output..  

Some general conclusions:
1. The bulb can make a big difference.  Compare the Hella H4s with two different bulbs.
2. Changing vehicle or lamp version can make a difference.  Compare Truck lite in JK (7" round) vs XJ (Rectangular).

Summary of Hilldweller Headlight Lux Tests

Links to Hilldweller's original posts with photos and data below. CAUTION: Jeep Forums can be slow to load.  High Speed Connection or No-script recommended.
Wagner  Sealed Beams (XJ)
Truck-lite LED, improved (XJ)

Cibie H4 Z-beams
Hella H4 with Phillips Xtreme+80
Hella H4 with Delta Blue
JW Speaker 8700 improved
Truck-Lite Improved

    Fog lights

    The advice I got from the rally crowd was to save my money and upgrade my headlights first to H4s.  Only then should I go for fog lights if I still needed them.  It was good advice.  The H4 lamps  put most of the light below the headlight height, and if aimed right, very little will be reflecting off of the fog when on low beam.  Later I found this advice from Scott Harvey in Sports Car Graphic (May 1967) page 70.  Photo at  top.
 "Several makes of European headlights have a very flat top cut-off on both beams.  These lights are as good in snow or fog as any fog light I have used.  Also, they have a relatively low current-draw, so their bulbs have quite a long life.  They are not sealed beam, so they continue to function even if the lens is cracked.  These headlights double as good fog-lights..."  Full article now available as PDF

    My Wagoneer came with Marchal fog lights.  I got one to work, but the lens and reflectors were shot.  I have replaced them with H2 Cibie Tango 40s.  They put out a lot of light, but basically support the light in the low beam area.  Aardvark intl. has graphics showing the light patterns (and dimensions) of each of the Cibie auxiliary lamps.  Let me know if you find the same for any of the others (Hella, KC) and I'll add their links too.
   In use  the Tangos were somewhat disappointing when combined with H4 headlamps. They might have been useful with the stock sealed beams.  With the H4s, maybe they would have been useful in the worst fog, when one must crawl forward at a snails pace.  The relatively high mounting location on the Wagoneer probably would not help with these particular lamps.  In any event,  one had its lens crushed while the Jeep was parked in the city.  Off they came.

    Lamp Efficiency

    Daniel Stern has created a chart showing the light output for each type of bulb, so you can determine for yourself what is better.  Lumens is a measurement of light, that's what counts most.  Watts is power consumed.  So, notice that an H2 bulb puts out 50% more light than an H3 for the same 55 Watts.  So, do you want a auxiliary lamp that uses an H2 or an H3?
    The halogen bulbs do not work well if they do not get adequate voltage.  In other words, if they don't get 13.5 Volts, they don't draw 55 Watts and don't put out the lumens listed.  Below 12 volts, they are very unhappy.  Stern also has a big chart of small bulb types.
     Virgil has posted some test results of H4 type bulbs on Candlepower forum.

Volts, Amps, Watts?  Watts it all mean?  Ye old electrical analogy:

    Think of Volts like water pressure in a pipe or garden hose (psi), and amps as the flow rate (gallons per minute).

    Problem solving on the Barracuda

    After staring at the shop manuals long enough, and reading and asking around, I decided to go install a relay system.  That seemed much easier than rewiring behind the instrument panel.  I already had a big hole melted in my headlight switch connector, and wasn't impressed with what the wiring diagrams indicated.  A 14 gage wire carries most of the current into the headlight switch, and a 16 gage carries it down to the dimmer, where it drops to two 18 gage wires, one for high (red) and one for low (black).   The connection that had failed was on the 14 gage input wire.  That said to me that I would have to beef up that wire as well as the ones coming out of the headlight switch, and each and every connection would have to be gone over, including the ones in the firewall connectors.  The engine harness was replaced about seven years ago with a nice repro from Year One.  Its a good repro. and every bit as inadequate as the original.
    Once the electricity is done with the headlamps, it has to return to ground.  The original design is not so bad here.  Each headlight got its own ground wire (black with white stripe) that goes to the radiator support and is held on with a sheet metal screw.  If there is paint underneath, or the screw doesn't tight anymore, or its corroded, then the final connection will be bad.  Also, realize that the only connection back to the negative of the battery and the ground of the alternator is through the engine block, and the only electrical connection from the body to the engine is the little strap way over on the firewall.  Running another ground wire from the battery negative to the radiator support can only help, and can be done very discretely.


    Relays are remote switches.  Send them power and they turn a switch, Turn the power off, and they turn the switch off.
So, in a relay system, the high beam power is used to turn on the high beam relay instead.  Ditto with the low beam.  A relay only draws a drop of current so what was barely adequate becomes super overkill.  The real power is fed to the relays directly from the alternator (or battery) using as heavy of a wire as required AND a circuit breaker or fuse. It is almost always preferable to supply the power from the alternator rather than the battery. see Charging Circuit


    The hardest items to find are good grade connectors and relays.  My sources were West Marine Discount, Waytek Wire, and Radio Shack.   Marine duty stuff is more moisture resistant, the wire strands are all tinned, and sure it costs more.
I was going to use the automotive circuit breakers that reset themselves (just like the ones in the Chrysler and AMC/Jeep headlight switches)  but instead went for the buss fuses in a sealed marine fuse holder.  Tough call for me.
    Relays can be purchased in two patterns, 5 terminal and 4 terminal.  In both, two terminals are for the signal, in & ground.  In the 5 terminal, the two outputs can be arranged to be both on and both off.  That can simplify wiring.  One can go to the left light and the other to the right light. Or, one can be used to feed your auxiliary lamps.  That way, your fogs can only turn on when the low beams are on, or your driving lights only when the high beams are on.
    But, be careful when buying 5 terminal, they also come as double pole (DPST).  In this arrangement, one output is on when the signal is on, and when the signal is turned off, the other output is on.  Something is always on. Ooops.


    I couldn't find a good replacement for the headlight connector.  The one NAPA carries was unimpressive, although its been suggested since then that Autozone may carry a decent one.  I disassembled the harness, and used my original Chrysler harness as reference.  If you don't have two harnesses. then you will want to do some careful measurements or trial fits of the wire lengths on the car.

   1.  Removed the headlight bezels and headlights.
    2. The power for both headlights goes into the drivers side headlight socket.  The wires out to the left headlight is crimped together with the power lead on to the connector.   So the bundle going to the connector has two reds wires (high beam in, left high beam out), two black wires (low beam in, left low beam out) and black with white stripe (right side ground).  I decide to use the original wires to signal my relays on the left fender.  Since I wanted the socket, I clipped the wire bundle, and reconnected the reds and the blacks by soldering.  The ends were then sealed with liquid electrical tape and cold shrink tape.
    3. The left head light wire bundle was also clipped, but only an inch from the connector.  The leads were then ran to the left fender.  Connectors made for the relay sockets were then crimped and soldered on.
    4. Fun part. not. Slipping a cotter pin in the flat T of the headlight connector, the catch was depressed and the metal clips pulled out.  This is when I found the crimps on the new harness weren't that great.  In fact the Chrysler crimps were observably better upon close inspection.  Then each metal connector was gently placed in a wood jaw bench vise, and the crimps opened up.  I used an ice pick and small screw driver working in parallel to the wires from the insulation crimp toward the front.  It is possible the Packard 56 series 12 gage connectors would work here.  The 14 gage ones are too small, but otherwise look and fit right.  Made up a new high and new low beam wire out of 14 gage wire connecting  the relay connector to the head light sockets.   Instead of joining the wires in the headlight sockets, I spliced them in line.
    5. Made up two 12 gage wires with in line fuses to carry power from the alternator "bat" stud to the relay connectors.  The connectors were only for 14-16 gage, but by soldering as well crimping, I am sure I have very good connections.  Same with the 18 gage signal wires soldered to the same  14-16 gage connectors in step 3.
    6. Made up a bracket for the relay connectors with some sheet steel and  some old rubber feet electronic cabinet(radio or something) .  Holes already in fender from former air conditioning  system.
    7. Made up new ground wires for each headlight, a new ground to from the battery to the radiator support (12 gage marine wire soldered to a very sad and corroded unused lead on the Belodon battery cable, soon to be replaced).  Made a second  ground point on the battery side of the radiator support just for the headlights using a self tapping machine screw and nut left over from the speaker replacement on the Grand Wagoneer.  see, AMC still helping Plymouth ;)


'67 Barracuda Main Page
'85 Grand Wagoneer Main Page
Charging Circuit with Ammeter

Oct 13, 2001 rev May 2017