Halogen headlight Conversion

I find the stock headlight pretty weak so interested in if anyone has done a Halogen headlight Conversion.

WCCC has this kit that looks to include everything needed https://secure.cougarpartscatalog.com/halogen-headlight-conversion-complete-kit-repro-1967-1968-mercury-cougar.html?attribs=75 but no reviews or anything recent here on the topic.

I do not want to stray too far away from stock as my 67 is “fairly” original aside from mods made to make the cat more usable in the modern world and this looks like one of those “mods”.

So long as you have a relay to power the lights the improvement is incredible. I would look at doing the electric headlight doors as well if you can afford it. The combo kit is fantastic.


I did this conversion on my 71 using a little different bulb. They were still a 55w low and 60w high with the relay. Improvement was fantastic!! Install was easy and the relay works great as well. I have a voltage gauge instead of the amp and turning on the lights and going from low to high shows a bump in the meter but no dimming at a light or with turning in the heater motor. It is easy to hide and unless you look real close the H4 looks just like a sealed beam.

Rocketman also has relay kits.


Bill can’t you run the H5006 & H5001 w/ out the relay? I was talking w/ Vic about this & he stated you can run the H5000 series bulbs w/out relays. They won’t trip circuit breaker as they don’t draw as much as other “kits”. . Not saying relays are bad. Just wondering if the original system can handle low draw halogen bulbs for less than $10 each, why not? Anybody run a comparison? bright vs voltage?

Inquiring minds want to know these things!..

From the article I wrote for LCM Volume 1 Issue 6:

The circuit that feeds the headlights includes a circuit breaker that is incorporated inside the headlight switch. The breaker is rated at just 15 amps. That means the maximum amount of power your headlights can consume before triggering the breaker is about 180 watts total. The lowest power consumption low beam halogen replacement pair (H5006) consume 70 watts. So far so good. Turn on the high beams and the trouble begins. The (H5001) high beams check in at another 100 watts. This puts us dangerously close to the 180 watt limit. The result, turn on the high beams, and chances are, your entire headlight array will shut down until the circuit breaker cools down and resets, or you drive into a parked car which ever comes first.

Halogen bulbs are very sensitive to operating at optimum voltage. A slight drop in voltage can produce a very large drop in output. The recommended voltage for halogen headlights is 12.8 volts, and the maximum is 14.6 volts. 12.8 volts is higher than the output of a fully charged battery. This means that your alternator and voltage regulator must be operating properly.

Our Cougars route the power for the headlights from the starter solenoid through the main harness to the inside of the car, and then through the headlight switch and then back through the firewall to the headlights. This long path results in a drop in voltage. Modern cars do not route power this way to avoid the voltage drop. Instead they use relays, sort of remote controlled switches to enable much more direct wiring paths.

Did they all do it that way back then?

Mostly… All Cougars certainly.

I have Wagner halogen lights in our 3 '69 Mercurys-a Cougar and 2 Cyclones. I assume these are the H5000 series lights purchased and installed many years ago. I haven’t had any problems and have plenty of light and even more when I hit the high beams.
No doubt if I wanted to run the night shift at LeMans I’d need more light plus a lot more.

Is there any original equipment looking LED substitute available?

Bill. Like your thinking and quite sure you are correct about a relay being needed for this conversion but did you use Rocketman’s “HRKP-A - Headlight Relay Kit with electric motor control for 67-68 (dual motor) models” (or whatever is correct for the year of the cat you converted) for doing both halogen headlights and electric doors or something more home grown?

Now that i look what Bob is offering thinking going with this kit would be the way to go. No plans to convert the doors to electric right now as the vacuum system is still working fine but small price to pay for the dual relay and have the option to go electric with the doors later.

No one will see the headlights unless on but still want to maintain somewhat of an original look.

Not really hearing too much of a downside on doing this. But too bad that Scott Drake is currently only making halogen headlights with FoMoCo markings in 7" for Mustangs Scott Drake C0DZ-13007-A Scott Drake Headlight 7" Round Halogen Sealed Beam with FoMoCo Logo as would make this a no brainier.

I have Bob’s relay set up in my 68. They work fine unless you run 4 x 165W globes in high beams as they exceed the internal safety circuit Bob has built into the units and the headlight doors will close. I dropped globes to 2 x 95W and 2 x 120W and they work OK.

How crazy. I had no idea.
My son and I installed Halogen headlights a few weeks ago (not knowing they were NOT the original type of lights.
They were $10 each at O’Reilleys.

No problems until this evening when I was driving down my street with the highbeams on.
After about a minute of the highbeams on… the lights went out.

I turned the highbeams off (foot switch) and about 5 seconds later… the headlights came back on.

What do I need to fix?

Replace the headlight switch.

Also, or, get the relay kit.

Thanks both. As I have no idea where either are… can anyone provide links or images?
Still learning all this.

Scott Zeller wrote a nice article on installing the Rocketman relay kit. Visit the CATS web site here: http://www.catsccc.com/how-to

Good write-up, got it saved for future reference.


Thanks…the relay is working real well for my 69 and I was very happy with the ease of install and quality of the relay/headlights. Go for it!