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Old 10-11-2020, 04:37 PM   #1
KenBolton
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Default Headlight Focus Procedure

So far Iv found three different alignment heights from three different sources. 33, 37 and 39 1/2. Which is correct?
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Old 10-11-2020, 05:05 PM   #2
duke36
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Default Re: Headlight Focus Procedure

Ford Service Bulletins ?
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Old 10-11-2020, 05:42 PM   #3
Patrick L.
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Default Re: Headlight Focus Procedure

We've always adjusted them at 25 ft. A few inches down and a few inches to the right from the center of the light.
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Old 10-11-2020, 06:03 PM   #4
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Default Re: Headlight Focus Procedure

The owners manual has the correct procedure. They are cheap to obtain and a big help.
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Old 10-11-2020, 08:00 PM   #5
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Default Re: Headlight Focus Procedure

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Originally Posted by duke36 View Post
Ford Service Bulletins ?
The January, 1928, Ford Service Bulletins have the procedure for the first type of headlights that Ford used, the ones with the vertical fluted lenses. Most guys don't use these lights and lenses on their cars today because they only give "high beam" and "parking lights". They don't give any dipped light for driving without blinding oncoming drivers. The instructions for these lights align the top of the bright part of the headlight beam at a line 33" up from the ground and 15" left and right of the centerline of the car. The face of the lamps is 25 feet from the wall.

Later, in the February, 1929, Service Bulletins, they say to aim the fancy new Two-Lite headlights with the bright beam areas 37" above the ground and centers 15" left and right of the centerline of the car (also measured 25 feet from the wall). These are the type lights that most Model A owners use in their car because they have a Low Beam that you can drive in traffic without blinding others. You aim the High Beam properly and the Low Beam is automatically correct.

That is why you are finding conflicting information about aiming the lights. There were 2 different light systems used on the Model A, with different aiming levels.

I don't know where the 39-1/2" number came from. AA trucks, maybe?

Hope this helps.
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Old 10-11-2020, 09:14 PM   #6
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Default Re: Headlight Focus Procedure

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The instructions above are for original type bulbs with filaments of original shape and location.
Most replacement bulbs sold today have filaments that are shaped different, and at a different height, so unless you are using the correct old stock bulbs you may or may not get them to focus properly.
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Old 10-12-2020, 09:46 AM   #7
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Default Re: Headlight Focus Procedure

Center height of headlamps for 28-29 is 37-5/8", 30-31 is 38-11/16", which accounts for some of the difference. Also H-type and TwoLite use different bulbs, as 1930 coupe says.

http://www.motormayhem.net/model-a-f...pecifications/

In either case the lamps will have a slight downward tilt. Proper focus should produce an 8" diameter bright spot (without lens), regardless of distance.

Last edited by Badpuppy; 10-12-2020 at 10:16 AM.
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Old 10-12-2020, 01:08 PM   #8
MikeK
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Default Re: Headlight Focus Procedure

As many of today's A's have different tires and who-knows-what springs, the ground to center height of lamps on your particular vehicle may vary from what came off the assembly line. Keep this in mind before blindly following some distance/beam height spec.
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Old 10-12-2020, 03:51 PM   #9
Kurt in NJ
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Default Re: Headlight Focus Procedure

Easy way to do focus is to take the lens off, properly focused will have defined round beam with almost no light going anywhere else --- less than twice reflector diameter at about a car length. When the lens is put back on the pattern will look like the picture
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Old 10-13-2020, 11:16 AM   #10
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Default Re: Headlight Focus Procedure

I have to chuckle. We might blind on coming traffic WITH A 32 CANDLEPOWER BULB!

With some of the lights they install on todays cars, now that is blinding.
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Old 10-13-2020, 11:20 AM   #11
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Default Re: Headlight Focus Procedure

Anyone ever made a fixture like the factory used for aligning the headlamps? Just curious.
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Old 10-14-2020, 10:21 AM   #12
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Default Re: Headlight Focus Procedure

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Originally Posted by KenBolton View Post
So far Iv found three different alignment heights from three different sources. 33, 37 and 39 1/2. Which is correct?
I measure from the floor to centre of the headlight and use that measurement.
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