41 mercury just starting out

rdmace1956

rdmace1956

Member
I brought home this 41 Mercury 8 that I recently purchased from Father-In-Laws estate. Has been sitting for three years now but was a real nice restoration. The only problem at the moment is 12volt negative conversion was only partially complete when he passed away. I will have to try and see what is there and finish it up. Starts and runs good, just no running lights. Has working 12v brake lights and turn signals though so OK for daytime.

Would like tips on where to find good wiring diagrams (for the way it was from factory), basic service manual with brake adjust info and stuff like that.

Jim was a life long mechanic who knew cars inside and out. Did all his own work. After his retirement he had a barn full of Model Ts that he fixed up and trailered around to events, and this was to be his touring car. he went on a few long trips and enjoyed it for several years after he restored it. He was a fanatic about engine restores and I have no doubt it was gone over with a fine tooth comb before it ever started.
 

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Thanks. my friend thought the merc should have had a headlight relay under the hood somewhere. I will have to look at the switch again and see if he was going to run the full current thru it.
 
Relays weren't used by FoMoCo in that time frame. They just had circuit breakers for the system protection but the main switch did most of the current distribution at that time. Modern vehicles use relays but one would have to be added on a 41 or even most of the cars manufactured in the 50s for that matter. For single sealed beam headlamps, a person wouldn't really need a relay unless they just absolutely have to have one.

It looks like a lot of wiring is one color vinyl covered wire. A person might be able to get a harness with the modern wire in colors that match the OEM diagram. Tyree Harris is a good one to check with on wiring harnesses. Original type cloth covered are available from several different sources.
 
yea, i would like to get back to an original harness as much a possible. The running light/ chassis sections seem to be intact but I don't think he used much of the cowl and under dash wiring that should be there.

I will need to hook up the old 6V heater fan pretty soon or dress warmly.
 
I don't remember but it seems like he was putting the car back together in about 2005 time frame and purchased a reproduction harness at a show or by mail. He did not do the interweb stuff. As I recall the harness had a lot of issues (I don't remember what) and maybe he ended up making a lot of it on his own.
 
Good news, thanks to the wiring diagram I was able to get power back to the headlight switch. Swapped the headlamps for 12V Halogens that fit perfect. Taillight bulbs had already been converted. I ran two modern fuses a 20 amp for the headlamp feed and a 15 amp for the running lamp feed. The original circuit breaker was still there but I was not sure if it would work correctly.
Two minor issues. The park lamp terminal on the switch is staying hot all the time. It worked for while then seemed to hang up. I was not sure why the park terminal is separate from the tail lamp terminal but the wiring diagram showed that it is an original style switch. The headlamp and taillamp terminals seem to be OK.
One park lamp bulb is not lighting up. I could not figure out how to get the glass lens out to check it, The bulbs may still be 6V,
No interior lights except pillar lamps. I probably will leave that for a major rewire with 6V reducer, etc.
Thanks to Mike AZ for the diagram. It made it possible. I need the car for daughters wedding Saturday. Could have gone without headlight as it is afternoon wedding but this will make it much more flexible that evening. I had planned to leave it town but now I have the option to drive her home or move it at night if need be.
 
Halogen headlights can draw more current than the lighting switch was designed for, you might consider installing relays for the headlight feed.
 
Standard sealed beams are no problem for the old switch but as previously mentioned, the halogens are a problem. 12-volt sealed beams are easy to find in the same sizes as 6-volt and they are plenty bright enough. The circuit breakers don't care what voltage is in the line. They just care whether there is a short. You can still find bi-metalic type circuit breakers at about any truck stop. They are usually 15 amp but there are other ratings as well. FoMoCo used them so that the lights could still work if a person found & fixed the short. Once a fuse is blown, it's time for the deep six.

You should be able to find 12-volt bulbs any any of the styles that the old 6-volt types were available in. GE used to make a bulb chart that gave all the part numbers and the different voltages that were available in each terminal type, candle power, & glass bulb shape. There may be one on line somewhere. Ford only gave folks the FoMoCo part number for bulbs so you had to find the replacement part numbers on your own. They never invisioned a change to 12-volt until 1956.

Wiring harness (singular) is kind of a misnomer. There are actually a large groups of separate harnesses required to rewire an old vehicle. Tyree Harris or Rhode Island Wire are the folks to talk to if you are going for a decent one that matches the OEM or at least the diagram for color code.
 
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I should have mentioned. It turned out the double fuse holder you see in the firewall photo had a intermittent (mostly bad) connection in the holder itself on the side he was using for running lights. I bypassed it altogether and put the fuses inline for now to 'simulate' the Ford breaker unit under the dash.
I could not figure out how to remove the glass lens on the front fender parking lamps. I quit for now because I did not want to mess them up before the weekend event. The one that is not working must have had a leak issue, I saw some silicon sealer had been used on it.
 
Looks the same as my '41 Ford. If you take out the screw on top of the stainless part of the parking lamp, the stainless part will lift out from the front. It is tabbed at the back. But it is probably stuck from sealant in a generally futile attempt to keep the light from leaking. Go around with a thin knife. Then the glass will come out, again reluctantly if there is silicone. Buy at least one spare glass lens, as there is a pretty good chance you will break the one you are trying to remove. They are readily available, and cheap. There are also replacement gaskets, but they are flimsy and unreliable in their water sealing duties.

I converted my '41 Ford from 6V+ to 12V- ground. Regarding the heater, I installed a CPT C240607 DC/DC converter. It will provide up to 7 amps, which is plenty for the heater. I used the same unit to convert the electric windshield wiper motor. Both work fine.
 
Yes, thanks to all for the great advice. Father In Law put a lot into this one. I am thankful that I spent enough time in his shop to pick up a few things. Hoping to take good care of it and keep it looking good and original. He was a real restorer for the Ts and As and quite the body man using old style lead and brass fillers.
 
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