Adding Guages
 

Am thinking of adding the temp and oil pressure gauges using the bracket that mounts under the instrument panel. How do you run the lines inside the car so that they don't show very much? Where do they go through the firewall? I have a '31 S/W Town Sedan.

Re: Adding Guages
 

JD, I used magnetic cable/wire holders in many areas of my car. Works great under the dash/gas tank, firewall, frame etc. Having the wires in a loom and using these "clips" made for a very neat installation. Got them from Del City

https://www.delcity.net/store/Magnet...SABEgIYZPD_BwE

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Mounting under the instrument panel is a direct shot to running the lines directly through the electrical junction box into the engine compartment. I have a temp gauge and that is the route I took. Two lines might be tight depending on the lines.

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JD, I have the same car as you, I used the route that Magicbox suggests.
I only use the temp gauge, as the Model A uses a non-pressurized oil system so a gauge is of little use.
It's a quick and easy install once you have all the pieces, just be sure to get a good quality gauge, I cheaped out twice and now I have two broke cheap gauges and one quality working gauge.

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The only reason to have an oil pressure gauge is to panic passengers when it reads 0 to 5 PSI. I have a volt meter and vacuum gauge. The MotoMeter is more than enough for water temp.

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I agree with those that believe an oil pressure gauge is not necessary. The oil pump in a Model A is like an elevator, it elevates oil up to the valve chamber where it lubricates the valve stems, guides, and springs. The oil then runs down through ports in the block to lubricate the main bearings. The excess oil then pours over the front onto the timing gear to lubricate it. The rods are lubricated by the dipper trays. There is not much in the way of oil pressure to be seen on a gauge.

I am not in favor of the gauge mount that fits under the dash. It looks like a knee bumper to me, plus it is hard to see the gauges there. A better location is right under the dash rail. There are a number of bolts located there that a fabricated bracket can be attached to. It is also a better location to view a gauge.

A temperature gauge is absolutely necessary. Another gauge Henry forgot was a tachometer. He also did not provide a back up camera and a GPS. The GPS also provides a speedometer at eye level.

The attached two articles show how all this can be remedied.

Tom Endy

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Hi Tom. In your article on the Tach it states "Two wire leads from the tach attach to the two coil primary terminals". Does that mean your tach is 'Hot' all the time? Neg side on coil is connected directly to terminal box on Pos ground system? Please explain.

I had to rewire so my ignition switch was 'before' the coil instead of 'after' like a original Model A should be wired so my tach was not powered up all the time.

Re: Adding Guages
 

My Victoria is wired as Henry ordered. It is six volt positive ground. The ignition switch is electrically below the coil. There is always voltage sitting on each coil primary terminal. When my tac is connected the two wires also see voltage. However, there is no current flowing thought the coil or the tac until the ignition switch is closed and the points are closed. The tac does not become active until it sees a pulse from the primary winding of the coil. That only happens when the points close. When current is flowing through the coil, one terminal is momentarily at ground.There is no other ground on the tac so there is no current flowing through the tac when the points are open or the ignition is switched off..

Tom Endy

Re: Adding Guages
 

Thanks Tom for the explanation. My Tach has an integral light in it and when wired as you have it the light stays on. But it seems my Tach also has a ground wire and yours does not. So I rewired so the switch is before the coil and the coil does not see voltage until the switch is turned on. That is why I asked.

Re: Adding Guages
 

It may take a half second longer to look at all the gauges with them mounted all over the place but the only one I need in autocross is the tach.
I like these locations because all the wires and pipes for the gauges are out of sight except for the tach.

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For me , the most important gauge that can be added to the model A is a coolant or temperature gauge . I do run an oil pressure gauge in my 31 tudor but figure that it is mostly useless because oil pressure is very low on an original model A engine . The oil pressure gauge is mostly useful to show if engine oil is real low . I never need to add oil between oil changes on my overhauled model A engines . I'm not racing , so I really don't need a tachometer . Just my thought but I feel that too many gauges takes away from the original look .

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Ruth' Can you show how you wired the coil after the ignition switch? I sketched this out and found that I would have to break into the ignition cable that goes to the distributor to do this. Not sure this is possible. Jack

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I like your gauge set up but what really caught my eye was your steering column support...was that a commercially obtainable product or is it something you have made up ? if so, I would be most interested to see it in detail . Mt car is right hand drive and your bracket looks to be adaptable for both sides.many thanks
Vic....NZ

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Hi Jack. Here is the wiring diagram I used to rewire my ignition switch. I didn't draw it. I copied it from a thread on electric gas shut off valves.

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If the gauges pictured belonged to Y -Blockhead , I meant no harm in post #12 .

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Well that didn't work so good. See if I can make it bigger.

Looking at the diagram, I'm wondering if the 'new lead' shouldn't be on the other ammeter terminal like original... hmmmm.

https://live.staticflickr.com/65535/...6f2650a5_c.jpg

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Ruth ' thanks for the reply but the line to the points goes through the ignition switch and it has to be broken and tied directly to the coil which is where I have my problem. This is the same as I figured out but to put a line from the coil through the ignition switch housing that's hooked to the wire that goes to the points and another pair feeding power to the rest of the car which also has to go through the switch to be turned on and off'. That makes for three wires in the ignition switch housing which I don't think is possible. Jack

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Pete,

I like that your tach is redlined at 7200 RPM. :D

David Serrano

Re: Adding Guages
 

The attached drawing shows the Model A electrical system in a simple diagram as Henry designed it. It is shown as a positive ground. By reversing the polarity designations at the battery it becomes a negative ground. It can be either six or twelve volts.

The way Henry designed it was his idea of theft prevention. The ignition switch when switched off puts a ground on the points. The wire from the ignition switch to the distributor is protected by an armored cable. The cable is attached to the engine with the number 8 head bolt. This makes it extremely difficult to hot wire a Model A. To do so you would have to unbolt the cable from the engine and remove the distributor to unscrew the distributor from the cable; then reinstall the distributor and screw in a bypass cable with a jumper wire that would clip on to the low side of the coil.

This design does not allow for any electrical accessory to be attached to the ignition switch because any device attached there would be drawing current thought the coil and be arallel the ignition points.

In order to have accessories attached to the ignition switch you would have to do some rewiring of the circuit. There would have to be a direct connection between the coil and the ignition points and the ignition switch would have to be above the coil and switch power to the coil on and off.

The Model A would them be easy to hot wire.

Tom Endy

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That was a good flathead. After I sold it, it went on to win the 4 banger top fuel class at the Antique Nationals.

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Moto meter is all you need. Oil pressure gauge basically useless on A. Oil pump is bulletproof and none of the bearings are pressure fed anyway.

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If I am understanding you correctly you want to route all your power thru the ignition switch? I don't think you should try that. The switch wasn't designed for the many amps.

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I am starting to install a volt meter and a water temp gauge on my 1929 coupe and seen these posts. It seems like an oil pressure gauge is useless. The oil press and distributor are both run off of the cam shaft, if cam or distributor stop working it really doesn't matter if you have oil pressure or not, engine quits you lose pressure, engine runs you have oil pressure...am I thinking right or not?

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It wouid be worthwhile to at least have an idiot light for oil pressure (IMHO). Another scenario to the ones you cited would be engine oil level is very low or crankcase is empty. The engine would be running with zero oil circulation and would seize. Maybe we are spoiled by modern engine monitoring systems, but knowing engine oil pressure and engine temperature at all times is good info which was not known on Model As but did become available with standard equipment on cars a short time later.

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The oil pressure gauge is one step up from an idiot light. You learn what your normal pressure is, and then if the gauge indicates a drop in pressure, you stop the car immediately until you figure out where the problem is. Could be oil pump failure, could be a leak, etc., but either way the gauge is telling you to stop before the lack of oil flow damages the engine.

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To figure out how to wire an A so that the coil is after the ignition switch, search "8n wiring diagram", which is for a tractor. Sorry, I don't know how to post it here. All that's needed is a different junction block which costs a few dollars.

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Is this what you are referencing?

http://www.ntractorclub.com/howtos/p...m-Lawrence.pdf


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Re: Adding Guages
 

One more note about oil gauges - in Fahnestock's "Unauthorized Accessories," the only two gauges advertised are oil and temperature gauges. So there seems to have been demand for oil gauges at the time. There are also red/green idiot lights for detection of low oil pressure.

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Personally I don't like the flashy look of modern gauges in a Model A.

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I wonder if low oil pressure switches for indicator lights are set low enough for the Model A or would the light be on all the time. Mine only shows ~2-3 psig at idle

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There were contemporary lights that were sensitive enough.

Attachment 452990

PS - I assume "indicates generator and fan belt trouble" means like "if the light is off, you have generator trouble."

Adding Guages
 

Wow. I didn’t know the “idiot light” was available way back in 1929. I had just assumed it was a late 1950s thing. (I think my 1957 Fairlane had idiot lights.)

Thanks for sharing.

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Someone tried to steal my moto-meter, and broke the neck on my nearly new radiator. $500 bucks shot. I have a new radiator, and a gauge now... I sure miss my moto-meter though.

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I have heard that Henry didn’t think a temp gauge was necessary, nor was a motometer, which he resisted offering. His comment, supposedly, was, "Any fool can look out over the hood and see if the radiator is boiling over or steaming." Anecdotal, maybe.