Topic: Polarity check

flatcreeker	-- 12-05-2021 @ 2:39 PM
	I have a digital voltmeter which resembles the traditional continuity tester (type with battery/light in plastic handled ice pick with lead and small alligator clip0). This voltmeter has LED voltage display in handle and also has two LEDs indicating polarity: green=pos ground, red=neg ground. Can someone out there in EV8F land tell me if and how I might use to read polarity of generator polarity without removing either either lead from a two wire generator (thereby eliminating need to polarize if already correct polarity)?
40 Coupe	-- 12-06-2021 @ 4:50 AM
	Starting with your voltmeter. Does it have a switch that will allow the voltmeter to read DC or AC? Typically digital voltmeters do not like the DC produced by generators and our running cars, due to the amount of static produced by the generator brushes and the high voltage in the plugs plus arcing in the distributor. The best way to determine if the generator is working is to connect a analog DC voltmeter to a good source of battery - and ground+ Discharge the battery slightly by turning on the headlights for several minutes. Then start the car and read the voltage at idle and then increase engine RPM watching the voltmeter and the voltage should increase to about 7. volts and stop even if RPM is increased further. If so the generator is charging and the regulator is limiting properly. It is best to give more information when asking questions. Info such as vehicle year and voltage of the battery can be helpful in a reply.
flatcreeker	-- 12-06-2021 @ 8:14 AM
	Thank you for your timely and considered response. I am new to early Fords and haven’t pulled wrenches in 35 years. I’m learning a lot but not fast enough. Mine is a 39 Mercury fordor survivor with 169K on the clock. The “icepick” volt meter was intended for automotive use and I have used on both 6v pos ground and 12v neg ground. There are no switches. I have used with engine running and off at battery and regulator. I have checked against my Fluke multimeter and vintage analog volt/tach/dwell meter and they are all in agreement (to a surprising degree). I disconnect the battery whenever I work on the Merc and figured there must be a way to use the polarity feature to verify polarity of generator after reconnecting the battery. I’m wrestling with a solid-running engine stumbling once engine is fully warmed (after 15+/- miles of moderate driving from stone cold in 55-70F ambient) so I’m under the hood a bit. I’m not confident in my electrical skills enough to just start poking connections with the pick. Thanks!
flatcreeker	-- 12-06-2021 @ 8:40 AM
	Better photo, engine off battery 6.4 volts, max charging measured at battery is 7.0 volts. Would prefer about 7.4 but will accept 7.0 rating than start tweaking regulator.
TomO	-- 12-06-2021 @ 8:51 AM
	If your battery is connected with POS post grounded and your generator is charging it, the generator is the correct polarity. If your battery is discharged after a short drive, your generator might have polarity reversed and you would have to polarize it. Did you get your voltage regulator situation resolved? Please expand on your stumbling issue. Does the engine have a miss at constant speed above idle? Does the engine miss only when you try to accelerate? Does it seem that the engine is starved for fuel when you try to accelerate? Tom
flatcreeker	-- 12-06-2021 @ 10:16 AM
	Greetings TomO! My regulator matter is resolved. I went through 2 new "blue top" regulators without success, destroying them in the process. I found a N.O.S. P&D regulator and after installing and polarizing generator had nothing, cutout not closing at any engine speed. After removing cover and tweaking achieved 7 volt max charging and proper "cutout" function. Would like to have 7.3v - 7.4v max but unwilling to keep live-running tweaking. The P&D regulator was much easier to tweak due to the heavy gauge construction resulting in more force required to bend spring tab so "over-bending" less problematic. Not the best way to do generator/regulator I know but it's what I had. I tried engine off, battery disconnected method but after two days I went "live". After two tweaks I had 7.0v and I said: "good enough". It's been enough to keep battery charged fully charged to 6.4v with surface charge removed. Just immediately prior to the regulator problem (in fact, it could have happened simultaneously and I just didn't notice change in batt dash gauge), I had an engine stutter develop. It was what I shall characterize as a "snap" stutter which would occur repeatedly 1 - 2 seconds apart upon acceleration in 2nd and 3rd. I went through a litany of ground connection verification, spark cks, plug replacement, etc.. The overwhelming body of forums says suspect coil. I installed my spare coil (Skip Haney rebuild). I had a n.o.s. in the box (believed to be good) NAPA Echlin condenser I used . No change in condition. I have since acquired a vintage FoMoCo N.O.S. in orig box condenser which I intend to install next, absent any other good advice. The engine runs strong from cold until stutter occurs. From stone cold, it generally takes 2o miles of calm driving in ambient 55-70F for the stutter to begin. If I let it sit for 3-4 hours and then drive, it starts within a 2-3 miles. Sometimes under hard acceleration in the upper rpm range in 2nd or 3rd it doesn't do it. It has experienced several high voltage events in the 9v range during the blue top regulator attempts. I do think I have a weak fuel pump due to slow to start sometimes. I have not done any fuel pump testing. I have a N.O.S. fuel pump push rod which I intend to install (after verifying length) if and when I remove the pump. I have experienced no low fuel fades during road running. Did experience some difficulty stalling at idle while working on regulator. I have a spare Skip Haney distributor/coil with Skip supplied condenser which I have considered installing. Whatcha think?
37RAGTOPMAN	-- 12-06-2021 @ 10:27 AM
	missing in engine, did you clean the spark plug;s and what heat range ? seems to me it is a spark plug problem , or sticking valves, has the engine been rebuilt , new valve guides,? maybe fitted to tight,ok when cold, but with heat not so good block expands and tighten the valve so they do not more fast enough and case a stutter,? do you hear any noises , from the air cleaner or the tailpipes ? let us know, could use more information to dianois the problem my 2 cents 37Ragtopman ,Maine,
40 Coupe	-- 12-07-2021 @ 5:26 AM
	I do not believe you engine miss is from the generator. If you have just over 7V charge your good with electrical charging. Do check out the fuel pump and fuel lines especially the pump input flex line. Make sure there are no air leaks or pin holes in the fuel line.
flatcreeker	-- 12-07-2021 @ 6:57 AM
	Thanks 40Coupe. Didn't mean to throw a curve ball re the generator. I have no problems with the generator, I'm just trying to learn if I can (and if so how) use my device (since it indicate polarity when used) to determine generator polarity. I am electrically challenged but have this nice little instrument I want to exploit.
marko39	-- 12-07-2021 @ 10:29 AM
	Don't assume a condenser is good just because it's new. Especially nos. or nors. ones that are decades old. Have them tested to be sure. I tested about 10 nos. and Nors. And found most of them bad.
TomO	-- 12-07-2021 @ 2:41 PM
	If I read your response correctly, your miss occurs when driving at a steady speed or when accelerating and only happens when the engine is at operating temperatures. You can try pulling out the choke a little (1/4 -1/2 way) to see if performance improves. If it does, your problem is fuel starvation. This can be caused by a weak fuel pump, vacuum leak in the flex line to the fuel pump,a vacuum leak in the line from the tank, plugged fuel line from the tank, plugged flex line or plugged fuel pick up in the tank. My first try would be to check the flex line, if it is hard and the outside is cracked, I would replace it. Next I would try to clear the line going back to the tank using compressed air. You can buy small cans of it at stores that sell computer products. If that worked, I would consider having the tank cleaned and sealed and replacing the line from the tank to the firewall. You can also check the spark when the engine is at operating temperatures. If the spark is good at idle, check it as you increase engine speed. If the spark is good, I would examine the inner caps for wear and for traces of cross firing. If these are OK, install your spare coil, distributor and condenser. Make sure that the bolt with the condenser grounding is tight. If that fixes your problem or changes the symptoms, send your current assembly to Skip for repair. Tom
flatcreeker	-- 12-08-2021 @ 6:27 AM
	The problem first occurred while on a 75 mile drive after about 40 miles. This, after about 1,100 miles of smooth running since I received the Merc. The problem only occurs under acceleration. There is no fading or sputtering like I associate with fuel starvation but a sudden snap-stutter, repeating every second of so until I stop accelerating, without regularity likely because I stop accelerating.. I may be imagining it but once it starts, I sometimes believe I can "feel" some weakening of power just cruising along, not accelerating. It doesn't do the snap-stutter when parked and accelerating from idle. Before it starts, it runs like a lion. Once it starts, it seems to require less accelerating to initiate. I have tried the application of various amounts of choke when the stutter occurs. It sometimes seems to make a slight, temporary improvement but enriching the mixture doesn't resolve the problem. I have replaced the paper element filter (in-line between the pump and carb which I cut open for inspection and found clean), removed and cleaned the glass fuel bowl (which had a tiny amount of ultra fine black dust about the consistency of graphite in the bottom of the bowl) and inspected the screen, blew out the fuel line to the tank, and assured the fuel tank cap vent was open. I plan to eliminate the in-line fuel filter and install a steel line obtained from 3rd Gen. I plan to go over the fuel line as you suggested. There is bit of rubber fuel line with screw type clamps in the steel line near the tank where once was installed an electric pump. Will be away much of December so it may be a bit before I can return my attention to this cursed matter which stands between me and the road. I had hoped to move the Merc to Savannah for the winter but only if it's reliable as my wrench is here at the cabin. Thanks, TomO, for your continued counsel.
TomO	-- 12-09-2021 @ 8:45 AM
	Missing that occurs only when accelerating is usually carburetor related. It could be a vacuum leak, bad power valve, float level or fuel starvation. Charley Schwendler in New York seem to do the best job of rebuilding carburetors for these cars. To check fuel delivery, you need a graduated 16 ounce or larger container to determine the amount of fuel delivered in a measured time. Disconnect the fuel pump line from the carburetor and direct it into a graduated container. Crank the engine long enough to get 2 ounces of gas in the container and then continue cranking for 15 more strokes of the pump. The pump should have delivered 6 more ounces of gas. Insufficient fuel delivery can be caused by a vacuum leak, plugged flex line, worn pivot in the pump arm, stretched diaphragm, plugged fuel line or tank pickup, plugged tank vent or wrong gas cap or a worn push rod. The push rod should be 8 7/8" long for the cast iron manifolds and 7 7/8" for the aluminum manifolds. It travel is about 3/8". Tom
flatcreeker	-- 12-12-2021 @ 9:46 AM
	Greetings Tom, Why might the pump and or carb exhibit these symptoms only after running for 15 to 25 miles in ambient temps as low a 50F? The surface temps around the carb base and pump base register a max of 150F on my IR gun when I return from a trip to town of about 35 miles. Unsure of the significance but when I get in the Merc after it has sat for a few days, there's a noticeable gasoline odor. There is not what I would consider a significant odor of gas under the hood at such times, nor anywhere around the outside of the car. Doug
TomO	-- 12-13-2021 @ 7:22 AM
	Doug, if there is a vacuum leak in the carburetor, it may only show up as the carburetor warms up. You can check for this by spraying carb cleaner around the base of the carburetor. Pay particular attention to the area where the carburetor body meets the cast iron base. Another area of concern is around the throttle shaft. Concerning the gas odor, you should try to isolate where the odor is coming from. I never get a gasoline odor inside or outside of my 40 Mercury. If the odor is only inside of the car, check the fuel sending unit area to make sure that gas is not leaking there. You may also have rust pinholes in the top of the tank. You should also check the condition of the rubber hose that connects the filler pipe to the tank. I get about 10 years of service from them. A bad distributor rotor can cause a miss like you described, but it usually shows up at a steady speed as well as when accelerating. The fix is to wrap 6the distributor shaft,under the rotor, with shrink tubing or electrical tape. Have you contacted any of the Regional Groups near you? You may be able to get some help from one of the members. Tom
flatcreeker	-- 12-13-2021 @ 7:50 AM
	Tom- I am making a list, a rather long list, of things to ck when I get back to the cabin (and Merc) including the items in your last post. I am sending you a PM on a different matter. Thanks again, Doug

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