Carburetor Problems On Older Cars

texases · May 2009

Point gap 0.019", or dwell 28-32 degrees, and 4 BTDC looks ok for timing. Here's a table, same values listed for all v8s. Timing is set after points, because adjusting points changes timing.
chevy tune up specs

crampton1998 · May 2009

I set the point gap to 0.018" and adjusted the timing to 4 BTDC with the vacuum advance disconnected and the port and hole plugged. Now the engine ides fine but I still have a reading of 0Hg on my vacuum gauge until I throttle the engine up manually. When I drive the truck it feels as though the engine is choking itself out, what could cause me to lose vacuum pressure thru the carb when I haven't messed with the carb at all ? I checked my vacuum gauge and it is functioning properly.

texases · May 2009

You reconnected the distributor vacuum, right? Are you sure the vacuum advance diaphram is OK? Are you sure the centrifugal advance mechanism works (does the timing advance when you rev the engine with the vacuum advance disconnected). Where exactly do you have the vacuum gauge attached?

zaken1 · May 2009

The reason you have lost vacuum through the carb is that there is only one manifold vacuum port on the carb: and you are now using that port for the vacuum advance. The other carb port to which you connected the vacuum gauge provides what is called "ported vacuum" That kind of port only supplies vacuum when the throttle is partly open. This kind of port is not suitable for running a vacuum gauge, and should not be used in your application. Some other kinds of engines need it for various purposes; but not yours.

In order to get manifold vacuum to run the gauge; you will either have to install a "T" fitting in the distributor vacuum hose; or connect the gauge to the manifold vacuum spigot on top of the intake manifold beween the carb and the distributor.

Since your motor has a larger cam; the manifold vacuum at idle can be expected to be lower than on a stock engine. And for that same reason; the stock timing specs are not appropriate for your engine. On this engine; I would expect the optimal timing point to be somewhere between 8 and 16 degrees BTDC. If the timing is too far advanced, the idle will become rough or unstable; and/or the engine will ping or knock under heavy throttle. But when you compare two timing settings; if the engine idles just as well, and doesn't ping under acceleration using the more advanced of the two settings, it will probably give better performance and fuel economy with that setting. So the way to find the best timing setting is to keep advancing it in 2 degree increments; until it either becomes rough at idle (and that roughness cannot be smoothed out by adjusting the idle mixture screws) or it either begins pinging under load or losing power at some point in the throttle range. Whenever you set the timing; the idle mixture and possibly the idle speed should then be readjusted to run best at that timing point.

There are two other tests I'd like you to make: one is to hook up a timing light and compare the timing at idle with the vacuum advance hose connected; and with it disconnected. The timing should be advanced much further when the vacuum advance hose is connected. It it doesn't change when the hose is on or off; the vacuum advance unit is defective.

The other test that is still not done is to slide a screwdriver along the cylinder head next to the spark plug hole, and see if there is a shoulder which surrounds the hole at a slightly larger diameter. This will reveal which type of spark plug belongs in that engine; and that can have a big effect on the way the engine runs.

crampton1998 · May 2009

I guess I forgot to post that I checked the spark plug holes and I do have a shoulder. Sorry about that I forgot to post the results after returning from vacation. Now back to the vacuum, it doesn't matter which port on the carb that I hook the gauge up to, they both have the same result, 0Hg at idle and when the engine is revved up it will shoot up to around 15Hg.

zaken1 · May 2009

That means that both ports on the carb supply ported vacuum; and there is apparently no manifold vacuum port on that carb. But the catalog description for that carb states that it has both a manifold vacuum and a ported vacuum port. How many vacuum spigots in total does that carb have? Have you looked on all sides of the carb for additional spigots? I thought you previously said that one of the spigots had vacuum on it at idle. Isn't that why you moved the advance hose to that spigot?

If there is no manifold vacuum port on the carb, you can use the vacuum port on top of the manifold; between the carb and the distributor. And please run the timing light check I suggested, after you find a manifold vacuum port.

The extra black wire from the points that you noticed is a ground wire to electrically bond the points to the distributor body. I'm glad to hear it is still intact. Many people remove that wire, because they don't understand the reason for it being there.

The bogging you previously experienced was most likely the result of the point gap being set to too small a distance (which would make the dwell angle too large). When the point gap is too small; the points will tend to arc at low engine speeds; and that causes misfiring and bogging.

There is a test to determine whether a set of points is bad; which is done by measuring the amount of voltage that is lost through the points. It has been a while since I used a dwell meter; but I believe there is a point test scale on those meters. You can also measure that with a voltmeter set to the lowest DC voltage scale, and connected between ground and the coil "minus" terminal; with the points closed and the key on. The meter should read less than 0.2 volts. If it reads higher than that; the points should be replaced. But make sure the points are closed before you hook up the meter; otherwise if the points are open (on an analog meter) the needle will shoot up and hit the peg.

crampton1998 · May 2009

The reason I moved the vacuum from the port to manifold is because it was suggested by someone in the forum. I had vacuum on Wed of last week before I left on vacation. When I started the engine Monday I had none. I am at school at the moment so I will try to run the timing light test before work this evening. As for the vacuum port in between the carb and the distributor it is being used for the brake booster.

zaken1 · May 2009

Yes, I know someone in the forum suggested that you move the advance hose to the manifold vacuum port; because it was me who told you that.

You may have previously read vacuum at idle from one of the ported vacuum spigots; if you had made the check when the engine was cold and the choke was on. When the choke is on, there is a fast idle cam which holds the throttle open a little further than normal, and that much added throttle opening would make some vacuum come from the ported vacuum spigot.

If there is no other manifold vacuum source available, you'll just have to add a plastic vacuum "T" in the vacuum advance hose. If you don't intend to use it all the time, you can put a rubber cap over the fitting when it is not in use. But you really should run the timing light test BEFORE you do this; because if the vacuum advance diaphragm is leaking; it will cause your vacuum gauge to read lower than the vacuum really is.

crampton1998 · May 2009

Still at school, I will try to get the timing light test done before I go to work this evening.

crampton1998 · May 2009

The vacuum gauge had debris in the hose. LOL. Engine had a hard time starting tonight, re-set points and engine is running like a dream except for the bog in between 40-50 mph. The engine is purring and runs better than it ever has since I bought it. Vacuum pressure is holding steady at 14-16 Hg with the timing somewhere around 12 BTDC, and I have the stiffest return springs in the carb. What should I check now guys ?

crampton1998 · May 2009

I also did the timing light check on the vacuum advance as suggested before. With vacuum disconnected timing was around 12 BTDC after hooking up vacuum advance timing was advanced well beyond the timing bracket.

crampton1998 · May 2009

Just swapped metering rods and springs. Springs are blue and are 3-inch Hg while the metering rods are Part # 7047. This change created alot more low end power but didn't fix the bogging problem in between 40-50 mph. Should I try the largest metering rods part # 7547 and different springs or is it just probable that my problem lies elsewhere ?

crampton1998 · May 2009

Zaken1 you still there ?

zaken1 · May 2009

You wrote earlier that the bogging was cured. I believe this was when you first adjusted the points. If you had starting problems after that, and had to readjust the points; it sounds like the point gap changed. This should not happen under normal conditions. The point gap will only change if 1> the two mounting screws for the point assembly are not tightened, or 2> the distributor cam is not adequately lubricated.

The arm for the movable point has a fiber rubbing block in the middle, which rubs on the distributor cam. This block will wear down rapidly, if it is not coated with distributor cam lubricant (which you can buy at auto parts stores). The rubbing block should be lubricated whenever the points are replaced.

The two screws that hold the point assebly in place should be tight. They do not need to be loosened when you adjust the point gap. The proper way to adjust the point gap is by turning the allen screw that is in the point assembly. The allen screw is spring loaded; which enables point gap adjustments to be made without loosening any lock screws.

It is nearly impossible to properly set the point gap in a Delco Remy distributor with a feeler gauge. The rotor and centrifugal advance mechanism block the points from being seen; and also make it very difficult to hold the gauge so that it is not tilted with respect to the points. It is also extremely difficult to turn the engine so that the rubbing block is really on the highest point of the distributor cam. So the actual point gap usually ends up being wider than what you tried to set it to. Besides that; the specified point gap is much larger than the gap ends up being when you set it with a dwell meter. The point gap, when set with a dwell meter to exactly 30 degrees, will probably be about .012". And that makes a great big difference in the running quality.

For those reasons; I highly recommend that you buy a dwell meter. When you have a dwell meter; you'll be able to check and set the point gap while the engine is running, by inserting an allen wrench through the window in the cap. It is easy to set the dwell exactly to the manufacturer's specs. And once you've seen how easy it is to adjust the point gap by that means; you'll probably never want to set it with a feeler gauge again!!!

It sounds like you were reading this post at the same time that I edited it.

I would not recommend trying to dial in the carb until you have set the point gap properly (which I doubt it now is); and have found the best timing setting, and have adjusted the idle mixture screws.

I would also suggest; when making changes in the carb metering, that you do NOT make more than one change at a time. IE; don't change both the rods and springs in the same operation. The effects of one can interfere with the other. Just change one of those parts; and see whether it makes things better or worse. If it makes things better, then keep it and try changing the other item. But if it makes things worse; go back to the previous setting, and then try changing the other item. In general; the springs will have a greater effect on low end performance; while the rods will have more of an effect on mid range and top end.

crampton1998 · May 2009

The rubbing block was greased with that which was provided in the box when purchased new. The points were extremely in-accesible at first and I had to remove the capacitor to access the points with a feeler gauge. The bog was "cured" when I adjusted the original points according to the highest RPM's by ear but I had lost alot of my bottom end power. I will try to locate a dwell meter as none of the local auto parts chains have one in stock and use it to set the points. Thanks again for your suggestions.

zaken1 · May 2009

I found you a dwell meter; which is fairly priced and has some useful extra features:
http://www.amazon.com/Actron-CP7605-Tachometer-Voltmeter-Analyzer/dp/B00062YUUS

I also wanted to mention that your observation about the bogging clearing up when the point gap was adjusted for maximum engine RPM (which undoubtedly was a very wide point gap) indicates that the ignition coil may not have a ballast resistor connected to it. Breaker point ignition circuits are designed to be used in series with a resistor connected between the coil and the battery power wire. This resistor is intended to limit the current drawn through the coil to a level which does not produce excessive arcing across the points. If that resistor is not wired into the circuit; the engine will still run, but it will stumble and miss under load at low engine speeds.

The ballast resistor is usually a ceramic block; which looks like the one in the following link:
http://198.208.187.182/internet/PartImage.jsp?&acpartnbr=C1101

but Ford pickups from the 1960s used a resistance wire instead of a block resistor, which looks like this:

http://info.rockauto.com/SMP/SMPDetail3.html?RW34.html

Your truck should have one of these two types of resistor on it. If it doesn't, as I suspect is the case; I recommend that you buy the block resistor pictured in the first link; which is intended for a 1969 Chrysler Newport, with the 383ci V-8 motor. That type of resistor would be the most appropriate match for the Accel coil you have. You can mount it on the firewall, or on the engine close to the coil. You'll need to get a length of 16 gauge stranded wire that is long enough to run from the resistor to the coil, and crimp a ring terminal on each end of the wire. (a wire terminal crimping tool is a great thing to have in your toolbox; and they are very inexpensive.) Take the power wire off the coil's plus terminal, and connect it to one terminal on the resistor (using the screws that come with the resistor). Connect one end of the new wire to the other terminal on the resistor, and connect the other end of the new wire to the plus terminal on the coil.

If the motor becomes too hard to start after the resistor is installed; it will be necessary to add a relay which bypasses the resistor during starting. But the Chrysler resistor may work OK without adding such a relay.

crampton1998 · May 2009

I found and purchased a dwell meter. Checked the dwell and it was at 28 adjusted it to 30 and reset the timing which didn't change much if at all. Adjusted the idle air screws and went for a test drive. Engine died when put in reverse and I re-installed the original metering rods and springs. Metering rods are stamped with part # 1451 and the specs are 070 x .047 with the return springs being the orange ones which are 5-in Hg.

crampton1998 · May 2009

Changed metering rods out to 0.68 x 0.52 and drove the truck, still bogging. Just to make sure we are on the same page here are the exact symptoms. When I begin to test drive the truck it runs great if I rapidly accelerate up to 50+ mph everything is great and the truck runs great, when i let off the throttle and drop anywhere below 50 mph I lose all acceleration and it feels almost like the engine is choking itself out. If I floor the throttle I can then accelerate right thru this trouble area.

zaken1 · May 2009

I would strongly suggest re-reading what I wrote about adding a ballast resistor (in post #320); and addressing that point BEFORE trying to fine tune the carburetion. From the way your engine runs; I firmly believe there is no ballast resistor in the ignition circuit. Running without a ballast resistor will make the points arc severely at low speeds; and that is what is causing your bogging. If this is the problem; it will never be fixed by fooling around with the carburetion. And that's why I feel so strongly about adding a ballast before you do any further tuning.

The idle mixture cannot be properly adjusted if the truck has not been driven immediately before making the adjustment. Just warming the engine up without driving it will not work. When the truck is driven a few miles; the fuel puddling in the manifold will dry out, and the plugs will clean up. Only then will it be possible to make a mixture adjustment that will be stable. The best way to adjust the mixture is to come back from driving somewhere, and immediately adjust the mixture without shutting the engine off. That way, the spark plug and cooling system temperatures will be at their normal operating level.

If the engine died when you put it in reverse; that was because the idle mixture screws (they are not air screws; they are fuel screws) were set too lean (too far clockwise). Because those mixture screws are fuel screws; the mixture becomes leaner when you turn those screws inward (clockwise); and becomes richer when you turn the screws out (counterclockwise). The fuel mixture when the engine idles is entirely controlled by the mixture screws. The engine's performance at idle will NOT be changed by doing anything with the metering rods or springs. So, in order to keep things simple and thus make this situation easier to track and understand: I recommend putting the previous set of rods and springs back in; and then just adjusting the idle mixture screws richer. After the ballast resistor is in place; and the idle mixture is set right; you can consider the wisdom of making changes to the rods or springs.

The way to richen up the mixture is to turn both mixture screws counterclockwise, alternately turning each screw in 1/2 turn steps; until you get the best combination of idle speed and smoothness. If you don't notice much difference when you turn the screws; keep turning them further in the same direction. You'll eventually see a change in speed or smoothness; either for the better, or for worse. The goal is to get the highest speed; without it running rougher. One techinque for zeroing in on the sweet spot is to quickly turn both screws a half turn counterclockwise, note the way the engine runs; and then quickly turn the screws back to your starting point; and then turn them a half turn more clockwise. Compare the way the engine runs at those two settings; and it will give you a sense of the direction the screws should be turned to make it run better. When you stop gaining speed or smoothness by turning the screws further; you can make a fine adjustment by turning the screws a smaller amount in each direction, and comparing the results; until you find the best setting. Both mixture screws should always be the same number of turns out from closed. If the idle speed increases when you turn the mixture screws; you'll need to reset the idle speed screw, in order to be able to continue to adjust the mixture screws properly. DONT TRY TO SET THE MIXTURE AS LEAN AS POSSIBLE. This is a modified engine; and engines which have been modified tend to run best when they are set a little on the rich side.

crampton1998 · May 2009

There is a ballast resistor on the firewall. I set the idle at 800 rpm's and the screws at 2 1/2 turns out, turned them counter clockwise until I reached the highest rpm's and then reset the idle at 850 rpm' s. I did all of this before I went for a test drive though. Final setting on the screws was 6 complete 360 degree revolutions. I will go for a test drive and then re-adjust the screws.

zaken1 · May 2009

Are you sure the resistor on the firewall is connected to the coil? There is another resistor that looks just like the ballast which is used for the slow speed in the electric wiper motor.

crampton1998 · May 2009

I will double check to make sure.

crampton1998 · May 2009

Ballast resistor does go to the coil.

crampton1998 · May 2009

Went for a drive and set the fuel mixture screws to highest rpm' s. After letting engine idle for about 30 minutes it began to run rough as if it wanted to die out. I checked the dwell and it was reading around 25 so I re-adjusted the dwell and reset the timing, while adjusting the dwell I decided to check the voltage coming from the coil and it was reading a little under 6 volts so I turned on my headlights and one turn signal and I could notice a dramatic difference in the idle and when I turned the heater fan on high the engine finally died out. Repeated the process minus turning the fan on and read the voltage and it was slightly above 4 volts. The terminals on the ballast resistor are loose and move around freely, is this normal or does it need to be replaced ?

zaken1 · May 2009

That was a great bit of creative diagnostic insight!!! There should be at least 10 volts at the coil at idle, and it should increase to about 12 volts when the engine is speeded up; but it still is unknown where the voltage is being lost. It could be caused by anything from a bad alternator or voltage regulator; or a dead cell in the battery, to a bad ignition switch, or a bad ballast resistor.

The way to sort this out is to start at the source: Measure the voltage across the battery terminals when the engine is off, and no electrical accessories are running. If the battery has 3 cell filler caps; it is a 6 volt battery. So the resting battery voltage should be about 6.2 volts. In that case; there should NOT be a ballast resistor connected to the coil.

If there are 6 cell filler caps on the battery; it is a 12 volt battery, and the resting battery voltage should be at least 12.4 volts. If it is less than 12 volts; the battery is either defective, or is not being properly charged by the alternator and voltage regulator.

Now start the engine, run it at about 2000 RPM for two or three minutes, and then let it idle and measure the voltage across the battery. The voltage across the battery should now be about 14 volts. (Incidentally; is there an alternator or a DC generator on that car? You can see photos of those items on Rock Auto's website. Look up a 1962 Chevy Impala to see a DC generator; and look up a 1968 Chevy Impala to see an alternator.) But if the truck has a DC generator; the battery voltage at idle will probably not be much different than it is when the engine is off. However, it should increase to about 14 volts when the engine speed is over about 1800 RPM. And if your truck has a 6 volt electrical system; the voltage in these measurements should be half of what it is with a 12 volt system. If the voltage in these tests comes out more than 1 volt below the numbers I gave you; there is a problem in the battery or charging system.

Now keep the negative meter lead connected to the battery ground terminal, and move the positive lead to the ballast resistor terminal which is not connected to the coil. With the engine idling, measure the voltage on the meter. The voltage at that side of the ballast resistor should be within 1 volt of the battery voltage when the engine is idling. If the voltage difference is more than 1 volt below the battery voltage; there is a problem with the ignition switch or the connecting wiring.

Now move the positive meter lead to the ballast resistor terminal which is connected to the coil. With the engine idling, the voltage at that terminal should be at least 10 volts; and it should increase to about 12 volts when the engine speed goes over 2000 RPM. If the voltage on the other side of the ballast resistor is good; but the voltage on the coil side of the resistor is low; or if the voltage changes greatly when the terminals are moved or wiggled; the ballast resistor should be replaced. If you replace the ballast resistor; be sure to get one for a Chrysler, and not for a Chevy or Ford. Chrysler resistors have a different amount of resistance; and their resistance changes with temperature. Chevy and Ford resistors have too much resistance for your application. The terminals on some Chrysler resistors will move around slightly; but they are made to do that. As long as the voltage remains constant; a little movement of the terminals is OK. But any screws used to hold the wires in contact must be tight.

Because these parts are becoming rare; some cheap manufacturers have begun using one resistor for all applications. Those are not the ones to get; so check the part numbers for a Ford, Chevy, and Chrysler resistor for a car made in the late 1960s. If the numbers are all the same; do not buy that brand of resistor. Rock Auto still sells the right resistors. NAPA parts stores probably do, too.

One other vitally important point: The battery ground cable should be connected to an unpainted bolt that threads directly into the engine. Some people attach the gound cable to a painted bracket which connects to the engine through two or three other parts. That kind of ground connection can create all sorts of intermittent problems. There should also be a second ground wire which goes from an engine bolt (Chevys often use one of the valve cover bolts) to a bolt on the firewall. That wire can be smaller in diameter than the battery cable; or it might be a braided metal strap. On some cars; there is a second ground wire from the battery negative terminal to the body. But if there is no such auxiliary ground wire bonding the engine to the body; you must install one. That wire will clear up many mysterious electrical problems.

I'm going to be away from the computer for the rest of the day; but I hope to check back in this evening (unless my car breaks down).

crampton1998 · May 2009

Ran the test that you recommended and here are the results. 12.4 volts not running, 14.35 volts after 2000 rpm's, 11 volts at terminal not connected to coil, 8 volts at coil wire connector. According to what you posted earlier I will assume my next step is to buy a new ballast resistor ? I will purchase one for a 1969 Chrysler Newport, with the 383ci V-8 motor like you stated earlier.

zaken1 · May 2009

Good information, but you missed something: The voltage at the ballast terminal which is not connected to the coil should be within 1 volt of the voltage at the battery. But in your truck; the voltage at the ballast terminal which is not connected to the coil is 3.35 volts lower than the battery voltage. This sounds to me like there is a resistance wire between the ignition switch and the resistor (like the one in the link I sent in the post about ballasts); and someone didn't realize that this resistor was already on the truck and installed the ballast resistor is series with the resistance wire that was already there. So you in effect have TWO ballast resistors in series on that truck. What you need to do is to remove that ballast resistor, and securely connect its two wires together. This will leave just one resistor on the truck. If the wire at the battery side of the resistor is long enough to reach the coil; just move it to the coil and discard the wire that went from the low side of the resistor to the coil. But if the wire is not long enough to reach; you could cut and strip the ends of the two wires and solder them together; or connect them with an inline splice connector; or use a screw to fasten the two terminals to each other. But any bare metal at the connection must be securely covered with electrical tape, to prevent it from touching a grounded object and shorting out the wiring.

If there definitely is not a resistance wire between the ignition switch and the ballast; then the ignition switch has developed excessive resistance; and should be replaced. But whatever the case; don't buy another ballast resistor!!!

crampton1998 · May 2009

I will remove the resistor in the morning and see how it goes. as for the ignition switch, I just replaced it a couple weeks after I bought the vehicle due to the fact it was getting hard to insert, remove and turn key.

crampton1998 · May 2009

Removed the ballast resistor and hooked the power wire straight up to the coil instead of splicing it. I now have 11 volts going to this terminal on the coil, but on the other terminal which goes to the distributor I have only 8 volts. When the lights, signals and fan are turned on it still drops. When the first two are turned on the voltage "bounces" between 12-14 volts until the fan is turned on then the engine wants to die out. Voltage at idle is 14.20-14.40 volts. I have one ground coming off the battery and it is going to the alternator bracket that is painted.

zaken1 · May 2009

OK; since there are some known bad issues (the ground cable not going directly to the engine; and there not being an auxiliary ground wire from the engine to the firewall); move the ground cable to an unpainted bolt that goes directly into the engine (buy a longer ground cable if you have to, in order to make it reach) and buy a length of 12 or 14 gauge wire that is more than long enough to reach from the engine to the firewall; buy some ring terminals to crimp on the ends of that wire and a crimping tool to use on the terminals, and install the battery cable in the right place, and the auxiliary ground where it is supposed to be. Then run your voltage drop test again.

crampton1998 · May 2009

Hooked up ground wires and nothing has changed, around 11V at + terminal on coil and 8V on distributor terminal and when I turn on the accessories the engine idles rough and still wants to die out. If I have 11V at one terminal and 8V at the other does this mean that the coil could be bad ?

crampton1998 · May 2009

I decided to run a jump wire straight from the + battery terminal to the + coil terminal. I ended up with 14.25 volts @ the + coil terminal and 8 volts at the distributor terminal. I am going to test the voltage at the ignition switch next and post the results.

crampton1998 · May 2009

I only have one terminal coming off of the back of the ignition switch and it has a red wire going to it, this wire has a connection in the middle of it that is similar to the resistor wire that was in the picture that you posted a link to earlier, 14V at it when tested, I imagine this is the + wire coming from the battery ? I have2 red wires, a yellow and black wire on the switch, which one goes to the coil ? The ballast resistor is off of the engine. I was trying to figure out which wire went directly to the coil so I could run a wire straight to the coil from the switch and eliminate any electrical connections between the switch and the coil before purchasing a new switch.

I figured out which red wire went to the coil and jumped it with some of the 16 gauge wire I purchased. Voltage was 13V into the coil and 7V out of the coil and into the distributor.

crampton1998 · June 2009

Tested the ohms going thru the coil and it read 0.00, from what I could gather from the internet this means the coil is good, ran the same test on the restricted wire off of the ignition switch and it read 0.00. So correct me if I am wrong but the restricted wire and the coil are both reading 0.00 with the key in the off position and when running the coil is measuring around 3.55 ohms which they say is about right. What should my voltage be coming out of the coil and into the distributor ? Another website stated that I should have 11-12V going into it and around 6V coming out of it.

zaken1 · June 2009

First of all; it sounds like you are not using your ohmmeter correctly. In order to properly use the meter; it is necessary to understand the difference between volts and ohms. Voltage is the amount of electrical pressure coming from a battery, an electrical outlet, or any other object that has electric power in it. There are two kinds of electricity that produce voltage: One is called direct current (DC). DC electric current (typically from a battery) always flows in one direction; which is conventionally described as flowing from negative to positive. The other kind of electricity is called alternating current (AC). AC current typically comes from a household electrical outlet. AC power reverses its direction many times a second. There are two different settings on a meter to measure voltage. One setting is for AC volts; and the other setting is for DC volts. Most automotive voltage measurements will be in DC volts.

There is a third type of meter setting, caled ohms, used to measure resistance. Ohms is the amount of resistance to electrical flow of an object that does NOT have electric power in it. The ohmmeter has a battery in it. When you set the meter to measure resistance; the meter battery is connected to the probes; and the current from that battery flows through the probes, through the object you touch the probes to, and back to the meter and the meter battery. It is not possible to measure the resistance of something that has electric power in it; because the electricity will interfere with the power flowing from the meter battery. You can damage a meter or blow out the meter fuse by trying to measure the resistance of an electrically live circuit.

When you turn the function switch to "volts" the meter battery is not used; and the meter just reads whatever amount of voltage is applied to the probes. But in order to measure resistance, the function switch must be turned to the"ohms" position. In that position, the meter battery is connected through the meter and the probes. When the meter switch is set to the ohms scale; if you touch the two probes together; the meter should read zero ohms (because it is measuring the resistance of the probes and their wires; which is effectively zero). But when the probes do not touch each other, the meter should read "infinity," because there is an infinite amount of resistance through objects which do not conduct electricity, such as air, wood, plastic, glass, paper etc. But if you touch the probes to the two ends of a resistor; the meter should read the amount of resistance in that resistor. The only thing that will read zero ohms is a plain piece of wire or a metal bar.

Since the meter read zero when you tried to measure the resistor wire; and also read zero when you measured the coil resistance; is sounds to me like the meter switch was not set to measure resistance; but was instead set to measure voltage. There would be no voltage through the coil when the key was off; and no voltage through the resistance wire either; so the meter would read zero if it was set to measure voltage. But if you set the meter to measure resistance; it should have read about 1.4 ohms across the two small terminals for the coil primary winding, and about 9,200 ohms between either of the small terminals and the metal contact in the center tower for the coil wire. I'm not sure about the exact reading for the resistance wire; but it should have been somewhere between 1.3 ohms and 3.5 ohms.

One other problem could have been that; if you tried to measure the resistance of the coil while the distributor and ignition switch wires were still connected to it; since the distributor is connected to ground when the points are closed; and the ignition switch is connected to ground when the key is off; if the meter was set correctly to measure resistance, the current from the meter battery would have detoured through the ground loop and not measured the coil or wire resistance at all; and that's why the meter read zero. In order to accurately measure the resistance of a part; it should not be connected to anything else at the time!!! And, as I said before; it also should not have any external power flowing through it.

The voltage reading you previously reported through the resistance wire (11 volts while the engine was running) is a normal reading. The voltage at the low side of the coil (between the coil and the distributor) cannot be accurately measured while the engine is running; because it changes so rapidly that the meter cannot follow it. However, you can measure the voltage at that point when the engine is stopped and the key is on (with the points closed). It should be somewhere between 6 and 8 volts. If the points are open when you make that test; you will read the same voltage on both sides of the coil (probably about 12 volts).

Did you fix the battery cable and auxiliary ground wire? If so; did that make a difference in the stalling and the steadiness of the voltage readings? Your dwell readings should not keep changing. One thing that could make it change is poor ground connections. Another thing that could make it change is loose bushings for the distributor shaft. If you grasp the rotor and try to push it from side to side; there should be no side play in the shaft. It you can feel it flop from side to side; the bushings are probably worn out. That would prevent the dwell from staying where you set it. In that case, it would be time to get a new distributor. And if you did that; it would be wise to get one with a breakerless electronic ignition system installed in it. Then the ignition system would have a lot more power; you would not need a resistance wire, and there would be no more points to ever adjust or change again. If you decide to do this, I can suggest the best sources and brands for these parts.

zaken1 · June 2009

I apparently wasn't thinking clearly when I wrote that the voltage between the distributor and coil (going out of the coil) should be between 6 and 8 volts when the engine is stopped with key on and the points closed. If your meter is connected with one lead grounded to the ENGINE, and the other lead connected to the coil minus terminal (the terminal where the distributor wire connects), the voltage at the coil minus termnal should be no more than a few tenths of a volt. The only voltage you should see in that test is the voltage which is dropped across the points. And a set of points in good condition should drop between 0.1 and 0.25 volts. Anything higher than that indicates either that the distributor is poorly grounded to the engine; or that the points are shot; or that the points are open and the capacitor is shorted. Of course; if the points are open when the engine is stopped; you will see full battery voltage in that test.

If the meter is grounded to the battery POSITIVE terminal; you should see close to 12 volts at the low side of the coil, but if you get a reading of just a few volts at the low side of the coil; try moving the ground lead to the engine block. If you now get a much lower reading than you did when the meter lead was grounded to the battery hot side; there is excessive resistance or a bad connection in the battery ground cable.

After you get through the ignition switch, the resistance wire, and to the coil; all the remaining battery voltage should then be dropped across the coil winding (except for the few tenths of a volt which are dropped across the points).

crampton1998 · June 2009

Went outside and tried to start the truck, Had an extremely "hard start" sounded. Engine still had the "hard start" but started on the second crank and ran with a rough idle. Killed the engine and static timed it. Went to start the engine and had the hard start but wouldn't start, next turn didn't crank just clicked and whined, now when I crank the engine it just clicks and whines with no start whatsoever. Did the starter overheat. Oh yeah, no voltage to the coil at all with the key in the run position.

zaken1 · June 2009

It sounds like either the ignition switch has gone out, or the battery has worn out or become discharged. Did you take the ground cable off the bracket and connect it to the engine??? Did you install an auxiliary ground cable from the engine to the firewall???

You can find out whether the problem is the battery or the ignition switch; by connecting the voltmeter across the battery terminals and reading the voltage. Then turn the headlights on to high beam and, while the headlights are on; read the battery voltage again. If the battery voltage with the headlights on is less than 11.5 volts; the battery is either worn out or discharged. If it is less than 9 volts; there is no way the truck can start without recharging the battery with a battery charger, or jump starting it from another vehicle.

If the battery voltage is more than 12 volts while the headlights are on; the ignition switch has gone out, and that switch will have to be replaced before the truck will run again.

If you jump start the truck; it is essential to connect the cable from the negative terminal on one battery; to the negative terminal on the other battery; and from the positive on one battery to the positive on the other battery. If you reverse the connections; it can immediately destroy the alternator!!! Don't use the color of the cables that are on a vehicle to indicate whether a cable is negative or positive. Sometimes someone installs a red cable on the negative terminal; and other times they may install a red cable on the positive. The only sure way to identify the polarity of a battery terminal is to find the plus or minus marks on the battery case.

Also; the battery must NEVER be disconnected while the engine is running. Doing so can instantly destroy the alternator; just like reversing the jumper cables can do.

If the battery is worn out; it will not be able to be recharged. And even if the engine starts with jumper cables; the battery will not charge up when you drive it. So it still will not crank the next time you try to start it. In that case; the battery will have to be replaced.

If the battery is not worn out and you jump start the truck; the battery will now still be discharged. Because the battery is still discharged; the truck will then have to be run at over 2000 RPM for at least 1/2 hour (and preferably one hour or longer), without shutting the engine off; before the battery will be charged enough by the alternator to be able to restart the engine. If the truck stalls during that time; you may get stuck in traffic or on the road somewhere, and not be able to restart it. That's why it is safer to charge the battery with a battery charger; or by running the jumper vehicle for a half hour with jumper cables connected; before trying to drive somewhere.

After the truck is started and has been running at 2000 rpm or higher for more than 5 minutes without jumper cables; connect the voltmeter across the battery, and confirm that there is at least 13.5 volts at the battery with the engine running. If the battery voltage is now less than 13 volts; either the alternator or the battery are defective. The way to sort that one out is to charge the battery from another source, and then measure the battery voltage; if it has at least 12.4 volts with the charger disconnected, after charging for 10 or more hours; the battery is good. In that case; put the battery back in the vehicle, start the engine, and again measure the battery voltage with the engine running at 2000 rpm. If it still is less than 13.5 volts; the alternator is defective.

crampton1998 · June 2009

12.4V across the battery & 12.1 w/ headlights on.

zaken1 · June 2009

Then either the ignition switch, or possibly the resistance wire, has gone out. If you can find where the resistance wire connects to the ignition switch; and check the voltage at that point, you'll see whether there is good voltage at that point (with the key in the "run" position). Be sure to use a good ground connection for the meter when you are inside the passenger compartment. One of the most reliable places to get a ground is the bolts which fasten the bracket across the bottom of the steering column. If the voltage at the output side of the ignition switch is good when the key is on, and there is no voltage at the coil; that would mean the resistance wire is bad. If that were the case; you could just run a length of 12 or 14 gauge regular stranded wire from the ignition switch to the firewall, and just use the ballast resistor on the firewall instead of the resistance wire. Or you could buy a new ballast for a 1969 Chrysler Newport 383 and use that to replace the ballast on the firewall.

If the voltage at the output terminal of the ignition switch is bad when the key is on; you can confirm that the switch is bad by checking the voltage at the input side of that switch; where the battery wire comes in. The battery power wire to the ignition switch is heavier than the other wires; and is often red. There should be good voltage at the battery side of the switch; both when the key is off, and when it is on. If there is low or no voltage at the battery side of the switch; that would mean that the problem is not in the switch; but is somewhere between the battery cable clamp at the battery terminal, and the switch. Since the headlights work; the battery cable clamp is probably OK; but there might be a loose connection where the battery wire goes through the firewall, or a loose nut where the battery wire connects to the ignition switch. Some vehicles use a fusible link to carry the battery power to the ignition switch. A fusible link looks much like a regular battery cable; but it is designed to burn out internally, like a fuse; if too much power is drawn through it. Fusible links often have a label or distinguishing marking on them. If there is voltage at one end of a cable, but no voltage at the other end; that cable is probably a burned out fusible link; and should be replaced with a new fusible link. Bring the cable to the parts store so they can match it.

crampton1998 · June 2009

The resistance wire should be the wire going to the coil and the red wire on the only terminal at the switch should probably be the power/battery wire, correct ?

zaken1 · June 2009

Yes, it sounds like that is correct.

crampton1998 · June 2009

I'm sure glad you are probably sitting down for this one. Removed the battery ground, found loose + wire on starter and tightened it, tried to start engine, wouldn't start just heard one click and then nothing, tried once more and nothing not even a click, removed ignition key, talking to neighbor while standing next to driver's door and heard click,click, click like the engine was trying to start. Sounds like a short in the ignition switch to me ?

zaken1 · June 2009

That is the most likely explanation. Glad I was sitting down...

crampton1998 · June 2009

Just trying to add some humor to a frustrating situation. Swapped out the ignition switch and fixed the clicking problem without the keys but engine still won't start just clicks when turned to start position. I have proper voltage going into and out of the brand new starter solenoid.

zaken1 · June 2009

If you have proper voltage as described; the brushes in the starter motor have probably worn down to the point where they've stopped making contact with the armature. So you need to exchange the starter motor for a remanufactured unit. There are lots of cheaply rebuilt starters and alternators out there; which often need to be returned as soon as they are installed. My experience has been that NAPA stores sell the best quality rebuilt starters. They are each individually tested, and come with a printout of the test results for the actual unit you buy.

Some Chevys have thin metal shims under the starter; which are used to adjust the position of the starter with respect to the ring gear on the flywheel. If the starter on your car has shims between it and the engine; they should be reinstalled under the replacement starter.

zaken1 · June 2009

I thought you'd like to know that I found out a little more about the year of your engine. The Chevy 350 was only made with gasket type plugs until 1970, so combining that information with the results of Mr. Shiftright's engine number research determines that; if this engine was originally from a passenger car, it was made between 1968 & 1970. If this engine was originally from a truck; it was made between 1969 & 1970. That can be helpful to know when you buy certain parts.

crampton1998 · June 2009

Thanks for the engine info, getting ready to pull starter in a few minutes.

crampton1998 · June 2009

Pulled the starter and took it to an Advanced Auto Parts store to get tested. Tested fine and worked perfect for them. I not only have a fender mounted starter solenoid but also a starter mounted. I went next door to an Auto Zone to see if they had a new one in stock that I could look at because I have a wire that is "jumped" from the battery cable terminal on the starter to the R terminal. The salesman asked to test the starter because of the difference in the machines used, and I obliged him. He first tested it without the R wire hooked up and nothing happened, second test had the R wire hooked up and it sparked and melted right thru his wire. Use this link to access the enlarged image of the starter to see the wire on a stock starter that is hooked up to the battery on my starter.

http://www.autozone.com/autozone/catalog/parts/partsProduct.jsp?itemIdentifier=9- 1140_100943_0_&skuDescription=Duralast+/+Starter&brandName=Duralast&displayName=- Starter&categoryNValue=&sortType=&store=503&isSearchByPartNumber=&fromWhere=&fro- mString=&itemId=prod61198&navValue=15300045&filterByKeyWord=&productId=91140&app- QuestionText=&searchText=&categoryDisplayName=External+Engine&parentId=cat30063&- questions=%5B%5D

I went home and bypassed the fender solenoid to no avail and tried to start it while hooked up the original way with both solenoids while the starter was off the engine. I had to run a ground from the starter since it wasn't mounted on the engine. Both tests came with the same result, starter gear comes out and then clicks once. Should I remove the "jumper" and test again?? Am i going in the right direction or should I focus elsewhere ?

bartlem · June 2009

Just put new worked L28 motor in my Nissan Patrol, trying to connect Weber Carby from an XF ford? Having problems working the hoses out and the wiring. Any help would be appreciated.
Cheers

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