Flathead Facts by John w Lawson

[pickup]

Thanks 38 coupe for suggestion the book. I just finished reading Flathead Facts by John W Lawson. A good book but kinda disappointing for what I was trying to find out. He takes an 8BA stock engine and gets it running good with out explanation and then starts making changes to the engine and then checks it on the Dyno and tells what happened.

It is a good read and will surprise most car guys as it did me. My problem is that my 8BA is not running good to start with and until I find the problem there is no use to start taking the information I learned from John and using them on mine.

I think I am getting gas to my carburetor. My experience has been that when the fuel pump goes, it quits period. the engine cranks and runs fine at idle after it warms up a little. IT MAY EVEN RUN AT INTERMEDIATE STREET SPEEDS FOR A WHILE BUT IT MAY SKIP FROM THE TIME U CRANK IT. Either way when u reach 45-50 MPH she starts to buck and jump. Slow to 30 and the pulling gets more consistent but still misses then runs then misses. slow to a stop and it idles fine.

I am new to this truck and it was rebuilt or worked on before I got it and was changed to 12 volts.

John talks briefly about the earlier dual point distributors used on the 59A engines and goes on the say that the stock distributor in the 8BA is marginal because of the single points configuration which does not provide as much coil saturation and the much maligned vacuum advance system. He goes on the talk how the vacuum advance does not work with multi carbs but I wonder if it dependable and OK for a single Holly 94.

I also read that u need a resistor for the 12 volt coil when u install a 12 volt system. I am not familiar with this resistor and wonder where it would look like and be located. My existing coil seemed awful hot the other evening after a trip around the block so I have purchased a new coil with a built in resistor. Question is if there is a resistor already hidden in the system what is going to happen with two resistors?

John goes on to talk about installing a Mallory dual point distributor that did not work any better than the stock Dizzy. A MSD6A control box was installed and still no measurable HP advances over the stock distributor.

I understand that these upgrades to the ignition system helped to make sure other additions to the engine (when they souped it up) worked to there proper specifications but what abour the stock setup, what mwkes it work properly and what needs to be checked to find out why it is not working properly without spending $350.00 for a distributor $40.00 for a coil, 100.00+ for a controller and all this may not solve the problem.

Any thoughts and information will be appreciated and thanks again to 38 coupe for suggesting the book.

[JSeery]

The coil most likely needs a resister, but it depends on the coil. You need to check the resistance of the coil to be sure. There are basically two types of 12V coils, ones that require a resister and ones that don't. The ones that do not require a resister are usually marked as such. It has to do with the total resistance in the circuit, total should be somewhere around 3.0 ohms. So if your coil is 1.5 ohms you need a 1.5 resistance with it, ether built into the wiring or with an add-on resister. If your coil is getting hot it is most likely in need of a resister, with out it you will eventually fry the coil and the points. They can be found at almost any auto parts store, just ask for an ignition/coil/ballast resister. There are different styles, but do the same thing.

[40cpe]

You can check to see if there is a resistor in your wire to the coil by checking the voltage at the terminal of the wire from the ignition switch to the coil. If you have no resistor in the wire the voltage should read very near battery voltage. If you have been running with too much voltage to the coil the points might now be burned, too.

[Mike B]

I don't believe the points care about the voltage...i/e points aren't 6v or 12v specific.

[19Fordy]

This FORD drawing may help. It is Negative ground. The first photo also shows ballast resisitor "J" described earlier. I painted it black with a magic marker. It sounds like what you need to do is "go thru" each component of your electrical and fuel system to find out if each is functioning properly. Is the starting system wiring hooked up correctly? Do you have spark at ALL your plugs? Are your plugs fouled? Do you have spark at the points? Are your plug wires and coil wire good? Is your firing order correct? Is your vacuum advance working properly? Is you coil resistor or coil with internal resistor wired up correctly. Is your fuel pump "pumping"? Is gas squirting out of the carb jets when you accuate the accelerator pump? Is you coil any good? Is the flexible fuel line on the firewall in good condition (if you have one)? Is your condenser good? Does your carb. need to be rebuilt? Is there rust in you gas tank that could be clogging up your fuel lines? Is your gas filter clogged up? Examine each component in a step-by-step methodical manner so as to determine what is NOT working properly. And finally, send your distributer to Bubba to get it "set right". It is money well spent, rather than buying new expensive parts that confuse the issue more. I am confident you can solve your problem. Just take it one component and step at a time. Do you have a friend who is a "car guy" who might be able to help? Are you a member of any car club whose members may be able to assist you? All the best. I strongly suggest that you have Bubba convert your distributor to and electronic ignition so as to avoid future point and condenser problems. Be sure and talk with him about this as he will provide you with information you may not be aware of. I converted my Mallory dual point to electronic 10 years ago and have been very happy. That is the reason for the green wire you se in the photo. Click on photos to enlarge.

[JSeery]

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Originally Posted by Mike B

I don't believe the points care about the voltage...i/e points aren't 6v or 12v specific.

It's not the voltage, it's the current. Anything much about 3 amps will burn the points. With the resister type of coil you want something in the 6v to 7v range at the (+) coil terminal on a 12V system. But it is the current that is the issue.

[BrianCT]

The original distributor is fine for a stock motor if it is in good condition and properly set up.

[JWL]

It is unfortunate a book could not be written to cover all the possible maladies associated to cars and trucks. If such a book was available we would need a forklift truck to handle it.

If possible, determine whether the problem is internal or external. Usually intermittent misbehavior is external. Next, determine if fuel or ignition related. Often a judicious application of the choke during periods of poor performance will give a hint. If there is no change as the choke is slowly applied it might be better to concentrate, first, on the ignition system. Look for loose-poor connections. Then change the condenser. Look to see if the points are burned-blued-pitted. I don't know what year model your truck is? If newer than 1948 it won't have a resistor unless one has been added. However, even with an extra resistor a quick coil change during a time of engine illness will tell you something. A temporary, separate wire can be installed from the battery directly to the new coil for a test. It is possible the pigtail wire inside the distributor is frayed-insulation worn. A stock distributor in reasonable condition will run great on the stock engine.

It is possible a piece of crud is swimming inside the carb and interfering with jet flow. Or a fuel tank dirt-blockage condition exists. Or the fuel pump is marginal. Or the camshaft pump lobe is worn. Or the pump rod is too short. Or the tank to pump line is fouled. We won't know whether to look at these until other checks are completed.

[corvette8n]

Also be sure you have a good ground to the block and chassis, don't just look at the wires and assume they are ok, disconnect, wire brush, reconnect, learned that the hard way onetime.

[Carbroke]

I think there is some confusion as to resistors when used in the coil circuit.

A ballast resistor is usually bypassed when cranking, but in series with the coil when not cranking. This allows a little hotter spark for starting, but saves the coil from getting hot for long runs. If not switched in/out by ignition switch, the ballast resistor has a thermal capability in that it has a lower resistance when cold and gradually gains resistance (to point) as it warms up due to current flow.

When a 6 v coil is retained after a changeover to 12 v, you need to put a series resistor that equals the 6v coil dc resistance to drop 1/2 of the voltage so that the 6v coil doesn't see too much voltage. Otherwise twice the normal current will be drawn through the coil and it will eventually fail. This would also necessitate a value change for any existing ballast resistor as well. The dropping resistor would be in series with the coil in both phases of cranking or running but the ballast resistor would still be switched in for run mode
and bypassed for cranking mode.

If your car was changed to 12v AND the coil was also changed to a 12v version, you don't need a dropping resistor in the circuit. However it would still be prudent to have a ballast resistor. It's been a while since I messed around with it, but I think the ballast resistor only drops a couple of volts in run mode, so that the coil only sees about 10.5 volts or so.

Keep in mind that in run mode and properly charging, a battery will see around 14.2 volts.

[Bassman/NZ]

John's book was never intended to be a repair manual.... I'm surprised you thought it was. It is undoubtedly the finest book of its kind, and has saved me, and no doubt countless others, a bunch of money. It seems to me you need to spend a lot more time using the search function, both here and the many other fine sites, such as bilben's. All your questions, in fact everything you could wish to know, is available here on the interweb.

[GreenMonster48]

I replied to your other thread, I guess you missed it. I just did a 12V conversion. I used these parts:

Napa Echlin Voltage regulator for 1956 F100
Napa Echlin Coil IC14 (this is an internally resisted coil AND it fits in the original coil holder)

There is no other resistor 'hidden' anywhere that will interfere, providing your truck is stock. Your symptoms sound exactly like a hot coil that needed a resistor, but didn't have one. Check your points again to make sure they aren't burnt.

[Mike51Merc]

Originally Posted by JSeery

It's not the voltage, it's the current. Anything much about 3 amps will burn the points. With the resister type of coil you want something in the 6v to 7v range at the (+) coil terminal on a 12V system. But it is the current that is the issue.

Can you elaborate on this statement?
My understanding of electrical theory differs.

[JSeery]

Not sure what your question is. An ignition system is fairly complicated and to go into detail would be confusing and not be much help to someone attempting to solve an issue on there car. A simple and very incomplete explanation is in a points ignition the points are a switch or trigger that grounds the coil. All of the current is the circuit would pass through the contacts on the points and the arcing would quickly burn them up. The system is designed for maximum output of the coil with minimum arcing across the points. This is controlled by the design of the coil, the addition of a condenser and limiting the current. Current can be controlled by a coil that has the resistance internal, by an external ballast resister or by resistance built into the feed wire to the coil. In an ideal system all of these components are designed to work together. When we start switching parts around you have to do the best you can to approximate the correct conditions in the circuit. For a 1.5 ohm coil a 1.5 ohm ballast resister is about the proper resistance to drop the voltage to the coil into the 6 to 9 volt range (which is what this type of coil is designed for) and help limit the current (along with a lot of other factors) across the point. The goal of all of this is to prolong the life of the coil and the points while providing a health spark to the plugs.

[lesbliss]

We had the same problem with our 51 Merc. After several tows home and lots of time and money spent on carb, fuel pump, and ignition rebuilds we decided that we weren't staying strickly stock anyway so a change to an electric fuel pump, a converted GMC distibutor from Bubba's and a Carter 2 barell carb. off a 70's Ch--- small block solved all the glitches. Car is now my daily driver and always starts,runs strong and parts are easier to get. Oh and NO MORE TOWS.

Les Bliss
51 Merc

[V8COOPMAN]

Originally Posted by lesbliss

.............. and a Carter 2 barell carb. off a 70's Ch--- small block solved all the glitches.

Les Bliss
51 Merc

I wasn't aware that Chevy used CARTER carburetors on '70s small blocks. DD