Replacing the electronic ignition with points - 1977 400 4V

Also no real set timing really goes by what curve the distributor has in it for that setup. Also if your ant EMP the alternator goes and a generator is needed.

HALIFAXHOPS said:

Also no real set timing really goes by what curve the distributor has in it for that setup. Also if your ant EMP the alternator goes and a generator is needed.

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I'm not anti EMP. I was just looking to have a car that would start and run. Do you see any foreseeable issues with running the points distributor? Is 9 volts too high of a voltage for the coil? Do I need to change the ballast?

Any other systems I need to worry about because I changed to a point distributor?

I like points a good set will give you 10K of driving. Voltage to the coil is controlled by the ballast resistor. For points you want .05/.6 ohms. That is with a 1.5 ohm coil. It will run fine with the other systems on the car.

HALIFAXHOPS said:

I like points a good set will give you 10K of driving. Voltage to the coil is controlled by the ballast resistor. For points you want .05/.6 ohms. That is with a 1.5 ohm coil. It will run fine with the other systems on the car.

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Sarge, would you mind explaining that in more straightforward terms?

I have a 1.5 ballast and a stock coil (compatible with a lot of makes over many years). The distributor and coil that I installed are compatible with 1972 400.

9 + volts at the coil is acceptable?

Blue Brick said:

Sarge, would you mind explaining that in more straightforward terms?

I have a 1.5 ballast and a stock coil (compatible with a lot of makes over many years). The distributor and coil that I installed are compatible with 1972 400.

9 + volts at the coil is acceptable?

Click to expand...

when in start position, full battery voltage will be applied. In the run position, the circuit to the coil is through the ballast resistor and will probably be 7–9 volts if things are in good working order.

Blue Brick said:

Sarge, would you mind explaining that in more straightforward terms?

I have a 1.5 ballast and a stock coil (compatible with a lot of makes over many years). The distributor and coil that I installed are compatible with 1972 400.

9 + volts at the coil is acceptable?

Click to expand...

Should have saie the ballast for points .5=.6 and the primary resistance of the coil 1.5 ohms.

Paul, dont go the .020 deck clearance and .040 HG. You are inviting detonation. Instead go for zero or +.005 deck and the .040 HG. Then if you need to lose some compression enlarge valve reliefs or combustion chamber. Maintaining a quench distance of .035 is very important to combat deterioration.

HALIFAXHOPS said:

Should have saie the ballast for points .5=.6 and the primary resistance of the coil 1.5 ohms.

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1.5 ohms Coil

RU11 seems to meet your recommended specifications:
Cold Resistance:0.5-0.6 ohms
Operating Resistance:1.75 ohms

Is a reading of over 9 volts on the positive terminal on the coil anything to be concerned about?

Since I most likely do not have the correct ballast resistor, will the voltage to the coil change when I buy the new (RU11) ballast resistor?

Depends on what is in there now.

Blue Brick said:

1.5 ohms Coil

RU11 seems to meet your recommended specifications:
Cold Resistance:0.5-0.6 ohms
Operating Resistance:1.75 ohms

Is a reading of over 9 volts on the positive terminal on the coil anything to be concerned about?

Since I most likely do not have the correct ballast resistor, will the voltage to the coil change when I buy the new (RU11) ballast resistor?

Click to expand...

Although there are variances and considerations in the running dynamics of the systems and with measurements, you likely currently have a 0.5 Ω (ohm) ballast resistor.

Without directly measuring the current resistor, the value can be estimated as follows, measuring at a temperature of 70-80 degrees Fahrenheit at the resistor and ignition coil:

1.Your measured voltage at the ignition coil positive (+) terminal is 9 volts DC.
2. Stated resistance of the coil primary winding is 1.5 Ω.
3. Current flow through the primary winding is 9/1.5 = 6 amps.
4. Assuming a nominal 13 volts, for sake of the calculation, delivered at the ballast resistor, which will vary depending on the state of battery charge plus alternator output, and connection/wiring voltage drops. Measuring the voltage at this point would yield more accuracy.
5. Voltage drop across the ballast resistor using 13 volts delivered is 13-9 = 4 volts.
6. Resistance of the ballast resistor based on available voltage and current flowing in the primary circuit is 4/6= 0.67 Ω

The calculated resistance is not exact due to the variables and conditions involved and temperature is somewhat discounted, but with that and considering manufacturing and measuring tolerances, 0.67 Ω is close enough to 0.5-0.6 Ω.

Or, the resistor can be measured directly.

Additionally, nine volts at the coil with engine running is not something to be concerned about.

RR Fan Dan said:

You ought not have said that. 3, 2, 1,……..

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