Because if there’s only 6-7 volts at the red wire with a Ready to Run system there is weak or no spark. I guarantee it. This is an electrical installation/wiring issue. I have seen this complaint several times before.
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Maybe the OP’s battery is good & just needs to be recharged overnight w/a shop battery charger. I’m getting the impression the OP’s MSD ignition module may be powered via the ballast resistor wire. Suggest OP double check, as it probably should be powered full-time (running, starting) from a battery positive source.
fyi, a “resistor wire” (aka “ballast resistor” ) looks more or less like a normal wire, but the conductor is made using a higher resistance metal alloy than copper. Similar to ni-chrome wires used in toasters. Using an actual discrete resistor is possible too, but the discrete resistor would have to have quite large dimensions to handle the electrical power rating needed. Using a resistor wire saves engine compartment space.
Ah the good old days. 
You don’t know that if it hasn’t been tested. You are making an assumption. You don’t know what kind of meter he is using (digital, analog, ohms/volt). That can change the results.
Could always hotwire it to test coil wiring
Run a wire from the positive post of the battery to the + side of the coil and try to start it.
If it starts will have to disconnect that wire to shut engine off
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True, I’m relying on the fact that he is using a meter that reads voltage properly. Whether it’s digital or analog shouldn’t matter. But the fact remains that with 6-7 volts, there is no spark.
I have said that multiple times…
I must have skipped over those posts
BUT I may have solved the problem
What’s missing in this picture
The wire that sends 12 volts to the coil during cranking
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Well it does. A digital voltmeter does not load down a circuit so it will read the highest possible voltage. An Analog meter is rated at ohms/volt. That determines how much it loads down a circuit. A good analog meter will have at least a 20kohm/V rating and will give a pretty accurate reading where a $3 Harbor Freight special at 1kohm/V or less can reduce the reading by a significant amount.
I can give you an extreme example from my days running the Three Phase QA/testing department of a major distribution transformer manufacturer. We had a large three phase 36kV transformer come back because the customer was detecting voltage on the HV bushings that were in the off position.
This model had a switch which could select the A bank bushings, B bank bushings, A & B bank bushings or none. It was in the A bank position so B bank should have had nothing on them. They were reading about 450VAC with 36kVAC on the A bank.
We read the same thing with our digital voltmeters, but 0 V with our analog meters, even with a VTVM which has about 100kohms/V. It was simply the wires from the B bushings to the switch were being induced with voltage from the primary coils when A side was energized. The current was so miniscule that the slightest load would bleed it to zero.
All transformers with this type of switch do this, but is was hard to convince the customer. IIRC they eventually accepted it.
BTW, I’m not saying that you are wrong about the voltage on the red wire being the issue, but I am saying that it should have been tested to see if it has spark before starting down this troubleshooting path.
May be bypassed…
Don’t have to run a relay as long as you have a good B+ (12V) source…
Does it ever start while cranking or when it does start, is it as soon as you release the key from the crank position?
In the Holley pdf file that Davesmopar linked to above (frm33565_ready_to_run_add.pdf), it states:
Many vehicles, primarily those that were originally equipped with breaker
points, have resistance wiring or a ballast resistor in the coil positive (+) wiring.
This reduces the voltage at the coil positive terminal. An MSD Ready-to-Run
Distributor requires a solid 12 volts to perform at its full potential. By adding a Relay,
PN 8961, you can ensure that the distributor receives a full 12 volts during
cranking and while running.
That verifies that the MSD distributor needs full available battery voltage during cranking. But from Quig’s readings, we know the voltage at the MSD distributor is between “2.5 to 3.5v” lower than the available voltage at the battery.
The fact that available battery voltage is only 9.5v during cranking doesn’t bother me as much as the voltage at the distributor during cranking is down to 6-7v.
If it was bypassed properly, that wire would still be there.
The distributor he has, has an electronic switch instead of points. The switch is basically a magamp (magnetic amplifier). It does not need a current limiting wire (resistor wire) so it seems the simple solution is to replace the resistor wire with a stranded 12 or 14 ga copper wire.
Bypassing the ignition resistor has been discussed for 3 days.
Also:
The battery needs to be recharged, the state of charge is definitely low.
I concur. However the biggest problem I experience using a DVM for car-diagnosis is when the voltage is changing at the same time I’m trying to measure it. The DVM’s circuitry assumes the voltage is holding steady, and gets confused if it is changing. The analog (moving coil) method is better for that situation. Possessing both types of multi-meters makes a lot of sense for diy’er car repairers.
My DVM is pretty old and suffers from that condition, however, I have been told that new higher end (basically NOT the $3 special at Harbor Freight) have improved a lot since then. I just haven’t needed to upgrade my DVM yet.
Here is what i did.
But the wire that goes to the Coil + is heavily corroded.
It is difficult for me to tell where this wire goes but now it actually fires but immediately turns off when i let the key go to ON from START.
