74 Mark Charging Issues

Good morning i have a 74 Lincoln Mark that won’t keep a charge on the battery. I have replaced the battery, the alternator and temporarily bypassed the voltage regulator. At the battery while the car is running, I get about 13 volts unstable. With the replacement of the regulator cause me to get a good full and reliable charge?
Sincerely,
A.J.
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A.J. –
To answer your question simply, replacing the voltage regulator will solve a charging problem ONLY if it is faulty. The alternator, regulator, battery and their related wiring work together to keep the battery in a charged condition. Even though you have installed another battery and alternator the possibility exists that one of them could still be the problem. New parts can be bad. Because of this your charging system along with the battery should be tested using the correct equipment in order to pinpoint the failed part. Many local automobile parts stores offer this service at no charge. They will do these tests on the car or if you remove and bring the parts to them. At the same time I recommend that the battery be tested in order to verify that it can actually receive, hold a charge and be able to withstand a load test. If you are confident that the alternator, battery and the wiring is ok you may opt to install a new regulator as a test.
You don’t indicate in your information if your battery is always undercharged, dead overnight or weak after several days etc. so another point to consider is the possibility of a power draw from another area in the vehicle. Many times in the past we have found that items such as courtesy lights, glove box lights, clocks etc. can discharge a battery after a period of time if they are faulty or remain on. We have also found that alternators that perform well with the engine running will draw power after the engine is shut down. I hope that the above helps to resolve your problem. If you need any further advice feel free to contact us at any time.
Sincerely,
Bill