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Old 07-16-2020, 08:13 AM   #10
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Join Date: Dec 2013
Location: Minnesota, Florida Keys
Posts: 6,676
Default Re: Someday this engine will run right.

A "Load-a-matic" uses a combination of venturi and ported vacuum to run the advance mechanism. They require a carburetor with a port about half way up the back side of the carburetor with a vacuum line going to the distributor. This system was only used on Ford products between 1949 an 1956 and while it works well when everything is in good shape on a stock engine, it operates differently from all other ignition advance systems. A "regular" distributor can have mechanical (centrifugal) advance only or a combination of mechanical and vacuum advance. A mechanical advance works by using weights inside the distributor; as engine speed increases, the weights move out by centrifugal force which moves the point plate inside the distributor, advancing the spark (making it occur earlier in the combustion process). It should be noted that the Ford "Load-a-matic" system does not use a mechanical advance mechanism and depends solely on it's special vacuum advance mechanism. A "regular" distributor can also have a vacuum advance mechanism that works in concert with the mechanical advance. Basically, under conditions of high engine load manifold vacuum drops, the lower vacuum is detected by a diaphragm in the distributor and causes the spark to advance even more.

Clear as mud? In summary, a Ford "Load-a-matic" system functions differently from all other systems and requires a special carburetor designed specifically for use with it. lt should be noted that since the Ford system does not have any mechanical advance, the vacuum system has to be functioning or there will be problems.

As I said in an earlier post, the stock generator produces "dirty" power with voltage spikes that can damage am electronic device such as a Pertronix. As mentioned above, solid core plug wires can also cause problems with a Pertronix. I believe they specify spiral wound wires for their installations. Generally Pertronix systems do not do well on 6 volt systems.

Since you said that the car ran well for an hour with the Pertronix, I believe that we can assume that the distributor is in decent shape and the vacuum advance system is functioning properly. I believe that the Pertronix unit is "fried", either because you left the key on or (more likely) because of the "dirty" power produced by these old cars. In my opinion, the proper route for you to take at this time would be to get the proper points and condenser from a reliable source (such as NAPA) and install them according to the factory specifications. If you have a multi-meter, it would also be a good idea to use it to do a preliminary check on your coil. Set the meter to the proper "Ohms" scale and check the resistance of the coil. The primary circuit should be relatively low (less than 10 ohms), while the secondary should be high (over 10,000). Make sure the timing is set to the dot on the crankshafy pulley (with the vacuum line disconnected) and you should be good to go.

I have a similar setup as you (a '51 Mercury" engine in a '51 Ford). I have had the car a long time, and for the first 35 years I owned it, I ran a stock engine with a "Load-a-matic" and the car performed flawlessly. A couple of years ago, the original engine was starting to get a little tired, so I installed the Mercury, along with some finned aluminum heads, updated carburetion, and a Mallory dual point mechanical only distributor. The car still runs well, starts at a touch of the key, and the increased power is very noticeable.

Good luck on your quest.
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