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I am in the process of buying a 1972 Atomic four. It cranks, but won't start. I did a compression test. Three cylendars were at 100, and one cylendar is a 35. It went to 55 when I did a wet test. I'm guessing the no starting is a bad fuel pump, but am I in need of a ring job and/or complete rebuild?
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Joe,
Here is a short checklist that may help you get your engine started. I wouldn't consider any heavy maintenance until you get the engine started and give the low cylinder a chance to respond to heavy treatments with Marvel Mystery Oil (MM)). Apply 4 or 5 squirts of MMO into the spark plug hole of the low cylinder, trying to get it away from the manifold side of the engine. Run the engine until the MMO burns off, and then apply more MMO, burn it off, etc., etc.
CHECK LIST FOR NON-STARTING ENGINES:
1) Close raw water through-hull as soon as it's determined that the engine is not starting within the normal time.
2) FUEL: Remove the flame arrestor and check for the presence of raw fuel. If the choke is closed completely, there should be raw fuel puddled in the bottom of the intake throat within 15 to 20 seconds of cranking (3 or 4 five-second attempts). If the carburetor intake throat is "bone dry" after this amount of cranking, the reason for the non-starting is either a problem in the fuel supply which prevents fuel from getting to the carburetor or some problem within the carburetor that prevents the fuel from getting through the carburetor (most likely a blocked main jet).
3) Ignition: Remove the secondary lead from the center of the distributor cap and hold it approximately 1/4" from the cylinder head while someone cranks the starter. You should see a good arc between the end of the coil lead and the head that can be stretched to 1/2" or even 3/4". If you see no spark, the reason for non-starting is clearly within the ignition system, most likely a break down within the primary ignition circuit.
This quick check of the ignition system does not rule out timing issues. While the Atomic 4 has virtually no history of slipping out of time once the timing has been properly set, if the non-starting follows work that was accomplished on the ignition system, the timing should be rechecked.
4) COMPRESSION: With all spark plugs removed, hold your thumb over each spark plug hole to check compression as someone cranks the engine for a second or two on each cylinder with the starter. An Atomic 4 will usually start if any two cylinders have normal compression as indicated below.
a. Compression sufficient to force past your thumb no matter how hard you press it against the plug hole would confirm normal compression of approximately 85 psi or above.
b. If you can hold your thumb against the compression, but not easily, a compression value of approximately 40 to 50 psi would be indicated, and starting could be problematic.
c. If you feel virtually no compression on any one of the cylinders, the problem is likely a stuck valve.
5) If all of the above checks prove to be satisfactory and the engine still won't start, the problem is probably somewhere within the secondary ignition system, down stream of the coil. The components within this part of the secondary ignition system are very difficult to inspect, but they are fortunately not very expensive so I recommend replacing them in the following sequence: plugs, distributor cap, plug wires, and rotor.
Regards,
Don Moyer
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