codes in service engine light

When i turn the key on in my 79 chev van with 350 cu in and I try and start it before the Service Engine lite blinks off briefly it will not start. if
i let the light blink before hitting the starter it will not start. Whats this all about. I've had ASC mechanics look at it and they are clueless. the computer and the electric part of the distributor check out ok.
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