Hard Starting?

["Douglas B. Gaither" <dbgaither@worldnet.att.net>]

My dad has a '73B which he lets me drive, while I'm restoring mine, for the
sole purpose of me keeping it in running order.  Here's the problem.

It turns over just fine, but there are times that it sounds as though there
is no spark getting to the fuel... until I let off the starter and it will
fire right up.  Until then, it just turns over and over with no signs of
life.

What is the prob?

Doug