'72 Spider cold start stumble

["Karl Maxon" <KARLM@domain.elided>]

After a head re-do a week or so ago, the following is occuring:

The engine "seems" to run on three cylinders for approx. 5 seconds upon =
cold cold startup, never on warm or hot startup.  I performed the Fred =
DiMateo test whereby I started the car, and the instant the missing =
stopped I turned the car off and felt the exhaust manifolds. =20

#4 seemed to be slightly colder than the rest.  I've checked and rechecked =
innumerable times the #4 fuel line and connections for leaks.  There are =
no apparent leaks.  There is NO apparent fuel smell at all.  Changed =
plugs, appears to be getting same mixture as the rest of cylinders - no =
affect on start up.

A few times, the "missing" did not occur.  I also tried slightly different =
start-up procedures, thinking it's slightly rich (which it may be.  This =
Thurs. I'm gonna put the car on the gas analyzer to check mixture, then =
I'll check the CSS for proper cold start enrichment, don't want to adjust =
it before I check the mixture).

IT HAS BEEN SUGGESTED last night, that it may be due to a slight leaking =
of the brake booster check valve, so that after sitting all night, there =
is additional vacuum at the number 4 cylinder becuase of the brake booster =
check valve at that location.  I HAVE had check valve issues before, which =
neccessitated removal of the checkvalve for thorough cleaning (check valve =
not sealing, causing booster pressure to go bye bye).  Could it be the =
grommet at the booster too, not sealing totally?

Any thoughts or insight on this condition I'm experiencing?  I have a used =
set of fuel lines on the way, so I can substitute the #4 line if I need =
to, as well as a used manifold with injectors, check valve etc.  Thought =
I'd check the booster grommet at the booster and check valve at the =
manifold first, since there are no apparent leaks from the #4 line.  My =
brake booster air line is fairly new.

Any help/sharing of similar problem diagnosis/solutions on this issue =
would be appreciated!!!! =20

Regards, Karl Maxon

------------------------------