New Plugs - Harder Cold Start?

I have an older 914F engine,  black starter motor, old style ignition packs. Fresh fully charged battery.   During a repair last summer the plugs were changed out to new style 297-656-  three electrode fixed gap  (.031-.035) 

Seems like this winter i  am having more difficulty with cold starts compared to old style plugs   x27EPR-U9  set with MINIMUM gap .027  per LMM.

Is this my imagination or are other having cold start issues with new plugs?

Peter