Is a rpm drop normal when the gridheaters cycle on cold mornings or should the engine just change load without a rpm drop?

 

How much is it dropping? What rpm is it idling at? Grids pull quite a bit of current so they are making your alternator earn its keep. Thus putting more load on the engine, with that a little drop in rpm at idle.

 

it idles at 875 and will only drop alittle on and off until engine warms up good. the only reason I ask is because Ive been reading some posts that links bad pumps with a rpm drop, but they probably mean when the engine is completly warmed up.

 

Totally normal. That is the alternator pulling a big load.

 

bad pumps usually are more noticable when driving... slight hesitation lack of power in take off etc...
your small rpm drop is normal