An internal-combustion engine needs four things to run. They need fuel, mixed with air, in a ratio of 14.7 to one. An ignition-spark lights the fuel and air mixture, creating combustion. Compression of the fuel and air mixture makes it explosive. The final necessity is proper timing, of the components.
1 The length of time it takes for eggs to hatch after incubation begins depends on the species and temperatures. 2  For bluebirds, it USUALLY takes about 12-14 days from the date the last egg was laid.3  Different species have different incubation periods, which can vary within a species due to temperature inside the nestbox. Depending on when incubation begins (on the last, or next to last egg), eggs in the same nest can hatch a day or several days apart. 2  It also takes a while for the bird to break through the shell. 3  It could be a new egg from a subsequent nesting if you didn't clean the box out immediately after the last fledging.
Eggs should not be keep more than 10 days to 2 weeks after they have been set. Eggs that are to held several days before incubation should be held at a slanted position (35 degrees) You can do this by using a egg carton and proping it up with an object at 35 degrees.nce the light shines through you will be able to tell if your egg is fertile. After 72 hours in the incubator you can take the egg out and check. If the egg has a dark spot in it it is fertile. The dark spot is a typical blood vessel formation that looks like a spider.