Please present your data, or at least direct people to where they can find it for themselves.
From the information you have presented, my initial idea is ... “you miscounted”.
More specific answers require more specific questions.
Exodus 12:40 says 430 years.
Genesis 46:11&46 says that Kohath was among the group of people who went down to Egypt with Jacob. He was a part of the 66 who went down. So Kohath had to at least be alive at the time of going down to Egypt.
Kohath died at 133, (Exodus 6:18)
His son Amram died at 137, (Exodus 6:20)
And his son Moses was 80 at the time of the Exodus (Acts 7 & Exodus 7:7)
Well, 133 + 137 + 80 = 350.
So, I can only get 350 years maximum.
How do I get it to add up to 430?