Syncellus has 1685 BC. The St Jerome Chronology, which seems to be part of Roman liturgy / Latin rite liturgy since late XVth C. has 1510 BC.

Now here is an interesting reading:

The standard dates for the Middle Kingdom are from about 2030 – 1650 BC, which includes the second half of the 11th Dynasty, along with dynasties 12 and 13.

From : 800 EGYPTIAN TOMBS DISCOVERED FROM EXODUS PERIOD
by Steve Law | Sep 21, 2018 | Evidence |
http://patternsofevidence.com/blog/2018/09/21/800-egyptian-tombs-discovered-from-exodus-period/

And a bit lower:

One clue from the 12th and 13th dynasties that fits the Bible’s Exodus account is the fact that pyramids during this time were made with mud bricks. The Bible does not say anything about the Israelites building pyramids, but it does emphasize the making of mud bricks during their time of enslavement. In the Old Kingdom, pyramids such as the Great Pyramid at Giza were built with stone blocks, not mud bricks. During the Middle Kingdom, pyramids were made with millions of mud bricks and then cased with stone on the outer faces.

Pyramid building ended at the close of the 13th Dynasty when Egypt fell into a dark period. Even after it recovered its power more than a century later, large pyramids were not built during the New Kingdom. The ongoing demand for bricks used in pyramid-construction during the Middle Kingdom matches the Bible’s account best.

Now, Exodus beginning Second Intermediate Period makes sense.

With Ussher, St Jerome, based respectively on Masoretic and not Vulgate but LXX, Exodus is more recent than 1650 BC.

In Syncellus - also based on LXX - Exodux is 1685 BC. Older than 1650.

I got 1602 BC by counting back from Syncellus date for King Solomon's unction after counting forward four years from that, by the 574 years I counted in Acts 13.

However, I counted 450 years of Judges (as given in Acts 13) as including both Joshua and Samuel, but if they are just the time between death of Joshua and beginning of Samuel's judging, you need to add 40 years on either end. 1682 BC.

Well, if so, the carbon date of 1650 BC can be matching a real date of 1685 BC. Dated 35 years too young would imply carbon level was at 100.424 pmC.

If then the taking of Jericho was in 1645 BC, dated as 1573 BC, carbon level was still rising, 72 years too young = 100.875 pmC.

This would mean that carbon levels have gone somewhat down since then, not sure how long they continued to go up ... I tried to see if carbon dates keep going too young to the Temple of Solomon, but found no carbon date for Temple of Solomon (not meaning there isn't one).

Now, other bit involved.

Syncellus gives no date for Joseph in Egypt.

I'll go to Birth of Isaac and Joseph in Egypt, receiving death of Joseph in Genesis 50 as probable real date for Djoser's coffin, supposing that Djoser was Joseph's Pharao and Joseph was Imhotep. I'll get Ussher Dates, take distance, and then apply that distance to Syncellus' date for birth of Isaac. Which is 2089 BC.

About 5300 Years Ago There was a World Wide Flood? Iffy ...
http://creavsevolu.blogspot.com/2017/03/about-5300-years-ago-there-was-world.html

Actually, as the site where I can still access Haydock, unlike the previous Haydock site, leaves out the Ussher chronology (which is consistent with the Vulgate and therefore not automatically banned by Catholics), I go to AiG's and CMI's chart for Ussher.

Abraham born 1996 BC, Family enters Egypt in 1706 BC.

1996 BC
1706 BC
0290 years

2189 BC
0290
1899 BC

In Syncellus, Jacob's family would enter Egypt in 1899 BC. How long after that is last verse of Genesis 50?

Jacob died after 17 years in Egypt (Genesis 47:27), which would have been

1899
0017
1882

in 1882. But how long after that did Joseph die?

Well, let's take 1882 BC as a standin for Joseph's death, so much more as Djoser can have died before Joseph. Djoser's coffin has carbon date 2600 BC.

2600 BC carbon "date"
1882 BC real date
0728 extra years

This means, in Syncellus' chronology, there was a level of 91.57 pmC at death of Djoser, which would have risen to 100.424 pmC at Exodus.

1882
1685
0197

In 197 years, the normal decay is to 97.645 % of previous level (97.645 pmC if previous level is 100 pmC), and so the replacement is a production of 2.355 pmC points.

91.57 pmC * 97.645 % = 89.414 pmC (*)
100.424 pmC - 89.414 pmC = 11.01 pmC
11.01 pmC / 2.355 pmC = 4.675 times faster

So, from Djoser, if Joseph's Pharao, to Exodus, the Syncellus chronology implies a factor of carbon production of 4.675 times as fast.

From Exodus to Jericho?

1685 BC

100.424 pmC, 35 years off, "1650 BC"

1645 BC

100.875 pmC, 72 years off, "1573 BC"

100.424 pmC * 99.517 % = 99.939 pmC
100.875 pmC - 99.939 pmC = 0.936 pmC
100 pmC - 99.517 pmC = 0.483 pmC
0.936 pmC / 0.483 pmC = 1.938 times faster

So, from a carbon production 4.7 times as fast over 197 years, it slows down to 1.9 times as fast over next 40 years. Feasible, provided the 4.7 times as fast was not the changeless speed over all the time, but that in fact it was so around midway, and ended near 1.9 times as fast.

(1.938 + x)/2 = 4.675
1.938 + x = 2*4.675
x = 2*4.675 - 1.938 = 7.413

Meaning, in 1882 BC, the carbon 14 production would have been 7.413 times as fast. This is a theoretical value, since the distribution of speeds could have been uneven. What was the Syncellus factor between Genesis 14 and Djoser's coffin?

2109 BC

87.636 pmC, 1091 extra years, "3200 BC"

1882 BC

91.57 pmC, 730 extra years, "2612 BC"

227 years, normal decay 97.291 %, normal replacement 2.709 pmC points

87.636 pmC * 97.291 % = 85.262 pmC
91.57 pmC - 85.262 pmC = 6.308 pmC
6.308 pmC / 2.709 pmC = 2.329 times faster

Now, the worst quibble against Syncellus chronology, from carbon p o v, would be the speeding up between a) 2.329 times faster between Genesis 14 and Djoser and b) 4.675 times faster between Djoser and Exodus and starting at 7.413 times faster.

I think, Syncellus chronology is still feasible, as well as St Jerome chronology being so, in a way which Masoretic chronology is not.

Hans Georg Lundahl
Nanterre UL
St Cleophas at Emmaus (**)
25.IX.2018

(*) Results and terms have been reduced to 3 decimals by rounding after the calculations from here on. (**) Apud castellum Emmaus natalis beati Cleophae, qui fuit Christi discipulus, quem et in eadem domo in qua mensam Domino paraverat, pro confessione illius a Judaeis occisum tradunt, et gloriosa memoria sepultum.