Hi Puffitu,
The information below was given to me, maybe it is of any help to you;
There were a couple dozen different carbs used on those motor.
Find carb part number, like
tc119a
tc107a
tc138a
Jet sizes for a 3 cylinder motor with 3 carbs are .070, .074, etc.
Jets for a 4 cylinder with two carbs are larger, .092, .094, etc.
Id the carb, then verify the correct jet installed for your altitude.
you can sort through all the carbs, and the corresponding jets per altitude, on
the mercruiser parts dot com web site.
Note, the top/middle/bottom carbs are not necessarily the same, and the jets aren't either.
Last edited by
roscoe; June 26th, 2019, 09:30 PM.