Soaked Briggs carb in cleaner overnight, used wire and air to blow out
Might need to boil the carb per Bertsmobile1's suggestion. Could take a few times to get it clean.
From Bertsmobile1 below. Great advice.
"Before I got the ultrasonic cleaner we used to boil carbs using a big pot & a dishwasher tablet
The ones with the ball in the middle seem to work better
A nice rolling boil works best
Give it an hour or so then boil some more water and take it out of the boiling soapy water then strait into the boiling rinse water
Give it a 5 minute rinse hen take out & blow dry.
Do not allow the carb to sit in the wash water unless it is boiling or it will oxadise.
Some like to do a pre-rinse in boiling water with some vinegar in it to neutralise the alkaline soap first."