The 1910's were pretty rich everyplace right out of the box. Most will have a very "fat" idle circuit, so not sure why you would need even more idle fuel from one unless it has a HUGE camshaft in the big 455 and low compression.
A stock 1910 more times than not needs leaned up a idle, not fattened up.
Edelbrock did use at least 4 different calibrations in those carbs from what I've seen. They also had fundamental issues with them and machining errors, so difficult to say exactly what's going on without seeing it......Cliff