I also sent mine out before I realized there was an excellent set of videos on rebuilding the 4000 by Mikes Carbs who also sells rebuilding kits.
Even after rebuilding, I still had a slight hesitation off of idle. Today, I decided to bite the bullet and start from scratch with all the carburetor adjustments (I did not try summer/winter hole positions on the shaft that activates the accelerator pump). Not sure, what eliminated the problem but the hesitation is gone and it idles nicely with no gas smell at the exhaust.
Larry
Larry Durocher
1956 Mark II C5601429
1962 RR Silver Cloud II drophead
2006 Ford F150
2010 RR Phantom drophead
2013 Bentley GTC
2015 Lincoln MKT