I'm having a hard time identifing my carb. Does anybody know what carb came one th 420 hp from Mercruiser. I know its a holly 4 barrel with no choke?

800cfm Holley with mech secondaries. I'm about 90% sure on this.

This carb has no choke bowl so I cant find the serial numbers. The only number i found was 8543 with a 4 under it on the top right hand side of the float housing?? Mercruiser said it should be a 4781 but when I go to holly the 4781 looks different. ??

My 420's had 800's with electric chokes. Maybe your carbs aren't stock.

hollley 9022, electronic choke.
contact chief engines. ft laud, fl.

800 cfm Holley/ mechanical secondaries & electric choke.

9022 is correct.

Here is the basics on the set-up from Holley. I don't know
if Mercury rejeted these or not:

800 CFM 4150 Marine
Front jets: 72
Rear Jets: 87
6.5 powervalve in primary

Compare to what you have now in the carb. The guys are
right, you may not have the factory carb.

OR