Just seemed like neither size wanted to go on. I got about a third of the nut on and it just stopped like it was trying to cross thread. I'll try cleaning them up tonight and trying again.

Seems as though neither 16 or 24 fits the studs. Could it be metric?

Awesome, thanks.

Does anyone know the size of nut used to hold the carb on the intake manifold of a 49 288?

Thanks for the welcome humanpotatohybrid!

Ive been through a carb or two in my time. I have seen other WDO carbs online it just seems like the 644s is a harder unit to find secondhand without it being rebuilt by a company. And if the numbers were something like CFM or an identifiable parameter for performance then I could say ok for sure a 650s would work but not really smaller than that. Dont want to find a smoking deal on a hypothetical 250s just to find out it doesnt have enough cowbell to idle the motor. Also the accelerator switch is gone as well so have to either source one or do a button in the cab.

Its mainly the numbers that are throwing me for the loop. I know if we were talking Holley 650 or 750 we are talking about CFM and I can kinda judge on what is needed but I have never seen number sets like these.

Hey all Im new to the forum, just bought a 49 Standard 8 thats been sitting since 1984. Pretty much as barn find as you can get on the outside but the interior is still in one piece. On to the issue I have at the moment, the carb. So when I bought the car the carb had disappeared at some point over the past 4 decades and was no where to be found by the owner. According to what I have found the car is suppose to have a Carter WDO 644s carb, cool. As I am not really willing to pay out hundreds of dollars for a rebuilt one my question is what models of Carter carb will work on this 288? I see different WDO carbs but have no idea what the number means on these. I know the WDO has the fuel connection I need but whats the difference between a 644s and say a 502s? Are there any other models than WDO that work on these?