Fuel leak at inlet fitting - how to seal properly?

Can anyone share the usages for these two fuel inlets? The threaded length is very different.

 

Anyone?

 

Larry, The first link is for the newer 1" port not the older 7/8". The carb on the car is more matched to the short thread length. My parts carb is threaded longer and from a "70 as is the fitting.

 

What is superior about the later 1"-20 fittings is that the seal is on the end of the fitting and the threads are NOT in the fuel.

Over many years of service the fuel erodes/deteriorates the threads and they end up stripping. The ONLY way you are going to strip the newer 1"-20 variety is to inadvertently cross-thread it during installation.

To date I've installed several thousand heli-coil into Q-jet carburetors. In all the years I still haven't done 2 dozen 1"-20 carbs, almost all have been 1971 or earlier models (Marine to 1988).........Cliff

 

Thats how I got past the twisted filter and threads in the gas on my previous carb.

 

That copper crush washer worked no leak. But my filter was twisted. So the one that tbe hand pointer is pointing at solved both problems.