My 1914 touring currently has a later starter engine and is equipped with a Holley NH. It has always performed great, just like the one on the Coupe. Recently the touring has been playing up and on Friday it would not run worth a damn. So on Monday I pulled the NH off and gave it a through inspection. I found there was no nameplate on the device and the passage below the nameplate was completely blocked. Normally this hole allows air into the mixing area, I think for the idle. Well the hole was completely blocked, even air pressure would not clear the passage.
So I removed the spray nozzle, I had to drill it out, very carefully, and sure enough stuff had fallen down the hole and blocked the area at the bottom of the spray nozzle. I bought a new spray nozzle, cleaned out all the passages, stuck it back in and all is well.
The nameplate is essential to the correct operation of the Holley NH, who knew?