All. I have reviewed a lot of great posts on the Holley NH carb. I trying to clean mine up and replace the gaskets. Two questions. 1) is there a diagram somewhere on where the gaskets go? I can figure out several of them but the small ones I do not know. 2) see the pic. Do I need to try and get this piece out? I think it is part #6214 - spray nozzle. Tried taking it out with a screw driver but it is so tight in there I am scared I will strip the slot out.
I have heated the area around the spray nozzle to a light red cast with a torch. Then let it cool and nozzle turns out very easy. Then replace with a new one. Has worked for me in several areas where brass/bronze to cast is involved.
Interestingly, sometimes the spray nozzle comes loose and blocks the passage of gasoline so that the car stalls. I would say blow it out with compresses air. If it works well, leave as is. No need to replace if its not broken.
I couldn't get mine out so I just cleaned everything, put it back together with new gaskets and have had no problems.
Heat from a propane torch works. Doesn't need much. Don't strip the slots. Use a properly big screw driver. The heat breaks it free and probably fries the small gasket under it which doesn't hurt loosening it either. Those are your 2 small gaskets. One under the nozzle & one under the needle seat.
Thanks guys. May leave it alone for now and see how it goes.
I have done the following on my carbs with good results. I had a NH that I rebuilt several times and it still was not right. I could blow carb cleaner thru all the passages, everything looked OK. Finally out of desperation and disgust I took the name plate off and removed the choke spring and then slowly heated the entire carb to a dull red color and threw it in a bucket of water. I said good riddance to it, as it sounded like it blew into a 1000 pieces. When I took it out of the water and blew threw the small drilled passages I saw one small "puff" of rust. At that time the light bulb went on in my old brain. The rust was restricting the flow thru the passages. Kind of like cholesterol in our passages. During the heating of the carb the lead plugs had melted out of the small passages. After a thorough cleaning of the passages, (be careful not to drill out the little ledge or stop for the lead plugs). I cut small pieces of 1/8 inch brass brazing rods and installed in the passages. They will hit the ledge inside the passage and then swell into the hole like a rivet when peening them down. Some carbs will already have brass plugs. You will have the cleanest carb you will ever have. I have done at least a dozen of them this way. All have worked better than before and I have not busted one yet. I may just be lucky, so I am saying proceed at your own risk, I believe (personal opinion) that the rusting of the passages walls restricts the flow. When you heat and remove the rust scale the passages may be ever so slightly larger, which may give a little more performance. ????
I recently had a new NH rebuild problem. The carb flooded over even with a new inlet valve and float installed. The old float had fluid in it and was too heavy, so it was replaced. When I put the carb on a flow test bench, it immediately filled and ran over up through the gas passage and out the rear air inlet, like the valve was defective. A closer examination revealed that although the carb frame had been sand blasted clean, the vent hole from the top of the carb fuel chamber to the outside world had been originally plugged solid with grease and mud. It was still there. Another interesting fact was that there was no dirt or mud on the carb and it appeared to have been in a fire that burned it all off. The resulting inside air bubble was strong enough to hold the fuel level low enough to not turn off the gas inlet valve.