I just finished installing a new Brassworks radiator in my 26 speedster. I had a couple of overflow tube gushers but they seemed to stop. I'm wondering if I may be overheating though. The head seems to be really hot also the tank too. However I could hold my hand on the outlet pipe. I'm not seeing any murcury in the radiator cap. Do those go bad? Could I have air trapped in the jackets??
Will -- The gushing probably was the release of excess coolant. Don't fill the radiator completely; just cover the top of the core and it will be happy. No hot indication in the motometer is a good sign.
Moto meters can fail and not read. Most likely the radiator was just over filled. She will push out the overflow in that case. The head and upper part of the radiator are supposed to get hot, but not too hot. Do you have a IR temp reader to check head temperature?
Have you checked to see if you have any restrictions in the water jackets? Any restriction or sludge build up can be an overheating problem. If the timing and carburetor adjustment is OK you could have some blockage somewhere.
You didn't mentioned if your engine is a new rebuild.
If it isn't remove the head and make sure all of the water passageways are open in the head and block.
Even a new radiator wont improve an overheating problem if the head or block has restricted cooling passageways.