Gyro-Flow IR GRB-125 Running questions

[hamel01]

Hi All, So I bought a new to me 1960's IR GRB-125 Rotatory Screw Compressor. It was is pretty rough shape cosmetically so I have since tore it down and repainted/repaired the unit. I have put new gaskets in the air sep flushed the compressor oil, rebuilt the carb.... Before i tore it down the regulator was not working to slow the engine down and unload the compressor. In the tear down i found that one of the copper lines going from the regulator to the air control valve was broke. I have since fixed that but now i can not get the unit to run right. With all the carburetor linkage hooked back up the unit will start and run at what i would call a fast idle. As soon as the internal air pressure reaches around 45-50 psi the unit stalls out. I am unable to pull the throttle out to speed it up as the air regulator will not let it move. If I disconnect the air regulator from the governor linkage I am able to control the engine speed and can keep it running while it builds air but I have to constantly control it manually. According to my manual i should be able to pull the throttle out to the warm up speed when first starting it so the engine has enough power to over come the air pressure build up. I am not able to do this as long as the air regulator it connected.Before tear down it had a broken throttle cable put you where able to pull it to speed the unit up and it would sit there and run at a high speed... I am assuming i am missing something very simple but i can not find it. Is any one familiar with this units and would not mind spending a few minutes on the phone? Or maybe you know of a shop that still deals with these??

 

[NDT]

I'll tell you how my gas Sullair 125 works. When you start the engine, the throttle is wide open and the unloader valve is wide open. It runs like this until it reaches 125 PSI or so, at which time the pressure control gradually simultaneously closes the unloader and moves the throttle to idle. As air is drawn, the engine will speed up and the unloader opens. Every compressor, gas or diesel that I have used, operates like this. Sounds like on yours, since you are not at full throttle, the unmodulated air end is overloading the little engine.

 

[hamel01]

OK here is an update.
I disconnected the governor and the linkage from the UL88 (Air Regulator) and ran it by hand. I am able to control everything just fine and the compressor runs perfect. What i did notice though is that when I open one of the air valves to bleed off some air I see the UL88 arm move as if it is calling for more engine speed. The interesting part is if you follow the linkage that movement (if connected) would slow the engine down by closing the carb. So to me someone has something backwards. I think... Here is a pic of the linkage and the back of the carb. Does it look like yours?

 

[NDT]

Mine is a Sullair so it is similar but not the same. I suspect someone who did not know what they were doing tried to fix your compressor and changed some linkages around because they missed the leaking copper pipe.

 

[Ray70]

Is it possible that someone, at some point installed the arm on the carb upside down? causing the throttle to move backwards when calling for more throttle?
I'm not familiar with the unit so I have no idea if the arm will physically even go upside down, but I have seen people do silly things like that before.