Holley 4150 Fuel Inlet Leakage
I'm hoping someone here may have experienced the same thing I've started seeing in the past couple of weeks with the rear fuel inlet fitting leaking on my 1970 Holley 4150 Dual Feed Carb.
This carb is the only thing non-original to my `68 L72 427 (M21), and I'm using all stock configuration and diameter fuel lines with the factory style brass Tee fitting that splits the fuel lines to each inlet from the fuel pump. I'm also using the ceramic Inlet Filters and springs.
My problem started with the rear inlet fitting leaking slightly between the gasket and the rear Fuel Bowl that it threads into. It's hard to tell, but I believe there is also some leakage at the Fuel Line fitting as well. I've since replaced the Inlet Fitting Gasket several times, and replaced the Inlet Fitting itself with a new Holley fitting with no change. The threads in the rear Fuel Bowl seem to be in good shape, as I can thread the new Inlet Fitting into the bowl finger tight up to the gasket. I have always been careful not to over tighten the fitting or the rear Fuel Line.
The front bowl fitting, Tee lines, and Fuel Pump line are completely dry, and don't leak a drop. I noticed after pulling the rear line off again (for about the forth time in as many days) just after running the engine for about 15 minutes, there was a considerable amount of back-pressure in the Rear Fuel Bowl as I loosened the Inlet Line. It's been a while since I've delt with Double Pumper problems like this, but if I remeber correctly, the fuel in the bowl will just leak out when the line is loosened, and not actually have a whole lot of pressure behind it.
My questions for the knowledgeable Holley guys out there would be:
> Is it possible there might be some kind of restriction in the rear Fuel Bowl circuit that's causing back-pressure and blowing this Inlet seal out? As I mentioned, I've replaced several gaskets and the Inlet Fitting now, and they all still seem to be in good shape when I pull them out.
> Could the threads in the rear Fuel Bowl be damaged enough to cause this kind of fuel leakage? They don't appear to be, and I would think the gasket itself would still do its job. (There don't appear to be any nicks or damage to the sealing surfaces either).
Sorry to ramble on, but this is becoming frustrating. Any input or advice would be greatly appreciated.