The Stovebolt Site Forums The Shop Area Engine Shop High Fuel pressure??

'59- '62 235
So I have been having some carb issues. It all started with me noticing that my Rochester 1bbl was weeping fuel out of the gasket between the bowel and top portions of the carb. First thing I did was disassemble the carb and check the Float level and drop. They were both off, so I adjusted them to spec, put it back together and re-install. Fired her up and it started to weep even more. I got frustrated and decided to install a Rebuilt Carter YF that I had lying around. Installed that, fired her up, runs good, but I'm getting weeping out of that carb as well. What's weird is, both times I removed a carb ( with engine off of course ), I was getting a very high pressured spray from the fitting at the carb inlet. Is this normal? Is it common to install a fuel pressure regulator on a stock application such as a 235 with a 1bbl Rochester or Carter YF?

what was the pressure? we need an actual number, and no it isn't common to install a pressure regulator, the pump will only put out so much pressure. it is only a spring that pushes the diaphragm. So when the needle valve is closed the spring just compresses until you need fuel. As far as I know the rochesters leaked coming down assembly line. I'm not certain what the pressure should be, but mine runs around 3 or 4 psi. and yes you would get some spray until the spring relaxes. But here again, I didn't see it so I couldn't say for sure if it was abnormal or not. I am pretty sure you don't excessive pressure, but I have seen some weird things in my life, so until you can get a quantitive reading, it will be hard to tell

Thanks for the reply. I do not know what the pressure is, it just seems odd that I have two carbs that are weeping fuel. My thought was that I have too much pressure and it is blowing past the needle valve. Can I just attach a pressure gauge to the end of the fuel line, or does it have to be plumed inline with the carb?

if you had enough pressure in the line to spray some fuel out when you disconnected the line, the carb needle must be working fine - it's a surprise when these old carbs don't leak some where, and if you need a regulator the pump is the problem .... use a good straight edge and check the mating surfaces between the horn and bowl body, it's common the screws have been over-torqued in the last 50 years and things are warped, you might need a better gasket there

Bill

Thanks red58, sounds like a logical explanation. I'll do that tomorrow, let ya know what I find.

Oh, if you were thinking it was getting past the needle valve you would have gas pouring out of the carburetor where the accelerator pump linkage goes in, all over the exhaust, it MAY run, but very, very poorly. And I haven't seen one that doesn't leak a little bit, did you use new gaskets? I had one with the float DROP set to low, and when the fuel would evaporate it would stick to the bottom of the bowl and just pour gas out in streams. As someone here told me, the current fuel formulations tends to be rather sticky when it dries out. I suppose if the fuel bowl is full you could just attach the pressure gauge to the end of the line, it wouldn't run very long, but long enough for your purposes. It probably doesn't matter, if you know the pressure or not, but when I was having my trouble with gas pouring out, I was thinking I might also be getting high pressure, as it turned out I had a little tiny speck of rust in the pump, and I was just barely moving enough fuel up to get it to run and pour out all over the exhaust. It didn't put out enough pressure to make the gauge barely flutter. That may have had to do with there being virtually no resistance to flow as well, I'm not sure. Any way the rochesters are notorious for leaking. A little weeping is probably OK, but if you are leaking enough to actually get drips, I wouldn't consider that OK. But there is certainly no harm in trying to make it better.

Thanks for the reply. Another thing I wanted to ask is, how full should my fuel filter housing be? Mines full to the brim, is that ok, or should it be lower? Is the level of the fuel filter housing a good indication of your " Float Level and Drop " calibration?

What type of filter are you using? mine only fills about half way, but I have one of the fram G1 inline filters, I have a nice glass bowl unit with the ceramic element that I can install right on the carb which may fill up to the top, I don't know since it is sitting NEXT to the truck right now. Hoping to install this weekend.

It's the kind with a paper filter inside. Here is a pic ( before I installed the engine )
http://i1236.photobucket.com/albums/ff441/AZ59apacheguy/IMG_1037.jpg

I can't say for certain, but I would think full would be normal for that set up, which is similar to what I am putting in only with the ceramic filter.