1946 Roadmaster carburetor problems

[Jon Mattey]

My 46 roadmaster was difficult to start when cold ,rebuilt the carb as the accelorator pump had rotted , the rebuilt carb made the car start easily but when it got hot itran fine at speed but neutral throttle or tickover it would miss fire as if "over fuelling" then backfire when throttle opened up. I fitted a brand new carb which ran fine but then started to flood, might the fuel pump pressure need reducing or ???

    Thanks Jon

[joelj]

Its possible that vacuum leak around the intake manifold can cause some of the symptoms that you described. 

[NailheadBob]

If @drhach views this post he might be able to shed some light as he has been working on his 1942 Special carburetor and fuel pressure issue.

 

 

Bob

[drhach]

Not sure I can add much, other than to suggest starting with the basics, like timing and ignition health. I know that doesn't point to the carburetor but I've found it's important to have those parts in working order so you can at least rule them out. It's hard when you change parts without really knowing the source of the problem. Sometimes that can introduce a new issue without solving the original one. 

 

If you have a question about fuel pressure, maybe hook up a gauge and measure it? I wouldn't think that these pump could really overpressure the system, but I suppose it's possible. 

[carbking]

Fuel pressure is stated as 3 1/2 psi, with an absolute maximum of 4 3/4 psi (original fuels).

 

With the volatility of modern fuels, I would think that maximum would be now be 4 psi (or less).

 

As mentioned above, a fuel pressure gauge would confirm/deny a pressure issue.

 

Jon