V8 Staff

We’ll get back to the audio install soon, but I wanted to take a minute to touch on a tip for those who experience hard starting when your classic carbureted car sits for a while between drives, and especially GM cars with Rochester Quadrajet carburetors like our ‘70 Riv. It is pretty widely known that the original lower fuel bowl plugs can leak over time, draining the fuel into the intake manifold and depleting the fuel supply for the next start. However, there is another situation that could also be at fault.

The fuel filter might also be leaking internally, draining fuel back down the line to the tank. For this reason, there is a Fram part #CG3389 for long Q-Jet applications that features a built-in check valve to prevent fuel from leaking.

The rubber plug on the inlet side is the valve.

Comparing the stock type filter without the check valve.

It’s also important to install the filter pointing the right direction – this is correct, as the we are looking at the outlet side of the filter housing. The fuel comes in the other side, and is supposed to flow through the filter media and into the carb. If you install it backward, like this (shown without check valve) –

.. the inlet side will have the closed-off side pushed up against the fuel inlet hole in the housing and will restrict flow. Remember, the closed off side of the filter goes INTO the carb, not towards the fuel line.

This is the correct orientation:

We’ll report if the check valve helps with starting.

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