[GDB]

Is it necessary to have a pcv into the carb or can I plug it off.I have a Holley 750 carb. On my old valve covers I had a pcv and a breather but on my new valve covers I really only have one opening that I guess I should use for the breather.

[dave-r]

You can use a breather on each valve cover. I wouldn't like to use just one breather on one cover myself.

What will happen is that pressurised crankcase fumes will exit the engine via the breather(s). OK on a race car but not ideal on a street car.

Why? Because 1 the fumes are going directly into the engine bay and into your interior. 2 because the breathers will clog up with oil and need cleaning frequently. In particular one placed on the passenger side of the engine.

On a PCV system the breather is there to allow air INTO the engine. The valve takes the fumes out and they are burnt in the engine. It is a much cleaner and neater system.

What brand of valve covers are these? Is there no provision for a PCV system at all?

I know the MP cast covers need the holes drilled.

[dave-r]

Two more points. If you remove the PCV valve and block off the fitting for it on the carb then you will need to re-tune the carb.

If you do fit a PCV valve make sure it is on the drivers side valve cover with the breather on the passener side.

[GDB]

They are MP and I can punch the hole out on the other cover now that I know what I need to do. Thanks for the advice.

[Jon]

Since we are on the subject of PCV. What would prevent a backfire through the carb from traveling down the breather tube and igniting the fuel tank breather?

The car was built in the LA plant and has this feature. The fuel tank breather is the silver 5/16" tube on the left side of the picture. I know it can simply be diconnected but we are environmentally concious here in California.

[dave-r]

I am not sure you could sustain a flame front right through that lot. The fumes in the pipe would probably be too lean to ignite anyway.