Edelbrock Rich At Idle

[bobscuda67]

I am having a problem with my car at idle. It's a 340 with a 650 Edelbrock. It idle's really rich and the plugs are black and sooty, and the idle mixture screws have no effect on the idle. It's seems to be pulling fuel through the transfer slots. Is there another way to get more air into it other than drilling the primary throttle blades.

 

[C130 Chief]

How much vacuum do you have at idle? Your metering rods may not be down which will cause a seriously rich idle/cruise. With the engine idling, loosen the screws that hold the metering rod covers on, and rotate the covers out of the way (no need to totally remove the screws) the rods/pistons should be down all the way. If not, you need lighter springs. If you cam has more than 230 degrees at .050, I'd suspect this. You may also want to experiment with more timing advance at idle.

 

[bobscuda67]

Thanks for the advice.
I have 15 inches of vacuum at idle. I did rotate the covers and the rods and piston were down all the way.
I have the timing set at 16 degrees, which is where Don at FBO setup my distributer.

I took of the carb and measured the exposed slot. It was .068 which seams like a lot. And I still don't have any control with the idle screws.
I did buy some NGK plugs one heat range hotter than the Champions I replaced, it didn't help much.

I know that drilling the primary blades is the old school way of fixing this, but everyone I talk to says don't do it. But they don't know how to fix it either.
When I called the Edelbrock tech line, the tech said to hook up the vacuum advance to the manifold port on the carb, which doesn't seam right to me.

The secondarys don't have the stop screw, like the Holley's, so I can't open them up a little either.
Someone out there surely must of run into this before.
I'm dead in the water untill I can get this fixed.

 

[70aarcuda]

change the metering rods?

 

[green1]

What is the timing? Start there.