Cliff, how to tune the idle circuit on a Rochester Q-jet on a Buick 430 -68?

[olahak]

Hi Cliff!

I'm wondering how to open up my idle circuit and optimize the carburetor on my Buick Wildcat 1968. There is a 7028248 carburetor on it, the car and the engine set up is original.

Which secondary rods, primary rods/jets should I have? And how much and how can I open up my idle circuit?

I've been talking to a guy here in Sweden and he says I can keep the #70 jets but change the secondary rods to CK or maybe CE.  And on top of that open up my idle circuit to get a steady idle. In that case maybe change the primary jets a few sizes.

I have screwed it apart and sealed the bottom well plugs. They were a little leaky.

I've appreciated your help

Best regards, Ola

[Cliff Ruggles]

If the engine is "stock", then the carb stock settings should be close, and the best place to start.  Those carburetors used very small airbleeds, and generous for idle and main fuel delivery.

Keep in mind that any variation or modifications may require slight recalibration.  This includes cooler thermostat, free flowing exhaust, headers, etc.

Also keep in mind that the stock jets and rods can be heavily worn, from years of the metering rods sliding in them.

We also see a LOT of power pistons with bent hanger arms, so make sure they are level and exactly even.

The power piston spring can rust and loose tension as well.....Cliff