I just installed an MSD 6AL controller with my MSD Billet HEI distrib. I also installed on the 670 Avenger carb, adjustable blocks that negate using the jets. I set everything to normal, timing is good, air/fuel mix is good, idle good. This is a 355, auto, mild cam, edelebrock RPM heads, headers, and about 800 miles on the motor.
The car idles great. If I slowly bring up the RPM, at about quarter way, or 1700 rpm, it starts sputtering and a mild whistle is notable. If I quickly bring up the RPM, the whistle is very noticeable, but I can't tell where it is coming from. I pulled all the vac hoses off and capped the carb inlets to see if it went away. No go. Could sucking air cause this type of condition? I thought a vac leak would cause rough idle as well. Any help is greatly appreciated.

Bring the speed up to 'whistle' / stumble point and using your other hand, slightly cover the primary throat. If the engine 'cleans' up and smooths out, you're WAY lean in your transition circuit and I'd look REAL close at the metering blocks you changed. Compare blocks and gaskets for difference.

Thanks Dave,
I'll give that a shot. I forgot to mention, while bending over adjusting carb, my eyes would sting from the fumes, but there was no smell as if running rich. Is that normal?
I will definately take the adjustable blocks off again and see if I have a gasket backwards or something askew. With this MSD, do you think 8mm plug wires are a little small?

Problem solved. I took the adjustable blocks off, then readjusted the secondary float. Installed the original jets, adjusted air/fuel mixture, and tested again. It flooded and secondary would not adjust. Opened it up, found some debris from gasket in float needle, that's why it would flood. Corrected that, all came up fine. Had a hesitation, so I adjusted the accelerator cam and all is great now. Thanks for the help. graemlins/hurray.gif