Originally posted by 79C10
It only seems to do this when im around 65-70MPH. On the other hand I can be cruising around 45MPH with it whining at 5000 RPM with the secondaries open and it performs top notch. So I don't think its related to engine speed.
It won't shutter/pop at anything slower than 60MPH
i have no real chevy-specific experience yet (just european engines), but ill put my 10 cents worth in as ive been taking advice with out giving any...

it seems very strange that it never happens below 60mph. as you say, it looks like its not related to engine speed. could there be something that happens to your ride only over 60mph? by this i mean some kind of wheel speed related vibration which then causes some other prob with the carb? prehaps wheel bearing or something? i know most fuel bowls really dont like been shaken around too much (even if its only a small high frequency vibration that aint that noticeable)

prehaps the increased air pressure/ram effect through the grill at speeds over 60mph (and prehaps therefore the airpressure into the airfilter/carb) can cause probs with the carb operation when the secondaries are opened?

i'll be quiet now and crawl back into my beginners box

lobster