Oh crap..... Internally balanced engine with an external balance flex plate?!

My 610 horse 408, that runs 10.60's. With a solid roller 760 lift cam, idles at 950 rpm, and purrs like a kitten without rattling the car apart....just because its not an efi engine doesnt mean it rattles the car apart. I also have poly spool mounts.

For comparison sake, I had a less than optimally built 323 that idled high, and shook more than the 408.

The "big engine" shakes analogy is a mask for other factors. Just like "big cams have to idle at 1400"...