The sophistication of the Quadrajet is lost on most people.
-Al
Back when I built the first 454 for my Malibu, I had an early model Quadrajet on it. I learned quite a bit about tuning on it, especially the rear air valve.
The local pick apart was a treasure trove for the tuning rods, both primary and secondary, as well as rod hangers,vacuum springs, etc.
I will admit it's been 15 years since I have fooled with one, but when tuned right, it was a darned good carb.
That 454 had a set of 049 oval port heads that I had done some pocket porting on. This was back when Hyd Roller Cams first came on the scene. Comp Cams had their version, I bought a .282 magnum Hyd Roller kit, which was about 224 degrees at .050, and .572 lift. It ran pretty good.
When I had set the thrust on the Roller Cam, I just used a stock sheet metal timing cover. I knew the old trick of placind a bolt between the water pump housing and timing cover to keep it from beating out, but just didn't do it. Over a period of time, the Cam developed too much end play. This caused the rollers to eat into the side of the lifter, (amazingly, the first Comp Cams Hyd Roller Lifters were not hardened), and one finally broke, ruining the block.
I got another block, put that same Cam in it with Crane solid Roller Lifters, and set the lash at .005. The thing ran really good. I put a lot of miles on it.
Much later, I stuck a set of Edlebrock heads on it with a Performer RPM intake. The heads upped the compression to 10 to 1. In around 2010, I took it to a shop and put it on a chassis dyno, where it pulled 360 HP at the wheels. That equates to an honest 500 at the crank.
That's the engine I took out when I had the 540 built, which opened up a whole new world of insanity.