I agree 100%!!! I bought the car from my dad with the 670av on it. Still made 420 hp and 508tq on dyno with that carb and a pretty much stock motor other than balanced rotating assembly, performer intake, and xe 274 cam on 91 pump gas. Either way no issues with it. Let me know if interested.

 

shout out to Jason (oddball) - he spent several hours Saturday going though the 'other' q-jet I had, which came on the worn out sbo350 when I bought car. Turns out that it might have actually been the original carb on my Cutlass....

well it was successful, good idle, no stumbling and at least for now the Holley quest is over.


thank you Jason!

 

Well done Jason

 

For those following along, the other carb is a 7041251.
Idle down tubs were already 0.042", had 1/8" holes in the plates and ~0.05" idle bypass air. All I did was clean it up, put in fresh parts, replace the vacuum break, and drilled out the idle screw holes to 0.1".
Ignition timing was a bit of a mess. It's an HEI, so reset it to 17degree initial and ported vacuum advance. It appeared to be at 30degree initial (!!!!) which I completely didn't notice last time. Amazingly the thing didn't ping at all.
Idles happily at 600 in gear and still jumps off the line.
John, I expect the choke and fast idle will need some tweaking when the weather cools down, and the secondary air spring can always use tuning. That's the fun one to play with.