Currently rebuilding a stock 401 to go into my '34 Buick rod project. What is the minimum size carb I could run on it ? I have a new Holley 600 square bore I picked up at a swap meet some time ago that I was going to use on a Chev 350. Could I run this carb ( I don't have the original ) The 401 will have plenty of power for me so more looking for economy.
My stock 64 401 with 105K miles really likes the Edelbrock 750 CFM carb I installed with electric choke. I have it tuned more for power than ecomony but it gets about 12 mpg around town and 16 mpg on the highway if I am careful with the speed. I went about 2 stages lean from the #1411 carb right out of the box, but I am at about 3000 feet elevation.
I also have an Edelbrock 750cfm man. choke, and right out of the box I does 30mpg at 60mph cruise.. My engine is all stock besides recurved distributor, all in at 2200rpm.. Wouldn't go lower than 750cfm, but would like a Qjet instead if money for a new intake and carb wasn't an issue.. Houmark
That IS good! It'll be no surprise that I like the Q-Jet for just about everything, but for economy it's a fantastic choice. The smaller primaries and precise metering really make it an excellent dual purpose carb. My best MPG was with a 79 Buick 350 carb (800 CFM) coming home from the track - I got an honest 21.5 mpg which I thought was outstanding for 3.23 gears and a 25 inch tire. The same set up ran a 14.57 about an hour earlier, so you see what I mean about dual purpose. As a disclaimer, I have not tried Doc's 3 BBL Holley yet, so maybe 30 MPG is on my horizon too!
In his absence I can say they go very well. My Q-Jet manifold is Doc modded, while it lost .2 tenths to a fully CNC'd plenum, it had (by the seat of my pants anyway) better torque chararistics on the street. I think Tom and I decided it was due to better port velocity at lower RPM's. A ways back I did the Doc Mod comparison back to back with an untouched square bore manifold with the same stock (rejetted) AFB. I cant remember exactly, but I think it was good for almost .2 tenths. I would assume the same would apply to a spread bore manifold.
I was specifically referring to the non Quadrajet manifold having Doc mod. How would it go with the larger butterflies clearing the opening. It would need an adaptor plate made I would think.
I don't have any experience with adapter plates, and I would thing they would screw up airflow, necking down the larger secondaries. I think if you're committed to a square bore manifold, Doc Mod it and go for a large CFM AFB or Holley, maybe with a 1/2 - 1 inch spacer. My AFB ran fine for what it was.
