I posted the photos of the D/Dart carb spacer on the 771 intake that is on my car. It is not tapered and looks like it was rough machined.

A little rant.... I hate reading 273 builds. Even though there is a reason a person is building a 273 motor for their car, everyone says to throw the little 273 away and put a stroked 360 in the car. And then they describe the 360 build that you "should" do. Arg.

Anyways...my D/Dart ran a best of 12.95 at 105 back in 66 while competing in D/S. Nationally, it wasn't competitive. The engine was blueprinted, as all engines were back then. It had the, as delivered in the trunk, Doug's headers on it. I believe they were 1 3/4" with 2 1/2" collectors back then. They used 7" M&H A140 slicks mounted on 4 1/2" rims -- wow --- and ran 5.33 gears. I'm not sure what they launched at but they shifted and ran through the traps at 6800-7000 RPM's. And don't forget the rosin burnouts.....for traction.