The q-jet uses what is called a spread bore, which is what you have described. This was the stock carb for the sbc for ages. It's a good carb for milage and operating medium performance engines. The other carbs use what is called a square bore pattern, all 4 holes are the same size.
For carb info go to
www.carburetion.com For V8 casting numbers go to
www.mortec.com
