I'm rebuilding the quadrajet for my 1969 442. It's a 7029251. The engine is pure stock so I plan to keep the jets, rods etc. all original. Now the problem. A previous owner removed the main air bleed inserts from the air horn leaving me with about a .125 upper main air bleed. I'm not sure what size opening it's supposed to have, but I know that wide open is not correct. Does anyone know what size a 7029251 should have?Thanks in advance.

 

I’ll apologize in advance, I don’t have info on that particular carb but I’ll check some notes on carbs I’ve worked on so that you’ll have an idea of range. If nobody nails it for you with accurate & relevant info, I’ll see if I have some more info on such things tomorrow when I get out to the garage.

……….………………..…….Stock……………..…Mod ……………...…Stock …….……..Mod . . . . . . . . .. Stock
………………….…………….SBO ……….…….434 SBO………..…….BBO…….…..……SBO . . . . . . . . . . BBO
……………………………..7041250…….…..7040258……….…..7043252……….7042250 . . . . . . .7040251

45* on Venturi leg -. .049 . . . .. .. .070 . . . . . . . . .. .042 . . . . .. .042 . . . . . . . . . . .. .040

Next to tapered ….... .040 . . . .. .. .053(stk.047) .. .. .040 . . . . .. .055(stk040) . . . . .. .040
Head screws

So, it looks like .040” is the size.

​​​​​​…..

 

Thanks for checking, bccan. In my collection of carburetors, I have a 7028251 Q-jet from a 1968 442 and it has .040" upper air bleed inserts as well. It looks like that was the "go to" size for a bunch of Oldsmobile quadrajets in those days. I'd love to be able to ask Oldsmobile's engineers why they went with the jet/ rod/ bleed combos they chose, but it all worked, so I'll go with it.

Thanks, again

 

Contact Cliff Ruggles. There are bushings available you can press in & redrill to size.