Ok guys - I've thought I had the correct carb on my car, but now I'm thinking the contrary. A long-time Olds mechanic who works on my car noticed an extra bracket on the carb and didn't think it was proper. And now a guy who rebuilds tri-power carbs looked up my carb id in an AC Delco parts book and said my quad was for a full sized car (not a mid-sized car).

So, what is the proper Rochester 4 bbl carburetor for a 1970 Cutlass with 350 cid and automatic transmission?

 

7040250
but, others can be made to work properly.


bill

 

What numbers are on your carb. The tech area at the top of top CO banner has an OE carb listing by year. If you want to replace your carb, other may be interested in it.

Adam

 

Thanks for reminding me of that resource. I've referenced other resources as well (to include the FAQ section of 442.com) and most point to a 7040250. However, how would you read this? 7040250 or 7040255.jpg

The row for 7040250 indicates "Exc. Cutlass". I believe that to mean "except". Therefore, I would think a carb with that id is for a big body car. And the 7040255 would be proper.

So, what is correct?

 

my info comes from the delco number 9 book, it's the bible in that regard.


bill

 

It's a miss-print. 7040250 is what's listed in my chassis servise manual for the non W31 350 4bbl.

 

I've been wondering the same thing. I have a 71 cutlass supreme with a 350 4bbl. I ran my carb numbers and it said it was for a 455. I know its original carb.. I thought it was a factory error, but must be a misprint instead lol. Are these carbs sucking 750 cfm?

 

they can move up to 750 cfm, the actual amount is determined by the individual engine. the secondary air valves act to "customize" the carb. to the engine's needs.


bill

 

Just to confirm what others have said:
A 1970 Cutlass with a 4 bbl 350 came from the factory with the 7040250 quadrajet. That's straight from the Engine Assembly Manual, not a service manual.