I need to replace my carburetor. My Cutlass currently has # 7040253 and being that's going to be hard to find, could one of our experts offer a replacement brand or source? I do not need anything for racing, just something that will last for a while and not interfere with the fitment of my W31 air cleaner.

 

Your car would have come stock with a 7028251 or 7028253 if a Cutlass or 4-4-2. I think it may have had a 7028255 if it was a W-31 from the factory. Others will know for sure on the W-31 carb.

 

I would first make certain the carb needs to be replaced and not just rebuilt.

 

x2

 

Some "expert" advice:
Are you sure it's toast?
Always better in most cases to rebuild the OEM. If it's a true # matching carb for a 68 W31, DO NOT, I repeat DO NOT TURN IT IN FOR A CORE. Rebuild it or put it on a shelf and get a replacement. Keep it with the car.
Several rebuild services will make it like new again. Google it.
Cliffs is one rebuild service. Call him dont text or email, he likes to talk to you, though he will return emails.

https://cliffshighperformance.com/
https://quadrajetpower.com/oldsmobile-quadrajets/
https://www.thepartsplaceinc.com/par.../&keyword=carb
https://www.sparkyscarbs.com/
https://jetchip.com/product-category...d-restoration/
https://quadrajetparts.com/quadrajet...-c-128_33.html

No QJ will run 100% out of the box. In fact, no carb will run 100% out of the box. They all need to be calibrated to your engine. Do a little research on QJ rebuilding and rebuilding services as well as tunning.

An Edelbrock 1900 series is a good alternative....BUT it too will need to be tuned to your application as will your timing curve (timing curve is as important as carb tuning they go hand in hand).
https://www.edelbrock.com/shop/carbu..._list_limit=30

The bottom line is if this is a true W car the best recommendation I have is to refresh the OEM QJ.

 

Thanks a million for all of the communication. I'm the second owner of this car and I've had it about 40 years. At some point, the W31 components were added. It does have the performance cam, M20 transmission, no AC, and manual brakes. It was ordered like this as I also have the original bill of sale and original invoice. I was fortunate enough to save a bunch of '68 invoices from the dumpster many years ago. The carb has been rebuilt a couple of times and even with an old technician trying multiple times, it will not idle. I do know better than to get rid of this core as I believe it fits a '70 model. An OE carb would be my choice, but that is probably not in my budget.

 

Check out cliffshighperformance.com. Either repair it yourself, or send it to him. Sounds like the idle tubes need to be removed, and the passages in the carb body cleaned out. Cliff Ruggles also has an excellent book. Unless it's been run over or badly corroded, it should be able to be repaired

 

the OE 4 barrel carb for a 68 Cutlass would be a 7028250 but any 68 carb 251,253 ,255 ect. would work and be physically correct and if re-jetted will run fine and not that expensive or impossible to find ,don't give up on finding a 68 carb

 

The 7040253 has an integral choke (the round housing on the passenger side of the carb). The correct 1968 carb used a divorced choke (choke coil in a sheet metal housing bolted to the intake manifold). I'm guessing that you have the incorrect carb because the intake has been changed, correct?

 

I do believe the intake was changed also Joe. This car would have came with a 350 2bbl set-up. Thanks for the information. I probably need to find an OE 4bbl intake to set it close to being original along with the correct carburetor.

 

What's the best vacuum signal you can achieve by simultaneously adjusting timing and A/F mix?
Points or aftermarket distributor?

 

If it won't idle and considering the age there is a good chance the base is worn where the throttle shafts go through. When it is running spray some carb cleaner or starting fluid on the base and see if it smooths out momentarily. If it does that is your problem. There are bushing kits to fix this or you can have it rebuilt.

 

Thanks Glenn,
I'm going to try some of the suggestions from everyone this weekend. Your advise is appreciated.
Troy

 

7028250 if it was a Cutlass.

They didn’t start using a 7928253 until very late in 68 and only in 400’s. I’ve only seen a picture of 2 of them in my lifetime. 7028251’s were used in both 455’s and 400’s for the entire production year regardless of whether they were MT or auto’s.