I have a 77 bird with the 403 olds rochester 4bbl carb that is not passing California smog because of high CO. The smog tech believes that the carburetor is the source of the problem. Should i have someone rebuild the carb or should i buy aftermarket like Holley. I'm not looking to go all out, i just want a reliable replacement. what are your suggestions on the best bang for my buck??


Ive used you guys several times before and like the results, so Im glad you guys are here

IMO I would go with the Holley carb. New is always better than rebuilt, and they don't call the stock carb the infamous Quadrajunk for nothing!! Dave.

I've always likes the Q-jet. If the car runs & drives okay I dont think I would buy a replacement. I would want to keep it original. Check around with some repair shops and see if anyone has a EGA (Exhaust Gas Analyzer). You can stick it up the tail pipe and adjust the cars mixture screws in the front to maybe get the CO down. You might ask whoever failed the car what level is acceptable so you know what it needs to be.

Hey, howz everything in good old Fresno? Lived there for 3 years on Huntington, I believe that was the name of the street or boulevard as it was called.

I don't care for the Holly Spreadbore replacement. Have had way too many of those things, they don't meter as well and tend to warp. If not the metering plate, then the base warps and pulls the screws out--just check the number of replacement and fixit parts for the thing and that should be the clue.

The stock q-jet is a nice carb and it is easy to adjust, if you know how and here's how (this is a must to pass SMOG).

1. If your carb has a solenoid controlled idle, disconnect the lead to the solenoid.
2. Set the idle using the idle speed screw to 750 rpm in neutral, for both manual and auto.
3. Screw in the two idle air adjustment screws in the base all the way in--lightly set them, do not torque those puppies in, just turn until a slight resistance can be felt.
4. Back out the idle air screws to 4.5 turns exactly.
5. Turn on the engine and reset the idle to 750 rpm using the idle adjustment screw on the throttle linkage.
6. Using a vacuum gauge, set the idle to the highest rpm and the best vacuum that is possible, by either screwing out or in each idle air adjustment screw the exact same amount. If you lose track, start over again.
7. Now, here's the trick (the next couple of steps)...once the highest idle speed is obtained, with the best vacuum possible, reset the idle to 750 rpm by using the idle speed adjustment screw on the throttle linkage. Check the vacuum, and make any fine adjustments using the idle air adjustment screws--turn them in or out a very small amount as needed if at all, and then reset the idle to 750 rpm.
8. Here's the last step and this is for SMOG passage---once 750 rpm is obtained and this is the best possible idle quality, then turn in the idle air adjustment screws (turn them in towards the carb--clockwise) to obtain a 50 rpm drop in idle speed--turn in both screws an equal amount. This is called "The Lean Roll" and is a very important step for passing the SMOG test.
9. Reset the idle speed back to 750 rpm using the idle adjustment screw at the throttle linkage.
10. Reconnect the idle solenoid.

OK, here's the rub, the engine will run just fine with this final adjustment, but if you want it to run at its best, then after the SMOG test is passed, then turn the idle air adjustment screws back out the same amount and reset the idle. It sounds complicated, but it isn't--this is right from the factory manual and the steps should be followed exactly.

Also, remember to double check the float level--if it is too high, that will also mess up the test.

Hope this will help your engine to pass. If not, then the carb should be rebuilt by a pro. There are several on the Internet that can do the job. They can re-color the original gold, and replace the throttle blades and pivots as well as give you a clue as to which main jets/rods should be installed for your engine. Also, I recommend that you replace the 2ndary metering rods with the AX size and make sure that the 2ndar throttle blades are opening up fully--they should open to over center for full air flow. Believe it or not...the factory actually closed off the 2ndary side (by not letting the throttle blades open up fully) to restrict hp back in the 70's and deliberately choked off the fuel flow by using 2ndary metering needles that were too large.

That was very insitefull. I'm glad to see somebody who offers step by step instructions to help

Thanks for the tips everyone. I gonna try the instructions that "Me Too" provided, and if it doesnt work, i will hand it over to Smith's Autoparts to send it of to Los Angeles for the rebuild.

Let us know how it works out

Hey thanks again for the advice... Due to time constraints and the lack of a reliable tach, i took my bird to a local mechanic who made the adjustments for me. My bird is flying again!!!!! 44 dollars to turn a couple screws and it is running cleaner than the average car! suck a fat one California Smog Standards.

next step... suspension!