1990 p30 454 with carb running rich

[esslinger5]

Anybody know where to locate the fuel adjustment on the carb?
Thanks

[Chevelle427]

What type carb
If holly
Jets are in metering block
But just starting to run rich could be flooding prob
If so there is an adjuster on top for the flote on top of bowel (2)
holly bad about any trash can make needle not seal all way
Could be a dead cylinder maybe a bad plug or wire

Iv not had a holly just start to run rich without help

[esslinger5]

There has been lots of tinkering with the motor so I'm sure that helped. But plugs and wires are all new and all cylinders have compression

[Chevelle427]

Fyi re check wires BBC will run on 7 cyl
Firing ordere
18436572
To find
Num 1 cyl
rotor button points towards frt motor driver side that is number 1 cyl
Then just ck firing order
If motor has had work and someone trying to hop it up and this was an ongoing issue carb could be too big (cfm) or jets to large
Jets are not hard to change just have to test and tune

[Charlie 5320]

Originally Posted by esslinger5

There has been lots of tinkering with the motor so I'm sure that helped. But plugs and wires are all new and all cylinders have compression

Won't have a Holley on it unless somebody put it on there. They had Quadrajets on them from the factory. Bout the only adjustment on a Quadrajet is for the choke pull off. If it's a Quadrajet and running rich, most likely the needle and seat in the carb or the well plugs are leaking bad. Either way, a rebuild may be in order. Trying to find a guy that knows Quadrajets in this day and age may be pretty tuff to do. Is it hard to start after it sits for a few days or only after a few minutes. If both, that is a sign of leaking well plugs.

[LETMGROW]

IF you have a Quadrajet carb. you could also have a bad float. Most of these carbs used composite floats which have a coating on them to seal the porous composite material. After time the sealer has a tendency to crack and gas will penetrate the float and add weight to it. This will hold the float down into the bowl and allow fuel to seep past the needle causing the carb to run rich.
Composite floats are not repairable but are generally priced under $15.
Some of these carbs had brass floats. I have seen these develop a crack in the solder joint where the top and bottom halves of the float are put together. They can be repaired but it is tricky. Replacements should be readily available. About the same price as composite.
There should be a number stamped on the side of the carb. vertically which will start out with 170******. This number is the best reference to use when buying parts for these carbs. The number will be on the driver's side rear of the float bowl.
I have a set of float level gauges which can be used by inserting one into the air horn while the engine is idling. By reading the level I can tell if the float level is correct without removing the carb. top. If the level is too low I know the float is fuel soaked and needs replacement.
If someone has tried to do some mods for performance on a Q-jet they may have tampered with the primary metering rack adjustment. In the center of the front of the carb base you will see a plug staked into place if the adjustment hasn't been tampered with. There are NO specs anywhere for this adjustment. It was set at the factory with a flow bench and should never be touched. If it has been I would junk the carb. You will never get the carb to work correctly.
I started working on Q-jet carbs in the fall of 1965 when they appeared on the 1966 Olds Toronado and other 4 bbl. Olds engines among other GM lines. Corvette started using Q-jets in 1965 if I remember correctly. I was working in an Olds / Cadillac dealership back then and attended several factory schools including the Rochester school which was in the same building as the GM training center which served our district.
If I had the carb part number I'd be happy to help you find parts if you need help.
Lynn