Skip the auto shop - Our mechanics make house calls

Q: Swapped carburetor and the engine stalls out.

asked by on

Hi, I need some help. I have a 1973 350 Chevy motor which had an old Edelbrock 4 barrel carb. that hesitated and backfired a lot. I found a rebuilt 1973 Rodchester Quadra-jet for a good price, so I swapped out carbs. The Q-jet starts her and idles her smooth and strong, but the second I try to put it into gear she kills, even when allowed to fully warm up. The other carb. would let it run in gear once warm. Plus, I get a double whammy when she dies hot. Hedder heat retards my starter even with a shield wrap. Then it won’t start until she’s cool again. There’s no idiot lights and I can’t scan for check engine codes because this motor was dropped into a 1982 El Camino and I don’t think any of that was set up. Any suggestions to make run in gear would be greatly appreciated. She’s what gets me to work and back daily-(was). Thanks in advance, Tom

Hi there. When you swap out carburetors on engines, you would have to set up the carburetor and adjust the float bowl along with setting the idle. With a Rodchester Quadra-jet, you would need to have the engine idle at 850 to 950 rpm’s in the park and neutral positions and 650 to 750 rpm’s in the drive or reverse position. Also, when changing out the carburetor, the timing will need to be adjusted with an advance. This is for the massive air jets when snap throttling the Rodchester Quadra-jet. Plus, make sure that all of the ports to the carburetor that are not used is plugged off if there is a vacuum on the port. If you need further assistance with adjusting your carburetor to keep the engine from stalling, then seek out a professional, such as one from Your Mechanic, to help you.

Was this answer helpful?

Need advice from certified mechanic? Get help now!

Over 1000 mechanics are ready to answer your question.
The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details

Ask a Mechanic
(100% Free)

Have a car question? Get free advice from our top-rated mechanics.

Ask A Mechanic
Over 10,000 questions answered!
  1. Home
  2. Questions
  3. Swapped carburetor and the engine stalls out.

Get an instant quote for your car

Our certified mechanics come to you ・Backed by 12-month, 12,000-mile guarantee・Fair and transparent pricing

Get a quote

What others are asking

Q: My engine and exhaust are pulsing when my car is at idle.

Without knowing the exact setup done with the new carburetors I would suspect there is a carburetor setup issue and may need adjustments to the idle jets sizes since it may be running too lean or too rich at idle....

Q: 2005 saturn relay does it have a fuel filter

Start by checking for spark and fuel. If all fuses are good, possible causes can be a bad fuel pump if no fuel pressure is found at the injector rail. Also, it could be a bad ignition coil or bad...

Q: Advice on how to find the exhaust manifold leak

The first thing to do is check it when the engine is cold. When it is cold the metal shrinks and if it is leaking, it will leak more. Also, since it's cold you can feel around with your hands....

Related articles

P0240 OBD-II Trouble Code: Turbocharger Boost Sensor B Circuit Range/Performance
P0240 code definition Turbocharger Boost Sensor B Circuit Range/Performance What the P0240 code means P0240 is an OBD-II generic code triggered when the Engine Control Module (ECM) detects the intake boost...
How Much Does a Mechanic Make in Vermont?
Automotive technician jobs in Vermont have an average mechanic salary of $37k, with some mechanics earning a salary of $53k.
P2103 OBD-II Trouble Code: Throttle Actuator Control Motor Circuit High
P2103 means there is a fault with the throttle actuator control motor circuit, likely due to a defective electrical component or part.