Author Topic: 1978 454 Quadrajet shuts down.  (Read 937 times)

Offline Jeff K

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1978 454 Quadrajet shuts down.
« on: November 14, 2022, 04:41:21 AM »
 Hello Cliff,  Glad to see your still in the saddle, it's been a long time.

 I bought a 462 with a Turbo 400 from Cliff about ten years ago. I sold the Bonneville and bought a 1969 el Camino SS396 with a stock 1978 454 with around 15,000 miles.  The 1978 454 is stock, untouched and runs very strong.
I bought this car six years ago. I never had any issues with this carb or motor during all those years.     

When I start it cold, it runs good, I hit the gas to lower the cold start rpm. When I put it into reverse to get out of the garage, it will move then stuble like its out of gas and stall but it fires right up after stalling.
It seems to stall when in reverse or making a hard right turn. It runs gerat except of this stalling issue.

Before all this started I adjusted the air / fuel mixture screws for cold weather. I also took some of the bend out of the linkage that opens the choke from the vacuum dashpod, I thought it was too rich.

I adjusted the air fuel mixture screws. They are both around 4 to 4.5

I thought it was a its a bad fuel pump but it fires right up in a split second after stalling.

The cold hit us two days ago so I changed thermostats to a 180 from a 160. I was thinking it was running too cold.

The last time it stalled I could of sworn I heard an electrical spark. It has a stock HEI that looks brand new like the rest of the motor.

Any thoughts?

Thank you..

« Last Edit: November 14, 2022, 04:49:59 AM by Jeff K »

Online quadrajam

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Re: 1978 454 Quadrajet shuts down.
« Reply #1 on: November 14, 2022, 01:20:44 PM »
The engine will flex against the rubber motor mounts one direction in forward, the
other direction in reverse. This could possibly be pulling on the wiring causing  a short
or disconnect. Since you heard it, that would likely be a big wire like a battery cable.
Get it running and start pulling on wires, connectors, cables and see if it stalls. That should
narrow it down. Maybe turn off the garage lights and have someone watch for sparks
while you shift it back and forth holding the brakes. Good luck.

Offline Jeff K

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Re: 1978 454 Quadrajet shuts down.
« Reply #2 on: November 15, 2022, 01:15:50 PM »
Thank you. It was a loose ignition switch connection. I think I'm going to remove the key switch, start and run switching. Then install a nice brass toggle switch and button.
« Last Edit: November 15, 2022, 01:36:48 PM by Jeff K »

Online quadrajam

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Re: 1978 454 Quadrajet shuts down.
« Reply #3 on: November 15, 2022, 02:20:29 PM »
Glad you found it.
Yeah, push button starting is cool!