Chevy 350 Runs Rough and quits!

[AltonR]

My 85 5.7 litre Cobalt still runs better timed at 12+ degrees BTDC than at 8 or 10 degrees before TDC. With either setting it will eventually stall. Engine starting fluid sprayed around carb base did not indicate a vacume leak. Has new plugs, plug wires, eletronic ignition and recent carb overhall. Can anyone help?

 

[Bondo]

Re: Chevy 350 Runs Rough and quits!

With either setting it will eventually stall.

Ayuh,... When it Quits,.... Is it lacking Fuel, or Fire,..??

 

[180shabah]

Re: Chevy 350 Runs Rough and quits!

Ayuh,... When it Quits,.... Is it lacking Fuel, or Fire,..??

After we determine the above, we will need to know what we are working on. 5.7L and the boat manufacturer is not enough information. Exactly which engine and drive do you have.

 

[AltonR]

Re: Chevy 350 Runs Rough and quits!

Plugs foul and are wet when pulled. Could be weak spark.

 

[MikDee]

Re: Chevy 350 Runs Rough and quits!

My 85 5.7 litre Cobalt still runs better timed at 12+ degrees BTDC than at 8 or 10 degrees before TDC. With either setting it will eventually stall. Engine starting fluid sprayed around carb base did not indicate a vacume leak. Has new plugs, plug wires, eletronic ignition and recent carb overhall. Can anyone help?

I would suspect this, it sounds like the float is set too high, or it's sticking. Or the idle circuit is messed up, something is amiss here. Wet plugs are an indication. A vacuum leak would usually cause a fast idle.

 

[JJJ]

Re: Chevy 350 Runs Rough and quits!

If the engine or timing chain is original, it is possible there is getting to be excessive slop in the timing chain.
It is fairly easy to check, pull the distributor cap and turn the crank one direction, stop, then reverse direction and see how many degrees it takes for the dist. rotor to start to turn the other direction.

 

[AltonR]

Re: Chevy 350 Runs Rough and quits!

After we determine the above, we will need to know what we are working on. 5.7L and the boat manufacturer is not enough information. Exactly which engine and drive do you have.

1985 Cobalt with OMC 800 out drive and 600 hours on engine. Will start fine but runs rougher as it warms. Seems to load up like rich fuel mixture then quits.

 

[Bondo]

Re: Chevy 350 Runs Rough and quits!

Will start fine but runs rougher as it warms. Seems to load up like rich fuel mixture then quits.

Ayuh,... Fix the Carb...

 

[MikDee]

Re: Chevy 350 Runs Rough and quits!

If the engine or timing chain is original, it is possible there is getting to be excessive slop in the timing chain.
It is fairly easy to check, pull the distributor cap and turn the crank one direction, stop, then reverse direction and see how many degrees it takes for the dist. rotor to start to turn the other direction.

This is not advisable on a boat, because you could damage the water pump impeller in the drive, which is always engaged as the engine turns.

 

[AltonR]

Re: Chevy 350 Runs Rough and quits!

This is not advisable on a boat, because you could damage the water pump impeller in the drive, which is always engaged as the engine turns.

Problem turned out to be the Quadrajet Carburator was flooding the engine at idle and fouling the plugs. I'm replacing the Rochester with an Edlebrock 750 new. Thanks to all members who gave input!! Rich

 

[MikDee]

Re: Chevy 350 Runs Rough and quits!

Glad you got it figured out, but isn't that carb a bit big for a stock 350? I would think a 600cfm would be better, Anyway good luck, Mike