[sglemans]

71 350 2-bbl
Is it possible to hear pinging when its at idle, or only under acceleration? I'm getting a sound that resembles engine pinging but i'm starting to think it might be exhaust related. Could a slightly leaking exhaust near the front cause a similar sound? I can sometimes hear it when its at fast idle as well, but it always does it when i accelerate about halfway or more into the pedal.

[steve25]

Before you drive the car again warm it up some and at idle with the vacuum advance unhooked and plugged off confirm with a timing light that you have no more then 12 to 15 degrees of initial timing showing up.

If you do then the mechanical advance section of the distributor is at fault and hanging up .

You do not want to drive a vehicle in that condition.

[sglemans]

Forgot to mention I also get a hiccup/bog when I get over halfway into the gas pedal. A bit worse when it's cold but still always does it. P

[steve25]

Sounds to me like your whole issue resides within the carb, or atleast 95% of it.

The first thing to check is the amount of accelerator pump shot you have.

Run the motor until it’s warmed up and then shut it down and check what you see in the primary’s when you work the throttle.

With 1/16” movement of the lever you should see a small shot of fuel that with further open of the throttle along with fast movement of doing that grows into a high pressure stream that disperses onto the booster cluster in each primary bore.

If this does not take place then the carb needs to be rebuilt.
It also needs to be fully soaked in carb cleaner and blown out with high pressure air.

Besides your accelerator pump possibly not working right I also think your primary metering rod piston is hanging up due to residual garbage from today’s fuel.

What I posted here assumes that
Your fuel pump is good.

Your fuel filter is clean.

You carbs float is good.

Here’s two basic carved in stone rules of thumb for problems directly related to carbs.

1)
If the motor is hesitating Surging up and down in rpm, and or coughing back through itself at any point in the throttle opening then the issue is due to not enough fuel getting into the motor along with the air that’s getting driven into it.
2)
If the motor just does not respond well to throttle application, but none of the above conditions take place then the carb is running rich.
This could be something as simple as the choke still being closed, or closing off as the throttle is opened .

Rich running is easy to spot by looking at the plugs and if sever enough will be smelling rich out the exh along with some black smoke possibly.

Also check that all of your vacuum hoses are connected tight to there nipple and that they are not dry rotted.

Another source for a lean stumble is that your vacuum advance can is bad and that then would be a source of a vacuum leak.

[sglemans]

Steve25, thx for that info.
It does a lot of surging when it's first driven, and a couple of times the bog caused it to stall. This after I warmed it up for 5 minutes even in the summer.
Once it's warmed up, it's more like a short hiccup when pressing the gas, , even when you are already moving. Always when you are halfway into the gas pedal. Feels kind of like it would when downshifting the trans. Also makes that ringing sound from the pass side I mentioned whenever you accelerate, still can't tell if it's pinging or something else.

I looked for the squirt when it was cold, and I could see gas squirting into the carb when I pull the throttle.

[steve25]

A ringing sound from the passenger side tells me that the warm up flap in the exh manifold is slapping open and closed in response to cylinders that are not firing right at times.

If you have some mechanics wire or solid copper or aluminum wire you can strip out then you can tie that flap open once the motor is cold and at least eliminate that noise.

In fact if your thermal control spring in that exh manifold might be part of your overall drivability issue besides what sounds like a carb issue.

[sglemans]

Where is this exhaust flap located?
I had a feeling it might be exhaust related but it's so hard to pinpoint.

[Stuart]

Originally Posted by sglemans

Where is this exhaust flap located?

It's right at the exit of the passenger side exhaust manifold, where it connects to the exhaust pipe. If you look down on the passenger side of the engine you should be able to see a counterweight and coil spring on the manifold, when the engine is cold you can reach down there and move the counterweight.

This is a picture of an earlier 389ci engine but the arrangement should be similar.

[sglemans]

Is there a way to tell if it's working correctly, especially when cold?

[Stuart]

If you can move it, and the spring isn't broken, it's likely working. Having said that, it's not uncommon for them to get rusty so they stick and won't move, and/or the spring breaks.

[steve25]

I thinks his moves, but his spring is shot or gone.

[sglemans]

Might be a bit buried under all the ac stuff if it's in that spot, I will def. give it a look thx

[steve25]

You have aT37 with AC?
I thought that was not a optionon that stripped down model.

[sglemans]

Yeah, it has lots of options, 350, AC, front disk brakes, carpeting, vinyl roof, wheel well moldings

[sglemans]

Too bad that valve thingy is not on the drivers side like the Olds I just had. Much easier to reach

I'm guessing it's in the middle, since that's where the pipe is attached to the manifold?

[steve25]

With a car fitted with ac you will have to get at it from under the car.