TenMidgets

'71 455 w/ E heads and performance cam, runs great. However when I start it after sitting for a night and pump the gas liberally a couple of times it then stalls. Not sure why cause if I don't do that and go right into gear, its fine. Could it be a tricky fuel pump perhaps?

I'm not an expert so wanted to see if its something that can be diagnosed and a minor fix done so I can feel comfortable when revving it so it won't stall?

Thanks,
Bill

ah64pilot

Are you revving it before it warms up? What kind of carburetor do you have?

MDchanic

So first you depress the gas pedal to set the choke, then you start it, then you "depress the gas liberally," which to me means you floor it?

Why?

You never rev or accelerate quickly with a cold engine. It's not good for it.
Also, it won't run smoothly or allow the secondaries to open until its had at least a few minutes to warm up.

Please give us more details.

- Eric

TenMidgets

I suppose I am. But its different than my other Cutlass engines in that when it starts it revs/idles high and then normalizes after a few min but sounds like it could stall easily. My carb is a Quadrajet 4bbl.

I do not floor it, by liberally I meant about halfway to the floor. Its possible I am not letting it warm up enough..how many min is necessary? I just find it strange that if I even tap on the gas pedal lightly during the warm up process it stalls every time.

Lady72nRob71

If it stalls, there is a problem. Sounds like it is running lean during cold startup. Check for vacuum leaks and correct choke adjustment. Do you know the high-idle RPMs? After it warms up does it run okay?

TenMidgets

Not exactly sure on the rpm's cause the gauge doesn't work too well. As long as I don't give it gas after it turns over runs fine once I put it in gear. I've learned to pump it a couple times then start it and stay off the gas at that point.

Lady72nRob71

Are both fast idles working?
One pump cold will set the choke and set the fastest idle speed. After starting, idle may be like 2500RPM. I gentle nudge on the pedal should bring the idle down to around 1200. After a few minutes when warm, another slight pedal nudge should drop it to normal idle, around 700.
This is how yours should act. If not, we need to find out what is missing...

TenMidgets

Thanks Rob. I agree that how it should act, but once I get the initial 2500ish RPM after starting, any gentle nudge or contact with the gas pedal will stall the engine. I've basically just been waiting a few minutes and then put it into gear and go. It never stalls when I do that, but it does seem to run a bit sluggish until I press the gas deliberately...say halfway.

I'm a novice w/ engines and never had a performance cam, so I may take it to my mechanic to look over.

frankr442

The thermostat could be opening too quickly, so that when you move the linkage it drops past the cam steps before the engine can idle at a low RPM.

TenMidgets

Really studied the situation this morning and I think this car just needs more warm up time than others I've had. After giving it a good ten min to run then I touch the pedal and it idles down as it should. From there it runs like a top so I suppose its not a huge deal, just have to be patient!

SBORule

Well, atleast now you know it's a choke issue.