Thread: Engine stumbles out of slow speed turns

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I have a 350 chevy that tends to stumble a little when making a slow speed turn. I've had 2 different carbs on this engine that idle, accelerate and cruise with no problems, but while accelerating from idle in a low speed turn the engine stumbles a little.

Both carbs were new, I thoroughly checked the float levels and idle mixture on both carbs, but still get the stumble only while turning.

It's a Model A with a Camaro 5 speed!

What's the level in your gas tank, and is it baffled? Fuel pump in the tank or external? Could you be starving your fuel pickup?

Don't think so, tank is full, mechanical pump. I originally thought it was a problem with my idle circuit, but it does it with the new car also.

were is the pickup in the tank ? and is the tank or cap vented ?

Do you have power steering in this car???

iam with Louey on this one. he said that the car has a carburetor , so the fuel bowls will not be running out of fuel just going around a corner. i would check all Grounds or even add some Grounds.

Posi rear end too tight and pulling engine down in turn

I'm thinking along the same lines as Jerry, something is lugging the car down and it is working too hard to overcome that drag. You say you have a 5 speed, what gear ratio in the back? The point I am trying to make is that if you have ever driven a stickshift where you didn't downshift far enough making a turn it will act like what you are describing or even buck. A hot cam will accentuate that even more. In my 27, even with 4:30's and in low gear, it bucks going through parking lots sometimes because of the somewhat radical cam. You could be experiencing something similar.

Don

Originally Posted by vara4

Do you have power steering in this car???

that was my first thought.

It's not lugging, it stumbles as if it's starving for fuel. The car weighs about 2000lbs and will break em loose any gear at almost any speed, even in 5th at 90mph.

Takes off from dead stop with no problems, only stumbles when taking a corner at low speeds from idle, let the clutch out accelerate stumbles then clears up.

I can take off from stand still in all 5 gears no stumble.

What kind of carb(s)? How much fuel pressure? Checked the float levels? What's your idle speed? Too low of an idle can give a stumble before the carb gets into the transistion circuit. Too much or not enough accelerator pump can cause the same stumble.

OK--seems you want to post around mid nite---so tomorrow morning I'll be looking for the following info---

You said its a Model A

What angle is the engine mounted at and what angle is the carb?
What type of manifold?
What type and part number of carb?
Fuel Pressure?
Timing---initial total and curve vacume?
Does the car lean in a turn?
Does it do it turning right and left?
Will it do it if you approach a turn, push in the clutch and let it coast arount the corner?
Does it do it if backing up in reverse and turning?
How much does the engine rock over if you rev it up?and under torque?

I know you said "from idle" but if you take the corner, with your foot in the throttle does it stumble?

i`m with dave .. play with the pump cams and settings .. and maybe hook up your vacuum advance in a dif location or not at all then bump up the timing a few degrees ..

The problem occurs in city driving, approach a busy intersection, shift to 1st or 2nd engine is at idle let out the clutch accelerate engine stumbles then clears up. It smooths out as I come out of the turn, don't know if it's because going straight again or if because rpm's are up.

All I know is it only does it when turning at low speed from idle, period!

It has to be something to do with float level and/or the pump. The odd thing is that it happened with 2 different carbs, both were brand new Holley's.

I checked the float levels twice on the latest carb and they are correct, will try messing with the pump settings/sizes.