Hey Guys,

Today on my way home from work the throttle stuck momentarily on my '71. The RPM's shot up quite high (I have no idea how high as I was more concerned with getting the pedal to unstick) and a plume of smoke came out of the exhaust pipe. After that the car seemed to run okay until I got off the highway. At the stoplights the engine kept dying. I was able to crank it over by giving it some gas and keeping the RPM's up, but as soon as I let off the accelerator it would shut off.

Any ideas?

Thanks,

Mike

Pull the valve cover and check for loose rocker arms, broken valve springs, or obvious bent valves. Pull the spark plugs and check their condition. Do a compression check.

What type carbs?

Why did the throttle stick?

What color was the plume of smoke?

Carbs been rebuilt?

Daily driver?

Smell like fuel?

Sounds like it's running out of gas?

History on the car?

Answer all the above questions and then continue posting;)

Pull the valve cover and check for loose rocker arms, broken valve springs, or obvious bent valves. Pull the spark plugs and check their condition. Do a compression check.

...and what he said

You have bent some valves. If the car runs at higher rpm's but dies under say....2500 rpm, it is an indication that you have several bent valves. Run a compression check to confirm this.

What he said.

Run a differential compression check and you will know WHICH valves you have bent.

What type carbs?

Why did the throttle stick?

What color was the plume of smoke?

Carbs been rebuilt?

Daily driver?

Smell like fuel?

Sounds like it's running out of gas?

History on the car?

Answer all the above questions and then continue posting;)

Twin SU type carbs.

The carpet caused the throttle to stick.

The plume of smoke was white.

I've owned the car for about a year now, I can only say that I haven't rebuilt them. I don't know if the previous owner had.

I'd say the car is a daily driver during the nice months of the year on days with good weather.

No fuel smell.

Doesn't really sound like it is running out of gas, just dies at low RPM.

As previoulsy stated, I've only owned the car for a year so I don't know much if any history on it. It has always run well for me.

Thanks for all the replies. I will check the compression tomorrow after work and will report back.

Mike

If it was blowing white smoke, you may have blown your head gasket. White smoke is the result of coolant being burned. Once again, a differential compression test will tell you where your problem lies.

Can someone explain how a differential compression check differs from a compression check? I've never heard of this term before.

Thanks,

Mike

He might just mean comparing the cylinder pressure readings between cylinders. It's more important than the actual pressures. All cylinders should create the same pressure, within ~20-25% lowest compared to highest according to the FSM and the Monroe rebuild book (although most people recommend a tighter number). For example, I've had two engines that tested within 2 psi, high to low, at about 175 psi for one and 180 psi for the other. The gauge used will affect the pressure measured though so the comparison is what's important.

If you do find a pressure imbalance, a leak-down test would then give you more information about whether it's the head gasket, the rings or the valves.

If you have a bent valve in a cylinder, it'll probably read "0".