ok, so when its ideling it runs SMooth as a baby's but.. but when i give it some gas, it starts shaking, and vibrating the car, as i go down the highway, feel likes the tires are very badly balanced, but when i let off the pedal... it smooths out the ride... im thinking ive got soem dead cylinders, so i figured ide buy some cheap o spark plugs to see if i can fix a dead one or too, temporarly, until i do a full tune up.
*note this engine has 200,000 miles, and was rebuilt with original bore only 40,000 miles ago, its got to last me till i get my 355 built :/

If your at Idle it really is smooth?
How mant RPM's do you have to turn to create the problem? will it do it in neutral or park by reving the motor to a specified RPM?

If it has a miss at idle start the motor when its completely cold wet your finger and touch each header tube if you find a cold one thats the missing cyclinder, squirt bottle works well too, you can do it with amanifolds as well but you've got to be fast
Miss after idle sounds like fuel loss, air leak in fuel line, bad pump?
What was the car doing when it started missing?



[This message has been edited by Mwilson (edited January 15, 2005).]

Make sure your ignition system is in good shape with no burnt wires or boots. We had a guy on the dyno yesterday that had a similar problem that turned out to be 2 burnt spark plug boots. Cost him about 25 rwhp.

Yeah, unless you've got some dirt in the carb's main ciruits a miss-under-load is usually ignition-related.

I had a fuel pump leaking internally once that would idle smooth, the higher i reved it the worse it ran,
I had i dry rotted fuel line back at the tank that would idle smooth, the higher i reved it the worse it ran,
One time my pick up coil somehow messed up and the car would turn about 3500 and die i could hold it to the floor and it was like i shut the car off? I replaced everything you can think of before finding that

the fuel pump and carb are only 40,000 miles old, and its been running fine untill just this week, it gets up to about 1500 then runs roughly. im about to tinker with it now.

I had a similar problem and it was a broken tranny mount! Take a look at that before you dig deeper.

Are you sayin its missin or just shaking?

does it do it in neutral at a dead stop if you raise the RPM's gradually is there a point where it just starts missing?
or is it a shake/vibration that is'nt noticable at idle and gets progressivly worse with RPM's?

it shakes the whole car, and runs like crap, but i figured it out, a peice of the carb broke and fell into the engine, and probably killed a valve, or sparkplug or somethen... i havent pulled the plugs yet, but thats on my to do list sunday morning.

A piece of the CARB broke off?? That's not something that happens every day! What piece? If it caused actual mechanical damage you would think it would run rough all the time. Maybe you got lucky and it just banged one of the spark plug gaps almost closed. That'll cause symptoms like you describe.

Topic: rough running engine when given throttle?

a peice of the carb broke and fell into the engine

When you say 'give it the throttle' we didn't think it meant in a literal sense.

<font face="Arial,Verdana" size="2">Originally posted by onovakind67:
Topic: rough running engine when given throttle?

a peice of the carb broke and fell into the engine

When you say 'give it the throttle' we didn't think it meant in a literal sense.</font>
Yeah thats cute!

yeah a peice of the casting, like a suport for the center stud hole broke off, and fell down inside.