Motor shutters at Idel.

[blue69runner]

So now the motor is back together and fired it up. The hydraulic lifters rattled a little then quitted down. It seems to shutter back and forth. Like a rough ideal but it take fuel and rpms go up but when letting off at idle again it starts to shake some. I don't remember it doing this before. Thought it was smooth running. Any thoughts. Sounds like maybe something in the passenger side bank. Oh, it is a 383 Motor.

 

[DanielSlocum]

Hows the balance? internal? external? drastic change in piston weight?

 

[Mick56]

I would start with a compression check.

 

[Don Frelier]

Did you double check the firing order?

You can pull one plug wire at a time and see if the idle gets worse. If no change then there is something wrong with that cylinder.

 

[eldubb440]

possible turn of an idle/air screw?.....

 

[blue69runner]

It did sit for three months without running while waiting for the new head to be done. Changed the oil and filter. I will check all the above. It is like what else. Thanks, everyone. Blue

 

[MWbirdLOVER70]

Vaccum leak?

 

[PRHeads]

I’m on board with the compression test.

But before I did that, I’d try and borrow(if you don’t have one) an infrared heat gun and check the exhaust temps.

 

[Don Frelier]

Could just be a bad plug (Autolite for example)
Shaking is usually more than one cylinder mis-firing or not firing.