Engine Is Racing

[Hotroddoc]

i'm helping my friend who has a 66 Mustang with a 289 engine and has an aftermarket intake manifold with a Holley carb. Before he put it away a year and a half ago, he noted that the engine would race uncontrollably. Starting it up this year, same problem.

The linkage is working normally (nothing sticking). We noticed he had a vacuum leak on the manifold that we fixed.

Does anyone have any ideas what could be going on? I do not recall if it has an electric fuel pump.

Thanks,

Gary

 

[afast93stang]

My 67 did that until i figured out that a spark plug boot had worked its way loose enough to affect the idle and i had tuned it unknowingly based on 7 cylinders firing which caused the engine to race. Once that plug was fixed i redid the tune and it was fine.