Hi everyone I am having an issue with my 440, it appears the previous owner put in a huge lift and duration cam which i have no idea about . The car only idles at 1250 RPM, anything lower and it stauls. The heads are indy pro heads, the cars goes like hell but because of the high idle, i get run on when I turn it off, any ideas.

 

You might want to put this thread in the 70-74 engine section. You will more than likely get more advice/responses

What mods are done to the motor? I'm don't know to much about cams, but I can give you a website that might help you out. I would probably put a less radical cam in.

http://www.hughesengines.com/general...icleID=1000013

 

I'm guessing by "run on when I turn it off", you mean detonation? It keeps running - like it doesn't want to shut off?
If so, I had a similar problem with a previous car of mine. The 1978 Mustang Turbo I had suffered terribly from detonation (it wouldn't shut down right away when turned off). I solved that with a simple (and fairly inexpensive) water injection kit. This is a common problem with forced induction cars. But my guess is in this case, the timing has been advanced or retarded so much because of the lift and duration of the cam that you're getting a similar situation - unspent fuel left in the cylinders when you turn it off, so it keeps "choking and kicking" after the key is turned off.
My guess is without changinging anything internally to your motor, you could solve the problem with a water injection kit. It worked in my situation, was inexpensive, and was easy to install.

 

Three things that help a high lift/ high duration camed motor: Higher compression pistons, higher stall converter, larger fuel tank.

As far as the run-on, my next question would be do you have sugnificant power drainage from your battery if the car sits for a few days? Your ingnition system my be getting some voltage when shut off (rare, but does happen). The one time I saw this it was a wiring problem from the alternator.

 

Oh, get someone to double check your ignition timing for you. The best guys to do it are drag racers (no offence roundy roundy guys).

 

I am not sure of the make/year/model, but when I built my 440 for my 71 Road Runner, I used a Holley carb that had a fast idle solenoid mounted on the throttle arm shaft. When the ignition was switched on, it pressed on the throttle arm and opened it slightly. When the ignition was turned off, the solenoid would retract slightly and prevent run on. Also, I used an MSD ignition, which helped a lot with driveability and smoothness and holding the 'tune'. Good luck.

 

I just moved it.