Idle solenoid - do I need it?

[Tazinhawaii]

Hi all, new to Mopars (older ones at least) and have done a bunch of searching.  I have a 71 Cuda 440+6.  It has the idle control solenoid, but trying to figure out if it's needed on an automatic car.  Most things I've found reference it used on 4 speed cars.  Also, what is it supposed to do?

Thanks,
Derrick

[73_Cuda_4_Me]

Idle solenoid comes on with key, and sets throttle plates at slightly open position for idle air/fuel mixture. When is shut off, idle solenoid retracts, letting throttle plates close completely, preventing "dieseling", where car keeps sputtering after key is off (heat in engine is enough to ignite an air fuel mixture in intake). By closing off throttle plates, less air can enter intake, so air/fuel mix won't self-ignite.

Do you need a solenoid? Depends if you get dieseling after turning engine off... usually slightly modded engines won't need it... disconnected vacuum advance, bigger cam, different intake, larger valves, etc...

Only one way to find out....  8  )

[anlauto]

Is that an original V code six pack car ?  It's beautiful

[DocMel]

I was under the assumption that the idle selenoid was only used on A/C equipped cars: When the A/C was turned on, the seleniod engaged to keep the base idle up when the additional work of the AC compressor pulled on the engine.  In the AC case, it is important to have to keep the idle up, especially with an auto trans, or the engine would stumble at the low idle once the AC compressor engaged

I have run many holley six pack, tri powers (GM speak) and they were all sticks with no AC , and no idle selenoid was needed

[Tazinhawaii]

Thanks.  I have it installed (precious owner installed it), but the set screw set to not actually touch the plunger.  I haven't had any dieseling so I think I'll leave it alone.

And, no, unfortunately it's not an original V code car.  But that's why I didn't spend 6 figures for it.  I have a $55K budget and I'm pretty close now.  I just got the car down on the ground this morning and waiting on the touch-n-go start system to arrive Monday.  Then I'll be able to drive it around the neighborhood at least...

The last thing I need to figure out is the reverse switch in the trans.  For some reason it's making contact between the outer posts of the switch when in reverse.  More studying on that topic now...

Derrick

[Chryco Psycho]

Still a wicked car 

[Tazinhawaii]

So I'm starting the tuning of the 6 pack.  Installed a Wideband O2 today.  Idle settings had it pegged lean (>19).  Tried adjusting the center carb to richen it, but couldn't get anything less than 19.  Then started richening the forward carb and PRESTO!  Idles 13.5-14.5.  Debating if I want to turn the front card idle mixtures back in a little and swap front with rear and adjust again with what is now the front carb (previously rear).  That should get all 3 carbs doing their part.  Or maybe just leave it as it's now idling better than it ever has with no popping and so forth.  I did find that the throttle of the center carb doesn't close all the way.  It gets stuck slightly open unless I push it the rest of the way.  Probably why the previous owner had what I consider a "HULK only" return spring on the throttle.  I think tomorrow I'll pull the center carb and try to unstickify the throttle.  From past driving, I think the full throttle setup is pretty close as is, so hopefully no adjustments there will be required...

Derrick

Will add pictures of the car as it is now later.

[Chryco Psycho]

It could be a number of reasons why the enter carb is hanging open  ,  gasket  fast idle cam , linkage to outboard carbs etc  I usually trun he idle srew out approx 1/2 turn & use the center carb for final adjustment but swapping end carbs will work too .