I need a new dash pot and idle stop solenoid for my Motorcraft 2150 2bbl carb. on my 351M (1979 F100 w/ cc and AC). I cannot find one anywhere? Everywhere I look, they are obsolete. Does anyone know where to find one of these that is new besides Ebay?

 

They are still available. Advance Auto carries the following manufacturers:

Standard:
Idle stop solenoid: ES45
Dashpot: D541F

Niehoff:
Idle stop solenoid: FS3657
Dashpot: FS400

These part numbers all came off of their website. I found them by entering your vehicle information. These are pretty low-volume items, so you'll probably have to have them ordered for you. They're not cheap. Standard Motor Products tends to be a little better quality, but Niehoff is usually cheaper.

Advance's website: http://www.partsamerica.com/

One final note - sometimes these pieces are combined as one unit, and sometimes not. It'd be nice if you could see these before buying them to make sure you're getting an exact replacement, to make sure they go together like the originals. Unfortunately, they don't list pictures online for these particular items, but if you have a local Advance Auto, they could help you out. Napa is another store to try. Hope that helps.

 

Tried them, they are now obsolete despite the fact they are still shown on the web site and in the catalogs. I have also check Auto Zone, Napa, Nation Parts Depot (NPD), Dennis Carpenter, LMC Truck, and Ford/Motorcraft suppliers like Sumner Automotive. No one has them anymore?

 

Sorry to hear that, I should have checked further. When it comes to this stuff, your final try is to talk to Pony Carburetors. However, with stuff this late into the 70's it's hit or miss. But it's worth a shot: http://www.ponycarburetors.com/

If you can't find what you're looking for through eBay or a junkyard, your last option is to try and do without. If you can tune your curb idle by the regular curb idle screw without the truck dieseling when you shut it off, you can do away with the idle stop solenoid. That doesn't always work, but you may get lucky. Sometimes you can get away without the dash pot as well. It's to keep the motor from stalling when you let off the gas really quickly. Often times if your throttle return spring is "soft" enough, you can do without.

 

I thought the solenoid also adjusted the idle of the engine when the A/C is engaged? When I turn my A/C on, the engine RPM drop about 50-75rpm. I thought the idle solenoid compensated for the RPM loss and bumped the RPM up while the A/C is on? Currently my truck runs at too low an RPM when the A/C is on. I have adjusted the idle up to about 550rpm with the A/C off in drive. If I bump it up anymore, the truck will be running too high an RPM with the A/C off. It is either too high or too low, the solenoid should account for the extra load on the engine?

 

The solenoid has nothing to do with AC, despite anything you have read or been told. Later model trucks do have such a mechanism, but it is not the case on a '79. The purpose of the idle stop solenoid is to prevent dieseling. On many carbureted engines, the curb idle is set by a screw. This holds the throttle plates open slightly. However, on smog engines that tend to run hot, this gives way to dieseling ("run on") when you shut the truck off. Hot spots in the combustion chamber act like glow plugs and the slight opening of the throttle plates by the curb idle screw allow a path for air, and hence fuel to enter. This is why some older motors bang around a bit after you shut the key off.

The idle stop solenoid fixes this. On your carburetor, the curb idle screw is not responsible for curb idle. The idle stop solenoid is instead what controls things. When the key is turned to ON, the solenoid is energized, and a plunger extends which holds open the throttle. When you cut the key, the solenoid is de-entergized, the plunger retracts, and the throttle plates are allowed to shut completely. Because there is no path for air to enter the combustion chamber, the motor cannot diesel as long as it is free of vacuum leaks. That's what the idle stop solenoid does: it keeps the throttle plates open slightly at idle while the motor is running, and lets them shut completely when the motor is off. On these carburetors, the curb idle speed is controlled by moving the solenoid forward and back via a long worm screw.

Again, the idle solenoid has nothing to do with AC on this vintage of carburetors. The reason your idle drops when you turn on AC is because the AC compressor clutch engages and introduces more load onto the engine. There is no mechanism on your engine to increase RPM when the AC is on, from the factory. You can, however buy aftermarket solenoid kits for this from Edelbrock, but any time you look up "idle stop solenoid" as a replacement part for your engine, it's going to be the part I just described.

 

I knew that the solenoid prevented the engine from dieseling, but I was not sure about whether or not it played a part in the AC. It sucks that there is nothing you can do about the A/C pulling too much power other than holding your foot on the gas when idling. I doubt you had to do that when the truck(s) were new so I have no idea why I need to now. Like I said, with the A/C off, it idles perfect; maybe even a little higher than recommended so I could help account for the A/C. Any ideas why it is pulling my RPM's down so much? (all A/C parts including the clutch are new) (I am using the original tecumseh compressor not a york)

 

How are your mixture screws? Each should be at about 1.5 to 2 turns out, pretty evenly. Ideally, you should tune your idle mixture with a vacuum gauge, to achieve maximum vacuum at idle. With your mixture set correctly, you will be able to tolerate a 50-75 RPM drop in idle. The reason I bring this up is because a 50-75 RPM drop shouldn't affect your idle that much, when tuned properly. This is why I suspect your idle may be a bit rich or lean. It'd be in your best interest to check your timing as well. My point is, a properly tuned engine should be able to idle down to 500 RPM without stalling.

 

I have adj. the two mixture screws but that did not seem to help. My carb is old and only the power valve and fuel pump have been replaced. I am starting to think the carb needs rebuilding. The mixture screws seem to do nothing for it.

 

If adjusting the mixture screws has no effect on how the motor idles, that's a pretty strong indicator of a vacuum leak. While the motor is idling, you can try spraying a can of carb cleaner around suspect areas (vacuum lines, carburetor base, power brake booster, etc) and listening for a jump in idle which tells you that spot is leaking. Turning each mixture screw 1-2 turns in either direction should cause a noticeable change in the engine's idle. If that's not what you're seeing, you most likely have a vacuum leak or varnish in the carburetor's idle circuit.

 

I have checked every vacuum line and port on the entire truck and everything is perfect. If I do have a leak, I have no idea where it is coming from. I will check the vacuum lines in the dash for the A/C / Heater controls since these are hard to get to and see. I have checked them as well as I could but not thoroughly. Thank you for the advice, I will try a few things and see what I come up with.

 

D8AZ9S514D .. Control Assembly-Vacuum Break (Motorcraft CK2057)

KINSEL L/M in Beaumont TX has FOUR = 800-816-2894

BOB ALLEN FORD in Overland Park KS has THREE = 800-676-0675

HENRYETTA FORD in Henryetta OK has THREE = 800-922-3673

GREEN SALES COMPANY in Cincinnati OH has 35 = 800-543-4959

WESLEY OBSOLETE PARTS in Liberty KY has TWO = 606-787-5293.

There are more, but this oughtta do it.
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D9SZ9S520A .. Dashpot & Solenoid Assembly (Motorcraft CD40)

CADILLAC OF HICKORY NC has TWO.

That's it...no one else has any.

Take the Motorcraft numbers to NAPA, they can cross them over to the brands they sell.

 

Thank you for all this information. I found the solenoid at NAPA but the dash pot is extinct. Cadillac of Hickory went belly up so if they did have/had it, who knows where it is now? Thank you again for the contact info.

 

Is the dashpot electric? Parts catalog also shows on that isn't.

 

Dentside, I realized this thread is kinda old and I know you don't have your truck anymore from reading on the other site. I hope you're getting better everyday. But did the solenoid you got from NAPA help with raising the rpms with the AC on? I don't want to just up the idle, because then it would be way to fast in park without the AC on.