Carburetor Idle Stop Solenoid Configuration

[340inabbody]

Does anyone have a picture or drawing of a Chrysler Carburetor Idle Stop Solenoid and how its mounted with a bracket? I’ve never seen one and would to make one as close how Chrysler did it. I am running a Holley DP 650. So I don’t need a nos or repro factory set up. Buy I have no clue what they look like and how they mounted.
Thanks much guys!

 

[340inabbody]

Ok I think I can close this one out myself. The geometry thats needed is not dependent on the model car or anything other than the type of carburetor. I can probably just use this below as I have seen this on other Holley 4150’s. This is my plan and should work fine or at worse case a minor tweak to the bracket.

 

[Newbomb Turk]

Why do you think you need that?

 

[340inabbody]

Why do you think you need that?

I may not. It’s a bit complicated but as you may or may not know, I’m using the progression programmable distributor. And it’s made a world of difference. I am able to get fine point tuning that I could never get with a regular distributor that I needed. In any event, I’m having some slight dieseling while also and also some hard starting. I can probably tune for it, which is what I’m trying to do right now.
I could explain what I’m doing with the distributor, but it’s fairly long. But essentially I am able to have a smoother transition from park to in gear. So the difference in and out of gear is like 200 RPM. I just might need to back off some timing at the low end.

 

[str12-340]

following - have the same problem in one of my cars. The original Mopar carb had such a set up, but the aftermarket replacement doesn't. Briefly, do you understand how it works?

 

[RustyRatRod]

I have one on the 400 in Gladys, but I use it as an A/C idle up solenoid.

 

[MV8]

340inabody, an "idle stop" is what it is. It is a plunger that extends when power is applied to raise the idle to compensate for the rpm drop from the AC load and is adjustable. Not going to help you prevent dieseling/run-on. Timing adjustment and/or fuel quality will help with that.

Some carbs have a solenoid that stops fuel flow when the ignition is shut off but those carbs are tiny and would never be used on something like this. There is no easy way to instantly stop flow from the bowl unless the carb was designed for it.

 

[RustyRatRod]

340inabody, an "idle stop" is what it is. It is a plunger that extends when power is applied to raise the idle to compensate for the rpm drop from the AC load and is adjustable. Not going to help you prevent dieseling/run-on. Timing adjustment and/or fuel quality will help with that.

Some carbs have a solenoid that stops fuel flow when the ignition is shut off but those carbs are tiny and would never be used on something like this. There is no easy way to instantly stop flow from the bowl unless the carb was designed for it.

It could if he adjusts it right. If he adjusts it so the idle is correct with the solenoid on then when the ignition is turned off, the solenoid will fall and close the throttle blades further and might aid in engine run on. Something he won't know for sure until he tries it. Usually though, engine run on is caused by retarded timing. With initial timing too far retarded, the engine has to be idled up too far and that's normally when one runs on.

 

[mbaird]

I run one on the 408 in my Swinger . I use it as a choke for cold starts . It mounts to the base plate on my Pro Systems carb and I wired to a 120 degree thermal switch that breaks the connection once it reaches 120. Works great !
I will try to get a pic in next few days .

 

[YY1]

I've seen solenoids designed to throw the throttle wide open on ignition shut off to stop dieseling/run on.

 

[Newbomb Turk]

I may not. It’s a bit complicated but as you may or may not know, I’m using the progression programmable distributor. And it’s made a world of difference. I am able to get fine point tuning that I could never get with a regular distributor that I needed. In any event, I’m having some slight dieseling while also and also some hard starting. I can probably tune for it, which is what I’m trying to do right now.
I could explain what I’m doing with the distributor, but it’s fairly long. But essentially I am able to have a smoother transition from park to in gear. So the difference in and out of gear is like 200 RPM. I just might need to back off some timing at the low end.

Got it. If it’s pump gas there are other things you can do to stop run on.

If your CR is between 10-11:1 you can use a 180 thermostat. Sometimes just a 10 degree or so temperature drop can eliminate or at least reduce it some so other measures can get rid of it.


I’ve also used a standard reach plug before to get the tip of the plug closer to the cooler chamber wall. You might need 1-2 degrees more timing.

One range colder plug can help. That’s only if the plug you have is on the warm side.

Edit: you have a 200 rpm drop going into gear which is real nice. What is your idle rpm? Sometimes a 75-100 rpm reduction at idle can help that too.

You might need to use a combination of those things to clean that up.

 

[340inabbody]

Thanks for your inputs guys. I believe the issue is timing and carburetor adjustment. As it wasn’t doing this before as I started the tuning process. Thought it might help me but I know I have some more tuning options still on the table. This Progression Distributor has an infinite amount of tuning capability.

It is stranging that I am having both a hard start condition AND dieseling. Both minor however

 

[340inabbody]

Got it. If it’s pump gas there are other things you can do to stop run on.

If your CR is between 10-11:1 you can use a 180 thermostat. Sometimes just a 10 degree or so temperature drop can eliminate or at least reduce it some so other measures can get rid of it.


I’ve also used a standard reach plug before to get the tip of the plug closer to the cooler chamber wall. You might need 1-2 degrees more timing.

One range colder plug can help. That’s only if the plug you have is on the warm side.

Edit: you have a 200 rpm drop going into gear which is real nice. What is your idle rpm? Sometimes a 75-100 rpm reduction at idle can help that too.

You might need to use a combination of those things to clean that up.

Thanks I had Autolite 63 64 and 65’s to play with. Currently running the hotter 65 but thats a bormal heat range plug if I am not mistaken. Idle is a bit high at 1000 RPM but she likes it there.

 

[340inabbody]

I thought that too much timing would cause dieseling not being to retarded. This isn’t intuitive. Can someone explain how being too retarded could cause it?

 

[Newbomb Turk]

I thought that too much timing would cause dieseling not being to retarded. This isn’t intuitive. Can someone explain how being too retarded could cause it?

Retarded timing causes excess heat in the chamber and really all the way out of the exhaust port.

That heat can cause run on.

I had a customer helping his friend with a Comp Eliminator car and they had really high EGT’s after some other tuner worked on it.

So they called me and asked what I thought. So the first thing I asked was plug heat range, timing and jet sizes.

They kept adding jet and pulling timing out and the EGT’s kept climbing

They were down to 24 total timing and they had enough jet in it for 250 more HP.

I told them back to the tune up before the tune up.

That was 10-12 jet sizes smaller and 32 total and watch the EGT’s go back down. And they did.

The point is late timing plus all that excess fuel wasn’t done burning before the exhaust valve opened.

So you get some combustion still going on past EVO. Hence the high EGT’s.

 

[67Dart273]

340inabody, an "idle stop" is what it is. It is a plunger that extends when power is applied to raise the idle to compensate for the rpm drop from the AC load and is adjustable. Not going to help you prevent dieseling/run-on. Timing adjustment and/or fuel quality will help with that.

Some carbs have a solenoid that stops fuel flow when the ignition is shut off but those carbs are tiny and would never be used on something like this. There is no easy way to instantly stop flow from the bowl unless the carb was designed for it.

diesel run on is EXACTLY what some were used for. My 70 "non CA" 440-6 RR had one. This had no retard distributor, Prestolite dual point, and did not have evap gas tank, either.

OP: Some idle solenoids WILL NOT engage until the throttle is "bumped." That is, if it's idling at some speed and you energize the solenoid, some applications do not provide the "oomph" to raise the idle until the pedal is moved a bit. I think maybe the ones for AC use were able to bump the idle, and don't which didn't or why