Stupid Distributor Questions

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George R

George R

Mopar Nutcase
Joined
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Location
Trumbull, CT
I am looking to replace the stock single point distributor in my 69 340 Dart for an electronic unit. My car is currently all stock, and has a 727 automatic trans with the stock 323 gears, stock AVS carb and factory cam.
I have read of the Mopar Performance electronic conversion kits available, and I'm leaning that way because I THINK it will have the right (or at least close) advance curve built into the distributor out of the box, and also because it should have everything I'll need for the project in the kit.

Will the advance curve in the MP distributor work well for my application?
Is the mechanical advance in the MP distributor adjustable?
Will I need to use a different spark plug after I install the MP kit?
What spark plug wires will I need?

I have also seen electronic conversion kits that are NOT from Mopar Performance. Are these kits primarily used for the elimination of points and to gain the benefits of an electronic ignition without being a performance application?
Is there a difference between a MP conversion kit as opposed to a replacement conversion kit?

Also, if I buy a MP conversion kit, will I need to replace any other parts of the car in order for it to work? I think I remember one of you more experienced members mentioning that the stock mechanical voltage regulator will also need to be replaced, but I don't know why. Would the alternator need to be replaced as well?

My car runs lousy. It pops through the carb occasionally, and I can feel it surge under light load. The distributor that is currently in the car is a generic auto parts replacement for a "non hi performance" application, according to the counterman. I run the vacuum advance off the only available stock port on the carb, and if I disconnect it, the idle speed drops so low it will almost stall, so I assume the factory connected the vacuum advance to manifold vacuum.
Based on what I have experienced with this car so far, I would say the idle timing with the vacuum advance connected is way too far advanced, but with it disconnected, my base timing is at 8º to maybe 10º BTDC. Connecting the vacuum advance again returns the car to the correct idle speed, but the car will ping at higher RPM with my foot to the floor. If I advance the base timing and leave the vacuum advance disconnected permanently, this will create an even higher total timing, and make it ping even more.
I don't want to fool around with this incorrect distributor when it would make much more sense to use an electronic distributor that is for a performance car, and will hopefully have the correct advance curve built into it.
I wish I had the original 340/automatic distributor for the car, but it was gone when I bought the car. I have seen some on eBay advertised as original 340 distributos, but I have no way to verify if they are really 340 distributors or not before I buy them, and I don't want to get burned again. Besides, the prices these sellers are asking for these old parts is enough to make me buy the electronic kit from Dodge.

As always, I am open for any and all suggestions. What would you do if it was your car?

Thanks in advance for taking the time to explain it all to me.

George
 
George,
Popping thru the carb sounds like the float drop is way too low. Can you take a pic of the carb to show us the vacuum port? How are the idle mixture screws set?

In regards to an electronic unit, the plugs stay the same at .035, the curve I believe is about 27-30*(i.e. 8 initial=35-38 total). You could go that route but I would personally fix the carb issue first. The elec. ign will not cure that issue.
 
Changing to the MoPar performance electronic ignition kit is a pretty straight forward installation. The kit comes with very easy to follow directions and it is just a couple splices away from going right in. The distributor right out of the box is usually close enough to just set and forget, but some adjustment is always advised once you get everything in place. The suggestion for all the earlier cars is to also change to the later style voltage regulator, again a 2 splice operation, and if you're feeling really frisky a change from the single field alternator to the dual field style. That involves just adding a second field wire, again not a hard operation. I can tell you that I just did this in my 66 and the performance picked up considerably, especially the voltage regulator change, as the early regulator cannot handle the voltage from the orange box included with the kit. I had the conversion done earlier but did not change the regulator until recently, Boy what a change. I recommend the conversion, especially for the $219.00 it costs. Good luck with your project, Geof
 
redfastback said:
George,
Popping thru the carb sounds like the float drop is way too low. Can you take a pic of the carb to show us the vacuum port? How are the idle mixture screws set?

In regards to an electronic unit, the plugs stay the same at .035, the curve I believe is about 27-30*(i.e. 8 initial=35-38 total). You could go that route but I would personally fix the carb issue first. The elec. ign will not cure that issue.
Click to expand...

Float drop? You mean maybe they're set too low? I can raise the floats a bit to get them parallel with the carb top. I think I remember lowering them in the summer when the car wouldn't start.

I don't have my camera home, it's at work, but the carb is an AVS. There is one large port for the PCV valve, and one small port for the vacuum advance.
There is only one adjustment screw in the center of the carb, and it is a left hand thread screw. It is set about 1 full turn out.

Adam and Cosgig, thanks for the info.

George
 
Check this guy out.I am not running his ignition yet but he is very sharp.I have talked to Don and i think this would be the best system to try and it
will be set up to your application.I have his tuning guide and he is right on.I
will send mine in to him this winter and expect good things.
 
George,
Float level and float drop are two entirely different settings. Float level is done with the airhorn upside down to see how close they are to the airhorn and gasket(usually a carter can be as close as 5/32 up to 7/16) and float drop is done with the airhorn in right side up position. this is to see how far they drop before the needle comes off the seat to allow the bowls to fill again. I like mine set at about 15/16" to 1". set the float level at 7/16" and the float drop at 15/16" and drive the car. be sure to keep the airhorn gasket in place as this is required for an accurate measurement. Do not add in electronic ignition yet, as you need to eliminate variables that exist NOW.

Keep us posted. If you don't understand how to set these specs and you need pics on the adjustments, let us know.

George R said:
Float drop? You mean maybe they're set too low? I can raise the floats a bit to get them parallel with the carb top. I think I remember lowering them in the summer when the car wouldn't start.

I don't have my camera home, it's at work, but the carb is an AVS. There is one large port for the PCV valve, and one small port for the vacuum advance.
There is only one adjustment screw in the center of the carb, and it is a left hand thread screw. It is set about 1 full turn out.

Adam and Cosgig, thanks for the info.

George
Click to expand...
 
The pinging you are describing makes me wonder if the distributor intermidiate shaft is a tooth off....ie car hard to start....pinging under acceleration,bring engine to t.d.c. #1 cylinder and make sure the rotor is pointing to the electrode on the cap....not in between two cylindes on the cap,if it is in between two cylinders the intermidiate shaft needs to be turned a tooth and this should also help the surge under power...it will increase the engines vacume,surge under power usually means a vacume leak but I have seen this same problem with distributor off a tooth,low engine vacume causing vacume advance to act eratic,just check it ...hope this is helpful
 
George, you either need to adjust the vacuum advance canister
[allen wrench through vacuum nipple clockwise takes away/limits
, counter clock wise add's more vac advance]

OR you need to richen the primary side of the carb and/or more pump shot, but like you said without the vac advance hooked up it runs fine so....
Probably limit the vac advance with the allen wrench say 2* at a time.
Good luck.
 
Agreed, you should take care of the carb issue that you have and then look at upgrading your ignition.

Once your carb problem has been straightened out, time your car WITHOUT your vacuum line connected. If you still have a surge issue take care if it before you continue.

Get your timing light and your vacuum gauge out to make final tweaks to your car. If you don't have a vacuum gauge go buy one. As a base you will want to set your timing at 10 btdc, with your vacuum gauge connected, you will want to adjust your idle circuit of your carb to the highest vacuum setting that you can get.

As far as ignition upgrades are concerned I have used the MP conversation units and Pertronix's systems and both are good options. Being that your motor is stock you will probably not notice any difference going with either one. I like the Pertronix unit for some what of a stock look, as it doesn't have an external ECU like the MP unit and is very easy to install.

From there you can time your car to how you want it, either performance or economy.

Performance tip: plug your vacuum port and use a light weight spring to provide a mechanical advance of your distributor.
 
Redfast,
I will look in the service manual tonight after work, but if these procedures are not in the manual, I'm afraid I will not understand how to adjust the drop. I know what needs to be "adjusted" to change the float level, but not what to do for float drop. Thanks for the explaination.

3404speedvaliant,
I played around with a spare vacuum advance can I have using my vacuum pump and it seems to me that the allen adjustment screw didn't change the amount of vacuum advance, it seemed to change the amount of vacuum required to get it to move. Am I wrong?

George
 
George

Save yourself the guesswork on the distributor thing and give Don at FBO a call. Mopar electronic conversion distributor kits are not ready to run out right out of the box. I have one on my Dart and Don had to recurve it and set vacumm advance to my application.

You need to go to his website www.4secondsflat.com and read the tech articles that he has listed where he explains in detail Mopar distributors and how the factory set them up and the changes that need to be made to them to get the best bang for the buck.

Like was said earlier on this thread, he is really knowledgeable and will help you through your issues. Not only with the distributor , but carbureation as well.
 
George R said:
Redfast,
I will look in the service manual tonight after work, but if these procedures are not in the manual, I'm afraid I will not understand how to adjust the drop. I know what needs to be "adjusted" to change the float level, but not what to do for float drop. Thanks for the explaination.

3404speedvaliant,
I played around with a spare vacuum advance can I have using my vacuum pump and it seems to me that the allen adjustment screw didn't change the amount of vacuum advance, it seemed to change the amount of vacuum required to get it to move. Am I wrong?

George
Click to expand...

George,
Float drop is done by bending the little tang at the back of the float. This little piece touches the needle/seat and how much you bend it decides on how much that flat will drop. If you want a pick, I can get one for you. Make sure these settings are correct BEFORE getting into electronic ignition. Not knocking FBO stuff, but why spend money if you don't need to?
If you say your timing is at about 8* or so BTDC, the electronic ignition is not going to solve the surge and backfire issue. That I believe is in the carb. I had the same thing on a car here iwth MSD. under light acceleration it would be fine, but ubder heavy acceleration it would pop, stutter, backfire. THe floats were WAY off. Once reset, car ran great.
 
George R said:
Redfast,
I will look in the service manual tonight after work, but if these procedures are not in the manual, I'm afraid I will not understand how to adjust the drop. I know what needs to be "adjusted" to change the float level, but not what to do for float drop. Thanks for the explaination.

3404speedvaliant,
I played around with a spare vacuum advance can I have using my vacuum pump and it seems to me that the allen adjustment screw didn't change the amount of vacuum advance, it seemed to change the amount of vacuum required to get it to move. Am I wrong?

George
Click to expand...

George, thats just it see your engine only makes so much vacuum so....
it makes sense that the more you tighten the vac advance adjustment the more vacuum would be required to get the full amount so therefore you engines vacuum being only so much can only pull so much against the vac canister spring. thats the idea creating more tension so that engine vacuum can only move the spring so much.
So put away your pump and start checking it with your timing light trial and error.
OK?
 
huh? just turn the distyribtor.

waggin said:
The pinging you are describing makes me wonder if the distributor intermidiate shaft is a tooth off....ie car hard to start....pinging under acceleration,bring engine to t.d.c. #1 cylinder and make sure the rotor is pointing to the electrode on the cap....not in between two cylindes on the cap,if it is in between two cylinders the intermidiate shaft needs to be turned a tooth and this should also help the surge under power...it will increase the engines vacume,surge under power usually means a vacume leak but I have seen this same problem with distributor off a tooth,low engine vacume causing vacume advance to act eratic,just check it ...hope this is helpful
Click to expand...
 
ted_sweet said:
huh? just turn the distyribtor.
Click to expand...

I agree....HUH?????? the reason its in the position that the FSM states is for the boneheads that were in the factory so there was one way to do it. technically speaking for any distributor run car, you can bring it up to #1tdc and drop the distributor anywhere you want. #1 does NOT have to face any exact position. the factory did it so the dealership mechanics and the guys at the factory would have only one way to put things. it also helps with plug wire routing. It has NOTHING to do with one tooth off.
 
Hello George, I`ve been reading up on proper parts for our cars and it is likely your car did come with a single point distributor #2875796. In `69 dual points were reserved for 4 spd. cars.??? With that said, what do your plugs look like? Are they fouled ,appear sooty ,or a nice chocolate brown? Weak spark? Plugs heat range okay? Carburetor leaking down? Those single screw AVS carbs are first generation emission controls, the two idle mixture screws are generally set very lean and then leaded over. The air mixture screw shouldn`t come out much (maybe one turn) to get it dialed in. It sounds like you`re out of the idle circuit with your vacuum advance and tapping into the run circuit of the carb. At idle your carb shouldn`t be pulling that advance in. All of the aftermarket electronic ignitions benefit from a hotter spark, less deviation in spark timing, and eliminating points. The MP electronic ignition is a good system, basically the same thing they came up with in late`71 but it`s proven itself as being relatively accurate and durable. The MP conversion system is set up from the factory so it`ll work in everything from a 273 2 barrel to a hp 340 ,so there`s always room for improvement. They`re set up rather generically. As the guys mentioned a dist. guru (like Don) could replace the springs, dial in both advances, or whatever it takes for optimum performance. It`s recommended to replace the VR as the electronic system is harder on the old regulator. I`m running the original VR with the electronic kit without a problem. There is a new VR that appears old but is filled with solid state internals. If you`re looking for an authentic look that`s a good choice. The MP electronic ignition on my stock `68 340 times out something like 16* initial, 18* mechanical, 16* vacuum advance.
 
Longgone--

Yes, single points for 69 340 with 727.
Plugs look like I put them in yesterday. NO color at all.
I asked the counternam for Autolites for a 69 340. He gave me #65 if I remember right.
Carb leaking down? I don't understand the question. No leaks if thats what you mean.
At idle, I have a LOT of vacuum at the advance.
The center screw is out one full turn, I just checked.
I got a return email from Don @ FBO. He wants almost $400 to set me up with an electronic unit, with the curve set to my car. I can't swing it. No way.
I'll play with it a bit based on you guys recommendations, and report back.
Thanks, guys, for the help.

George

Longgone said:
Hello George, I`ve been reading up on proper parts for our cars and it is likely your car did come with a single point distributor #2875796. In `69 dual points were reserved for 4 spd. cars.??? With that said, what do your plugs look like? Are they fouled ,appear sooty ,or a nice chocolate brown? Weak spark? Plugs heat range okay? Carburetor leaking down? Those single screw AVS carbs are first generation emission controls, the two idle mixture screws are generally set very lean and then leaded over. The air mixture screw shouldn`t come out much (maybe one turn) to get it dialed in. It sounds like you`re out of the idle circuit with your vacuum advance and tapping into the run circuit of the carb. At idle your carb shouldn`t be pulling that advance in. All of the aftermarket electronic ignitions benefit from a hotter spark, less deviation in spark timing, and eliminating points. The MP electronic ignition is a good system, basically the same thing they came up with in late`71 but it`s proven itself as being relatively accurate and durable. The MP conversion system is set up from the factory so it`ll work in everything from a 273 2 barrel to a hp 340 ,so there`s always room for improvement. They`re set up rather generically. As the guys mentioned a dist. guru (like Don) could replace the springs, dial in both advances, or whatever it takes for optimum performance. It`s recommended to replace the VR as the electronic system is harder on the old regulator. I`m running the original VR with the electronic kit without a problem. There is a new VR that appears old but is filled with solid state internals. If you`re looking for an authentic look that`s a good choice. The MP electronic ignition on my stock `68 340 times out something like 16* initial, 18* mechanical, 16* vacuum advance.
Click to expand...
 
If your plugs look like you put them in yesterday (no color on the insulator) you may be running too hot a heat range. I would go at least two ranges cooler which will help your detonation and mixture. The current gas we have now, plus the more powerful ignition can tolerate a much cooler plug.

At idle you should have NO vacuum at the advance if connected per the factory TSM. You should be connected to the timed (passenger side) vacuum port on the carb. If you have vacuum at idle from this port, your throttle plates are too far open to accurately set the idle mixture.
 
Does the car run hot? If not you may be able to run a colder plug. You should start to show some color on your plugs if you`ve run it some now. If they`re too clean you may be running too lean or too hot of a plug. I`m running either 63`s or N9Y Champions in my car and they are a nice chocolate brown. You`ll be okay with the MP electronic ignition as it is from the box. Although there`s always room to dial it in, just installing the electronic will be a great improvement over your single point. Are the idle mixture screws on your carburetor leaded over? If so, they may be set too lean. I do think the throttle plate is not covering the venturi at idle therefore drawing vacuum from the run circuit and increasing idle speed. You may have to back off the idle speed adjustment ,advance the timing, and richen your fuel/air mixture. With that you should be able to position the throttle plate over the vacuum advance orifice. Let us know what you do George.
 
I took so long to post that reply, that C130 Chief said almost the same thing I did.........oh well, but you get the gist.
 
Chief & Longgone--

I can replace the plugs with a #63 easily enough.
The carb questions.....you keep asking about adjustment screws. There is only one screw to adjust, dead center in front of the carb. It is about one full turn out.
The car does not run hot, based on the factory gauge.

Chief,
I will have to play around with the carb a bit to see if I can get the vacuum advance port to stop pulling vacuum at idle. It has a strong signal at idle.
Currently, with the Vacuum Advance disconnected, the idle timing is about 8º BTDC. Once I reconnect the VA, the idle speed goes way up again.
The vacuum advance is connected to the port you describe. There is only one port to use with this carb.
I will post some pictures of the carb tomorrow night.
Thanks for the help guys.

George
 
They`re leaded over on your carb then George, an early emission control. You`ll have to idle the car down some.....about 650 rpm , to see if you can get the throttle plates in the carb to shut enough to close off the orifice to that vacuum advance tubing port.
 
No way!
Yep, my carb has the lead plugs. I gotta get those off there. My idle is crappy too. I need to richen up the carb a bit.
Off to work, chat later, and THANKS guys.

George
 
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