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Just converted to Electronic Ignition, can't get rid of ping

ozbie

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I just installed a SUM-850005 electronic ignition kit in my '70 RR 440+6. I can't seem to get rid of a slight ping when accelerating hard, when I set my timing anywhere below 10btd the car runs like crap, seems to run well at around 12-15btd but get a slight ping when I hit it. Any ideas would be appreciated. Thanks
 
What is the total advance curve of your distributor? If you have a stock distributor they are usually around 25 degrees mechanical so that puts you at 40 total degrees timing when your at 15btd at idle. Are you using a timing light to set the total timing as well? You need to recurve the distributor so it will let you run 15 degrees or so at idle but total stays at 34-36. That can be done if you have an adjustable distributor or if you have a stocker, you can use the FBO limiter plate which works well or file the slots which is kind of a lost art and time consuming. I run the plate on my 360 in my PowerWagon and it works very well and is simple to install.

fbo-mopar-distributor-limiter-plate-19.gif
 
I'm not sure what the total advance is as it's hard to read, they do say in the instructions to start initial timing at 5 and lower as needed. I might add that I'm not using vacuum advance, also i'm using the stock ballast not the kit ballast.
Here's the kit
SUM-850005_xl.jpg
 
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Well I just talked to Summit Racing and they said I would need to connect my vacuum advance to get rid of the ping (it's adjustable)...so I guess i'm going to go back to points as my metering block (on the center carb) doesn't support vacuum advance...anybody want to buy a slightly used electronic ignition?
 
Wait wait wait that makes zero sense. Total timing can be adjusted as long as you know how to curve the distributor to your desired liking. Vacuum advance should not be added until you get your total curve figured out. That should be your first thing you figure out is your total timing. Vacuum advance is only going to add timing at cruise and part throttle so that has almost no bearing on what your issue is at the moment. Your issue is total timing in the distributor.
 
You don’t need to run points.
I don’t use vacuum advance on mine.
You need to know your total advance timing. Usually around 34-36.
Also knowing cylinder pressure and fuel octane would help.

(I recurved my distributor to start timing at 22 degrees and total timing at 38 degrees with no vacuum advance).
My cranking cylinder pressure is 185 so I run 110 octane to prevent pinging at these settings.
Every engine is different so it will take some time to see what is right for you.
 
Also carb tuning will have an effect on timing and pinging as well.
 
I don't have a tach and no scale on the balancer...but I'll try to take a guess on total timing. I've been adjusting the carbs as I change the timing based on, manifold vacuum, idle speed (guesstimate) and idle smoothness. I'm not sure this distributor can be "recurved", I'll have to do some additional research.
 
You don’t need to run points.
I don’t use vacuum advance on mine.
You need to know your total advance timing. Usually around 34-36.
Also knowing cylinder pressure and fuel octane would help.

(I recurved my distributor to start timing at 22 degrees and total timing at 38 degrees with no vacuum advance).
My cranking cylinder pressure is 185 so I run 110 octane to prevent pinging at these settings.
Every engine is different so it will take some time to see what is right for you.

I am with him.....running points isn't your issue at all. If anything going back to points is going backwards unless your looking for a 100% correct resto. It is all in the distributor. The timing plate must be adjusted to limit the total curve, giving you the ability to keep your initial timing higher while limiting the total timing.
 
I don't have a tach and no scale on the balancer...but I'll try to take a guess on total timing. I've been adjusting the carbs as I change the timing based on, manifold vacuum, idle speed (guesstimate) and idle smoothness. I'm not sure this distributor can be "recurved", I'll have to do some additional research.


That plate I sent you a pic of can be added to any Electronic Chrysler distributor. If you have a timing light with a dial setting on it, you can dial in the timing you want total and use the zero marker on the balancer. That is what I do. Without knowing your timing numbers, you are basically guessing and without getting lucky you'll be out of the ballpark. Something like this light is worth its weight in gold!

Image57__34962.1375297176.480.400.jpg
 
I don't have a tach and no scale on the balancer...but I'll try to take a guess on total timing. I've been adjusting the carbs as I change the timing based on, manifold vacuum, idle speed (guesstimate) and idle smoothness. I'm not sure this distributor can be "recurved", I'll have to do some additional research.

There is timing tape that can be added to your balancer to check total timing. The distributor has springs to determine rate of increasing timing and slots to limit total timing these all can be changed or modified. If you have a good shop near you they can compare your stock distributor curve to your new curve if they have a distributor machine. If this wasn't happening with the stock curve then you could change the new curve to match what you had.
 
Thanks for the great feedback, I just purchased an adjustable timing light (amazon), I will check the adjustability of this distributor, if needed the limiter plate seems like a likely option, I see Mancini sells these.
This should be fun!
 
“This should be fun”

The most important thing to remember!
 
those mopar distributors have 26 degrees in them and then you add 15 which would give 41 total. that ain't going to work.
 
So rt boy 67....what do you not agree with? Just curious?
 
those mopar distributors have 26 degrees in them and then you add 15 which would give 41 total. that ain't going to work.

You mean adding with the vacuum advance correct?
 
Anywhere above 15 degrees I get lots of pinging, anywhere below 15 degrees I get a slight ping that doesn't appear to go away upon lowering the timing. The engine runs like crap (hard acceleration) if I use the starting 5 degree recommendation (carbs adjusted). Do you know what is the recommended (optimum) total timing should be?
 
If I recall correctly, we usually shoot for a baseline total timing advance of about 36 degrees, all in above 2200RPM, on a mostly stock engine, correct?
That's a good place to start. Whatever the initial timing is from there should be around 10-12BTDC with a purely stock distributor IIRC.
The above is with vacuum advance disconnected, of course.
 
Anywhere above 15 degrees I get lots of pinging, anywhere below 15 degrees I get a slight ping that doesn't appear to go away upon lowering the timing. The engine runs like crap (hard acceleration) if I use the starting 5 degree recommendation (carbs adjusted). Do you know what is the recommended (optimum) total timing should be?

Most 440's will want somewhere between 34 and 36 total timing. Any more and you may see a small increase in power, but thats a safe number to start with for sure.
 
Most 440's will want somewhere between 34 and 36 total timing. Any more and you may see a small increase in power, but thats a safe number to start with for sure.
Yessir, that's where mine is now and I'm running the electronic Mopar setup (orange box).
I don't use vacuum advance at all, since it makes mine run all wonky. I know, I need to adjust it with the little allen wrench, just haven't fooled with it.

What color box are you running, ozbie? It matters.
 
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