318 vacuum advance

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Mattyb

Mattyb

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Hi I have a stock 1969 318 in my Dart. My issue is I just replaced the distributor with a new one from Autozone, and when I hook up the vac advance anything over idle it pops out the exhaust. I disconnect it runs great. I’ve tried all different timing with no results, I am running a msd box with a factory dodge electronic distributor . Any help is appreciated.
 
Mattyb said:
Hi I have a stock 1969 318 in my Dart. My issue is I just replaced the distributor with a new one from Autozone, and when I hook up the vac advance anything over idle it pops out the exhaust. I disconnect it runs great. I’ve tried all different timing with no results, I am running a msd box with a factory dodge electronic distributor . Any help is appreciated.
Click to expand...
OK. lets start at the begining.
What timing is it set at now?
Chrysler had many different advance curves and timing specs. Basically a different one for every engine combination.
So whatever you got from AZ is likely different (internally) than what you removed. Do you know anything more about either distributor?

Second, lets go over setting the initial timing.
First the vacuum advance should be disconnected and the hose from the distributor plugged with a golf tee. (Or equivalent)
Second. Set the initial timing at as low of an rpm as you can get it to idle. Write that rpm down. Depending on the distributor you got, it may or may not already be advancing.
Third, reconnect the vacuum advance. Timing should not change if the engine is at slow idle. Or if there is some vacuum advance added, it should be only a couple degrees.
 
Last edited:
double check your firing order...maybe a wire crossed....? Thats if you had pulled the wires. I have seen where the wires are crossed, car idles fine but pops when throttled usually out of the carb tough. exhaust seems like it could still be possible.

basically start with checking the easy stuff...:)`
 
Mattax said:
OK. lets start at the begining.
What timing is it set at now?
Chrysler had many different advance curves and timing specs. Basically a different one for every engine combination.
So whatever you got from AZ is likely different (internally) than what you removed. Do you know anything more about either distributor?

Second, lets go over setting the initial timing.
First the vacuum advance should be disconnected and the hose from the distributor plugged with a golf tee. (Or equivalent)
Second. Set the initial timing at as low of an rpm as you can get it to idle. Write that rpm down. Depending on the distributor you got, it may or may not already be advancing.
Third, reconnect the vacuum advance. Timing should not change if the engine is at slow idle. Or if there is some vacuum advance added, it should be only a couple degrees.
Click to expand...
Mattax said:
OK. lets start at the begining.
What timing is it set at now?
Chrysler had many different advance curves and timing specs. Basically a different one for every engine combination.
So whatever you got from AZ is likely different (internally) than what you removed. Do you know anything more about either distributor?

Second, lets go over setting the initial timing.
First the vacuum advance should be disconnected and the hose from the distributor plugged with a golf tee. (Or equivalent)
Second. Set the initial timing at as low of an rpm as you can get it to idle. Write that rpm down. Depending on the distributor you got, it may or may not already be advancing.
Third, reconnect the vacuum advance. Timing should not change if the engine is at slow idle. Or if there is some vacuum advance added, it should be only a couple degrees.
Click to expand...
The distributor is for a 1978 ram charger with a 318, timing was set at 0 per manual for the motor. Always timed engine with vac advance disconnected and plugged.
 
Mattyb said:
distributor is for a 1978 ram charger with a 318
Click to expand...
Which one? The one in the car or the one removed?
Mattyb said:
timing was set at 0 per manual for the motor.
Click to expand...
What rpm did you set the initial at?

I assume you mean the '69 Dodge Shop manual spec for 318 with Clean Air System.
The distributor you have, if it really is to specs for a '78 truck, is probably set more like a non-CAS.
Parts store distributors are sortof one size fits most so lets not count on that being 100% like the oriignal '78 ramcharger.

Mattyb said:
Always timed engine with vac advance disconnected and plugged.
Click to expand...
Great!
 
Guess my thinking is this, only one thing was changed, the distributor.
So even though popping in the exhaust is unburned fuel, it seems best to begin with the item changed.
Spark plug wires, or magnetic pickup wires reversed are certainly both possibilities.
Reversing magnetic pickup is easy with an MSD (except for the 6C with the chrysler plug).
 
Mattax said:
Which one? The one in the car or the one removed?

What rpm did you set the initial at?

I assume you mean the '69 Dodge Shop manual spec for 318 with Clean Air System.
The distributor you have, if it really is to specs for a '78 truck, is probably set more like a non-CAS.
Parts store distributors are sortof one size fits most so lets not count on that being 100% like the oriignal '78 ramcharger.


Great!
Click to expand...
I agree 100% one fits all, yes I used the 1969 shop manual I’ve tried all different timing positions with same results. I’m assuming I’m going to have to mess with the springs in the distributor. One other thing it’s a 2 barrel engine and have the vac line in the pass side of the carb, thanks for your help
 
Mattyb said:
I agree 100% one fits all, yes I used the 1969 shop manual I’ve tried all different timing positions with same results. I’m assuming I’m going to have to mess with the springs in the distributor. One other thing it’s a 2 barrel engine and have the vac line in the pass side of the carb, thanks for your help
Click to expand...
Well double check the pickup wires. I don't know how you made the connection to the MSD. I've done it a few different ways. Definately easy to get them switched up since its not a plug in.

I don't think you'll have to mess with the spring tension. At least we dont have information pointing that way yet.

From what you describe the vac port connection seems correct. We can check that.
 
Mattax said:
Well double check the pickup wires. I don't know how you made the connection to the MSD. I've done it a few different ways. Definately easy to get them switched up since its not a plug in.

I don't think you'll have to mess with the spring tension. At least we dont have information pointing that way yet.

From what you describe the vac port connection seems correct. We can check that.
Click to expand...
I have the factory electronic ignition connectors from the msd to the distributor which already came with the connector
 
Mattyb said:
I have the factory electronic ignition connectors from the msd to the distributor which already came with the connector
Click to expand...
They have a plug in adapter? That's nice. Got pic?

Ive always had to adapt something or use the crappy squeeze splices.
Original instructions assumed squeeze splice and leaving the electronic harness in pluce but unplugged (as a backup).
upload_2021-8-18_13-33-15.png

Not all Chrysler pickups use black and orange. Someplace I have a list of the other color codes used.
 
Why RPM of initial can be important.

Lets say we have the original distributor for '69 Dodge 318.
We set the initial timing to be TDC at 700 rpm.
Below 700 rpm, the timing is TDC.
If we measure the timing at 800, 1000, 1200 rpm, those measurements would fall within the timing given by the advance specifications.

upload_2021-8-18_13-37-35.png



If we took the same distributor and set the initial of TDC at 900 rpm.
Below 900 rpm, the ignition will spark some time after TDC. We'd probably find the timing at 700 rpm to be something like 5* ATDC.
If we measured timing at 1000, 1200, 1400 rpm, we'd find it about 5* less than when the initial was set at 700 rpm.
upload_2021-8-18_13-45-34.png
 
Mattax said:
They have a plug in adapter? That's nice. Got pic?

Ive always had to adapt something or use the crappy squeeze splices.
Original instructions assumed squeeze splice and leaving the electronic harness in pluce but unplugged (as a backup).
View attachment 1715783216
Not all Chrysler pickups use black and orange. Someplace I have a list of the other color codes used.
Click to expand...
I’m not using the molar ignition, I have it from dist to msd, also I should mention my car was ran with 18 bolts for a short period of time as my voltage reg died
 
Mattyb said:
I’m not using the molar ignition, I have it from dist to msd, also I should mention my car was ran with 18 bolts for a short period of time as my voltage reg died
Click to expand...
Please look again. The drawing posted is from Autotronic's instructions for the MSD 6 series.
I even marked it with a pencil to show the mopar ECU harness can be completely removed.
The important thing is the distributor piclkup wires, often orange and black, mate with the correct MSD distributor green and violet wires. If they are reversed, timing gets wacky.
 
Mattax said:
Please look again. The drawing posted is from Autotronic's instructions for the MSD 6 series.
I even marked it with a pencil to show the mopar ECU harness can be completely removed.
The important thing is the distributor piclkup wires, often orange and black, mate with the correct MSD distributor green and violet wires. If they are reversed, timing gets wacky.
Click to expand...
Thanks!! I will definitely look when I get home, never thought to look at that
 
[QUOTE="Mattyb] My issue is I just replaced the distributor with a new one from Autozone, [/QUOTE] what was wrong with the orig dist? can you swap the weights/springs/vac can from the old to the new one & are they different from each other? check that the new can doesn't have a vac leak (rare but could happen), might as well eliminate that potential as the popping is making me think of a lean misfire. Holler with any news.
 
Mattax said:
Please look again. The drawing posted is from Autotronic's instructions for the MSD 6 series.
I even marked it with a pencil to show the mopar ECU harness can be completely removed.
The important thing is the distributor piclkup wires, often orange and black, mate with the correct MSD distributor green and violet wires. If they are reversed, timing gets wacky.
Click to expand...
my dist has a black and blue wire and a black and orange wire
 
Check your reluctor gap too.......both with and without vacuum applied to the can. See if the gap gets way out specs.
 
Mattax said:
From what you describe the vac port connection seems correct. We can check that.
Click to expand...
upload_2021-8-18_17-44-41.png


Mattyb said:
my dist has a black and blue wire and a black and orange wire
Click to expand...
I don't have a direct answer on hand.
Here's what I do have.
From the same instructions.
MSD connector. Violet +, Green -
Also that on Chrysler distributors orange or White +, black -.

May have to determine the polarity of your distributor wires by looking at the connector.
The longer side of the connector is negative.
upload_2021-8-18_18-14-56.png


So whatever color is on the longer side of the connector, connect it to the MSD green wire.
and whatever color is on the shortere side of the connector, connect it to the MSD violet wire.
 
I always went by male and female instead of longer and shorter, but, maybe that's not politically correct anymore! :lol:
 
cudamark said:
I always went by male and female instead of longer and shorter, but, maybe that's not politically correct anymore! :lol:
Click to expand...
So he's positive and she's negative.
:thumbsup:

A lot more clarity that way (can I say that?)
I'm just tired and brain not fully engaging
:thankyou:
 
My bet is pick up gap is too small. With VA hooked up, the p/up coil is making contact with the reluctor. No spark is the result with mixture not combusting in that cyl. When the exh valve opens, the mixture is ignited by the exiting burning mixture from another cyl.....pop in the exh pipe.
Check the air gap, should be 0.006-0.008". Also check that the VA plate & shaft feels tight. Any movement might close up the gap.
 
Bewy said:
My bet is pick up gap is too small. With VA hooked up, the p/up coil is making contact with the reluctor. No spark is the result with mixture not combusting in that cyl. When the exh valve opens, the mixture is ignited by the exiting burning mixture from another cyl.....pop in the exh pipe.
Check the air gap, should be 0.006-0.008". Also check that the VA plate & shaft feels tight. Any movement might close up the gap.
Click to expand...
After all the greatly appreciated advice I received here, found the problem, my MSD box ! I hooked up a orange box I had and car runs perfect!
 
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