318 +.030 Dieseling

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swies

swies

Wish I had more time.
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:banghead:
After reading much about timing, (thanks to all that helped my cause), I advanced my initial to *10 BTDC. That puts me all in at *35.
Now the issue is it want's to diesel when it gets warmed up.
I am missing something, just not sure what..
:eek:ops:
 
Advancing the timing should have helped after-run, not worsened. What is idle speed and how did you set that up, and adjust mixture? How hot does the engine run?

And to be clear we ARE? talking about run-on after shutting off the key?
 
Thanks for the quick reply and sorry for the lack of info.
Idle is 800-850 in gear and just over 1000 at idle.
Idle mix and speed were done with vac gauge method. Ended up 1 1/8 turns out at max vac. Cam gives it a lope but it idles fairly smooth considering.
Engine runs at 185* when fully warmed.
And yes, I am talking about Run-on after the key is turned off.
 
10* initial is not enough for a 318 with a xe268h, closer to 18 is where it will run better/best. Keep advancing timing until you find the point where it kicks back on the starter. Then back it off a bit.

You'll have to fix/limit the mechanical advance in the distributor.

Engine should idle easily at 800-850 in p/n and a slight drop when in gear.
 
Yeah those blades are just too far open. I have a cam at least one or two sizes bigger than that, and it idles down to 600 pretty easy.(4speed tho).No, 600 is not my idle speed. Just saying.
Almost sounds like your TC is a little tight.
Make sure the Vacuum advance isnt interfering.
 
AJ/FormS said:
Yeah those blades are just too far open. I have a cam at least one or two sizes bigger than that, and it idles down to 600 pretty easy.(4speed tho). Almost sounds like your TC is a little tight.
Make sure the Vacuum advance isnt interfering.
Click to expand...

Not sure what you mean by those blades are just too far open.
Sorry for the ignorance.
Still trying to learn something new everyday.
47 years and still working on it....
 
crackedback said:
10* initial is not enough for a 318 with a xe268h, closer to 18 is where it will run better/best. Keep advancing timing until you find the point where it kicks back on the starter. Then back it off a bit.

You'll have to fix/limit the mechanical advance in the distributor.

Engine should idle easily at 800-850 in p/n and a slight drop when in gear.
Click to expand...

I have the Accel MOPAR replacement distributor. PN 59301.
Didn't come with instructions as Accel said it is a "direct Plug and Play so no instructions are required".

How do I limit the Mechanical / vac advance?
 
What would ignition timing have to do with dieseling. Isn't your ignition off when this happens ?

Or are you talking about pinging or detonation. In any case perhaps you have a build up of carbon in the pistons that needs to be taken care of?
 
Well, when the idle timing is not advanced far enough with a healthy cam, the blades, thats butterflies, or throttle blades, have to be opened quite far to keep the engine running. Then at engine shut-down the engine is able to draw in air past them, with accompanying fuel. Then if there is sufficient heat in the chamber, the mixture will attempt to burn, and you get run-on,also called dieseling.
The cure is to give the engine the timing it so desperately craves. Then the blade-opening can be reduced. The result is a smother idling engine with a better tip-in response, increased drive-away torque,and no more dieseling.
When this is done, most times the maximum power timing is also increased perhaps to the point of detonating under full-load/full-rpm.Detonation has to be avoided, or the engine will begin to self-destruct.
These modifications have to be performed to just about every mechanical distributor by just about every hotrodder.
After the idle-timing and power timing are worked out, the dizzy is ready for fine-tuning of the rate-of-advance.
And finally the vacuum advance is tuned for part throttle torque and cruise economy.

There are numerous threads on modding the dizzy. Give the search button a chance.Leave the V-can disconnected, until you get the mechanical stuff figured out.
 
AJ/FormS said:
Well, when the idle timing is not advanced far enough with a healthy cam, the blades, thats butterflies, or throttle blades, have to be opened quite far to keep the engine running. Then at engine shut-down the engine is able to draw in air past them, with accompanying fuel. Then if there is sufficient heat in the chamber, the mixture will attempt to burn, and you get run-on,also called dieseling.
The cure is to give the engine the timing it so desperately craves. Then the blade-opening can be reduced. The result is a smother idling engine with a better tip-in response, and no more dieseling.
When this is done, most times the maximum power timing is also increased perhaps to the point of detonating under vfull-load/fullRPM.This has to be avoided, or the engine will begin to self-destruct
Click to expand...

So I need more initial timing.
I am at 10* now, what should I be at?

This is what I think I am understanding ?!?
If I get to that (what ever it is) my All In timing will likely be too high so I need to limit the distributor advance. How do I do that on my Accel 59301? Like I said above, there are no instructions since it is a "Direct Plug and Play"
Thanks for the help!
 
Let me refer you back to post#4

Perhaps you dont need to do anything. What is your "all-in-timing" now? With oem or oem-type iron 318 heads, the power-timing requirement usually falls between 34 and 36 degrees.
Doing the math 36 less 16 = 20*, and 34 less 18 = 16*. So you are hoping for an average of those two; (20 +16)/2=18* of centrifugal in the dizzy.Thats 18 +/- 2 degrees
What I would do is this; Start her up with the timing lite hooked up. Rev it up to as high as necessary such that the dizzy stops advancing. Record that rpm and that timing. Let the engine idle for a couple of minutes, to cool off.While its doing that, compare your maximum number to 36*. That is the amount that the power timing would have to be changed to bring it to 36*. It also the amount that the idle-timing will need to be changed.So just reset the idle-timing that amount. Then retest the maxtiming at the previously obtained maxtiming RPM . All good? ok then lets look at the numbers.
What is the idle-timing adjusted to ,for the 36*of power timing? You are looking for a 18 +/- 2 degree spread. If you dont have it, now its time to mod the dizzy.
 
I am not sure of All In amount. I have just read and made a timing tape that I will install tonight and test / measure all in.
Back to the original post.
If my current 10* is too retarded, would that cause the run-on?
You have answered many questions so far and "Thanks" for that.
I appreciate the information.
 
swies said:
If my current 10* is too retarded, would that cause the run-on?
Click to expand...

yes yes YES!!!

You now get to learn about the insides of that distributor.

Set the idle timing as mentioned, probably going to be in the 16-18 range, maybe slightly more. You'll be able to turn the idle speed screw out as you increase initial timing. The total could be 34-36 which is a generally safe range for a SB mopar with open chamber heads.

Adjust the mechanical advance to get your 16-18* of mechanical advance and you are likely good to go.
 
swies said:
So I need more initial timing.
I am at 10* now, what should I be at?

This is what I think I am understanding ?!?
If I get to that (what ever it is) my All In timing will likely be too high so I need to limit the distributor advance. How do I do that on my Accel 59301? Like I said above, there are no instructions since it is a "Direct Plug and Play"
Thanks for the help!
Click to expand...

Are you not reading your own thread? Post #4 clearly gives a recommendation for initial timing.
 
Another thing that may be contributing is if the carb is getting hot, Edelbrock carbs are prone to boiling the fuel, which can help contribute to the dieseling.
 
Thanks RRR, I am reading the thread.
IN the mean time, I am trying to learn how to set up the whole thing AND figure out why my motor is dieseling.
 
AJ/FormS said:
Let me refer you back to post#4

Perhaps you dont need to do anything. What is your "all-in-timing" now? With oem or oem-type iron 318 heads, power-timing usually falls between 32 and 36 degrees.
Doing the math 36 less 16 = 20*, and 32 less 18 = 14*. So you are hoping for an average of those two; (20 +14)/2=17* of centrifugal in the dizzy.Thats 17 +/- 2or3 degrees
What I would do is this; Start her up with the timing lite hooked up. Rev it up to as high as necessary such that the dizzy stops advancing. Record that rpm and that timing. Let the engine idle for a couple of minutes, to cool off.While its doing that, compare your maximum number to 36*. That is the amount that the power timing would have to be changed to bring it to 36*. It also the amount that the idle-timing will need to be changed.So just reset the idle-timing that amount. Then retest the maxtiming at the previously obtained maxtiming RPM . All good? ok then lets look at the numbers.
What is the idle-timing adjusted to ,for the 36*of power timing? You are looking for a 17 +/- 2or3 degree spread. If you dont have it, now its time to mod the dizzy.
Click to expand...

I just got off the phone with Accel. My distributor has 22* of mechanical advance from the OEM.
If I am at 18* initial as stated above and max is at 36* ish, does that mean that I want to limit the vac advance to 18*? or let the vac advance do all that it can and adjust the mechanical to limit at 36*?
 
swies said:
I just got off the phone with Accel. My distributor has 22* of mechanical advance from the OEM.
If I am at 18* initial as stated above and max is at 36* ish, does that mean that I want to limit the vac advance to 18*? or let the vac advance do all that it can and adjust the mechanical to limit at 36*?
Click to expand...

Vacuum goes beyond your initial and mechanical advance.

So it's Initial + Mechanical = Total then add Vacuum.
 
No
If theres 22 in the dizzy; you set the max to 36, and idle will fall to 36-22=14. Thats a good start.
Install it. Set it. Prove the 22*.Then take out whatever you need ,to limit the centrifugal to 18=+/- 2
Leave the vacuum off. Plug the line from the carb. Forget about it, until the mechanical is sorted out..

Go do it. Now. No more talking..................................lol
 
AJ/FormS said:
No
If theres 22 in the dizzy; you set the max to 36, and idle will fall to 36-22=14. Thats a good start.
Install it. Set it. Prove the 22*.Then take out whatever you need ,to limit the centrifugal to 18=+/- 2
Leave the vacuum off. Plug the line from the carb. Forget about it, until the mechanical is sorted out..

Go do it. Now. No more talking..................................lol
Click to expand...

Thanks.
I will do it tonight!!
 
So I got a vac gauge and timing tape. This is what I found.
Idle 10 btdc
21* at 1650
23* all in at 2850
These with vac advonce plugged.
Found ported vac had 5".
Went thru and set idle with vac gauge to 850 smooth, 600 in gear and vac dissapeared from ported.
Set initial timing to 15* btdc.
26* @ 1700
28* @ 2850 all in.
That would be all mechanical advance.
Then went to vac and immediately found bad diaphram in dizzy.
Crap.
Will have to get one ordered.
Question is can I run it Friday without the vac if it doesn't get here in time?
And if so, what will I need to change if anything?
 
I'm out.... Last volley

Last time, set the timing at idle to 18 degrees BTDC. See how it runs. Reset idle speed and readjust the mixture screws.. I bet your big RPM drop into gear disappears. If not you have a likely vacuum leak somewhere. Those carbs are notorious for having linkage interference with intakes, especially on the pass side. Look for fuel dripping in from the boosters as well, another bad issue from too high fuel pressure.

Keep revving it up until it stops advancing to verify the mechanical advance in your distributor. Could be 4K+ for RPM. If it's got 22* mechanical, you are WAY short from my math. LOL

DO NOT connect the vacuum canister to ANYTHING when doing this. IGNORE THAT POS CAN FOR NOW!
 
Will do.
Sorry but it was late and I was low on energy.
I get up at 4:00 am for work and I was running out of steam.
The timing tape kicked my *** trying to get it put on between the water pump and the power steering pump. My Ham Hock hands didn't want to fit very well.
I will set to 18* and go forward with the idle speed / mixture adjust.
I agree the math does not add up and that threw me for a loop. Had to check / re-check / re- re-check to make sure I was seeing what I was seeing.
Thanks for the help.
 
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