v6 run on question

anyone have problems with the odd fiire 225 v6 dieseling after killing the ignition (aka run on)? sometimes it will even reverse.
idle is set just a little low 600 to 630 (hei lets me get away with that)
runs smooth and great and burns cleaner with the hei now installed.
i have readjusted the idle mix. (not too lean).
timing is dead on.
cleaned and gapped plugs to .040 for HEI dist.
8 mm plug wires.
using lead subsitute additive (shouldn't help anyway?)
ran two bottles on chevron techron through two fuel tank fillups.
my next step is to find a cooler running spark plug. i have the recommended delco's in there now.
thanks for any help

 

what alternator are you running? if you are running a delco 3 wire alternator (which you likely are) you need to have a diode or a warning light (i use both) in the wire that runs from the #1 spade connector on the alternator to the ignition key. without a diode or warning light, current will travel from the #1 connector to the key, and to your coil causing engine run on even once you turn the key off.

 

BINGO!! i bet... i'll check it out. i know there is no diode. i saw that article too, but figured it didn't apply to just the set up i had. maybe because i am using a warning light.

was there a number/spec for that diode listed?

 

never mind... i found it. 1N4001. i think i might even have one on my electronics bench.

 

Using just the warning light and no diode would work with a normal points style distribitor. has the run-on only occured since you installed the upgraded ignition system?

most ignition upgrades will require the use of a diode. remember the stripe on the diode goes toward the alternator. if you don't have a diode in there, defitely put one in, they cost like 2 bucks. it will most likely solve your problem.

 

:? :?
if you truly have alt feedback, the engine won't skip a beat when the key is turned off; you wouldn't notice a thing, other than the key is off with engine still running. The diode would solve this.
It certainly wouldn't run backwards as you described.

If you have a timing issue, vac leak, rich fuel condition, these would be responsible for the dieseling/run on/running backwards issue you say you have.
The diode trick will not help with this.

 

ok that make sense. that's why when i read the earlier thread i didn't think it applied to my problem...nuts, i was hoping it would be that simple.
it's definitely dieseling.
should the hei conversion be timed @ 5*btdc as with the stock dist? mine is dead on 5*.
if so guess i'll check for vacuum leaks.
this seems to happen when it's been driven for 2 or 3 miles and warmed up.

 

for the cost and effort involved to install a diode, that would be a good place to start if simple carb/timing adjustments don't solve your problem. while a diode won't cure the engine running backwards, it will solve alternator feedback which could certainly be contributing to your problem. adding a diode cannot hurt.

did this run-on/deiseling you describe happen only once you upgraded the ignition, or was it occuring prior to that? I'm not sure if HEI would require a diode, but i know some MSD units do.

 

it happened with the old dist. as well. i was hoping that the chevron techron would clean out any carbon in the cyls. when i removed the spark plugs they were clean and the residue is normal.
i know that a hot spot can cause it.

i will probaly add the diode any way just cause it's not much of a job.

it's the reversing of the engine that's got me confused.

 

ok, well if it happened with the old distributor, it will still likely happen with the HEI conversion.

most times people bang their head after trying everything they can think of and spending tons of money when a simple 2 dollar part and 20 minutes of effort would have solved it right off the bat. thats why i mentioned it early on. but i would recommend installing it anyway. if for no reason other then to eliminate it as a possibility...

 

that's why i figured i'd just go ahead and install the diode. also if i ever find a working 6246 msd odd fire box for sale for decent price i'll already have it installed.

just found this link on ecj5 http://www.earlycj5.com/forums/showthread.php?t=3775

there's also one on the jeepster site if i can find it again. but it's all pretty much what we've been discussing here.

 

I have the same problem with my 71. Changing out the distributor to a HEI did not change things neither did changing the timing. The 71's, when sold, had a full compliment of smog controls. I don't know about early model years but the smog setup is pictured in the shop manual with the blue cover.The controls on this engine had long since disappeared before I got it. The smog controls included a throttle stop diapham that slowed the throttle closing when the thottle was released. I also wonder if there were changes to the Rochester two barrel in 71 that also may contribute to the desieling. I haven't had a chance to check the carb numbers between and early and late V6 carbs. I have a thottle stop diapham from a Ford that I'm going to install and see if that makes a difference.

 

Steve
Here is what JEEP had to say about it in my 1971 service manual. Just don't ask me what a Idle stop valve kit is:?
I do remember that when I used to have that problem, I could adjust the dash pot and that would help solve the problem.
Good luck


View attachment 9889

 

My CJ-6 has done the run-on/desiel thing since I got it. I've tried everything and would love to know what that "idle stop valve" is and where a person could get one.

 

Well I couldn't find the picture in the service manual CD, but did find a corresponding part #:

I looked around for a pic of part 4.002-1 to no avail. Hey Jim & Zoomer, can ya help?

 

Attached is a picture of the dash pot on the rochester two barrel.

 

One thing I had a problem with, was timing according to the mark on the damper. After almost wearing out a timing light with little success an old mechanic suggested timing by ear, my problem was over. Seems the old dampers slip in their old age.This was 18 months ago.

Two weeks ago when I disasembled the engine the mark was 3/8" off with the front left piston @ TDC.

 

Just to let you guys know. My '70 had run on problems when it was brand new. Used to have to pull the choke or turn the key back on and then off to kill it. Resetting the timing never worked. Dealer said it was caused by the smog pump. It still did it as of about 5 years ago (the last time I drove it). Took the smog crap off, we'll see how it runs when I get everything back together.:v6: