225V6 rough Idle

On mine, I don't know much history... I haven't gone nearly to the extent of testing and experimanting that MikeT has, but the symptoms that he describes are right on the money! Is there no reason to believe that a single pushrod is bent? I figured it would be worth a try...seems like a fairly inexpensive place to start. Can you tell by looking, or rolling on a flat surface, if a pushrod is bent? Would it be worth just taking them out to have a look before picking up new ones? I'm here for the thoughts of others though, so let me have it!

 

yes you can roll them on a flat surface
and if you don't know very much history on the engine, then anything is possible
but once again, when did the problem start, before or after the dist swap out
I am kind of a back to basics guy, in case you couldn't tell

 

I like the basics...I'm all about keeping things simple.

I believe the problem has been there all along, it just wasn't so obvious prior to the conversion. There was much more popping and cackling prior to the HEI and now that everything else is smoothed out and quieter, this "half-miss" has become fairly obvious.

I also have a 500 CFM Edelbrock carb that could probably use a rejetting. Any thoughts there?

 

rather than guess, here are my thoughts; back to basics
A shop with a scope can check primary and secondary ignition components and patterns; this should eliminate the ignition system, plugs, wires, etc (other than even fire dist in an odd fire engine)
do you have the ballast resistor bypassed and full 12V at HEI dist?
have you done compression and leakage tests on all cylinders? this checks the valves and rings for problems; if so, what were the results?
have you hooked up a vacuum gauge?; what is the vac at idle?
an exhaust analyzer would tell us too rich/too lean and /or possible carb problems
these are the basics and where I would start; I don't know how much of this you have already performed
guessing is good I suppose if you can afford it
I will say this again: anytime only one bank or side of the engine is affected, I lean towards the distributor
my 0.2 worth

 

hmmm... I will take a look at this list and work on it...thanks for your thoughts!

 

OK, I'm bringing it up again. I think I have it narrowed to the distributor, but I want your thoughts before I call Cape Conversions. I was right about "half a miss" I clipped my timing light on to all 6 plug wires just to be sure they were firing and cylinders 4 and 6 are skipping every few sparks, but doing so irradically. 6 does it more than 4.

By all visual indications suggested by Rich Motts, this is indeed an odd-fire distributor.
I am not 180 out.
I don't think the "primary sequence" is off as it still runs strong (maybe I'm wrong.)
I have a full 12+ V and a good ground at the coil.
I have swapped wires and plugs.
I have regapped plugs (.045)

Also, probably related in some manner, after the engine gets warmed up, it will not start. A check of the spark with the timing light indicates no spark at all! But, like I said, I have a full 12+ V and a good ground all the way to the coil.

Your thoughts please!!!

 

Although the timimg light indicates voltage through the plug wire (or at least to the spot the timing light is attached), it does not mean that the spark plug is firing properly.

Other than that, everything I read in your post indicates to me distibutor problem.
Possibilities are still high: cap, rotor, coil, module, etc. The no-start condition when warm indicates this as well.
I know this is going to sound weird: I would try another known good distibutor, preferably points, for now. If you get the same results,............ I would be at a loss for words or ideas, other than wiring, batt cables, bad grounds, ign switch, etc
hth

edit: is there a way you can hook an external ground wire from the dist body to a good ground? maybe the o-ring or gasket is keeping the dist from being grounded properly; should ground through the clamp but ?

 

Yeah, I will try a totally independent ground to be sure, but when I was checking for 12V I was using the ground that connects right to the coil to be sure it was a good one.

I will write Cape Conversions and see if they have any ideas.

 

Is your dist a tooth off? Make sure it's dead on at TDC before you go too far. 8)

 

I agree with Jim.

#1: Coil. When they get hot, they can die.

#2: Module. But when they go, they usually GO.

#3: Unseen crack or flaw in cap or rotor.

 

OK, remind me, how do we define "a tooth off." As long as the #1 cylinder is at TDC and I line up the rotor with the #1 terminal and can time it at 0 (before setting advance) I should be right on... correct?

 

That sounds about right. But remember you can be off by about 3/8" on the rotor to #1 alignment. Usually your advance is what accounts for that.

 

MikeT- did you ever get your problem solved. I just replaced the stock distributor this weekend with the DUI one. Mine acts just like you described.

I tried to original point model and it did the same thing.

 

Does the HEI really improve much in terms of engine performance? I have the stock distributor on my V6 and it runs like a champ, barely noticable shaking at idle and no popping really...well only once in a while. I see all you guys have converted to HEI but seem to be giving you guys some problems. Is it worth to upgrade to HEI?

 

was the distributor dropped or anything (maybe a contact got messed up?) when i installed hei onto my 231, my dad gave me 2 even fire dist. i didnt know the diff at the time and installed them. ran fine at idle, but died a horrid death when i gave it gas. i finally got the oddfire bought and installed and it finally got it all going. personally, i dont see how a carb can be the cause of just 1 cyl dying. if a bank or series of them (depending on intake design) was failing then i could see it being a bad side, but to only affect 1 cyl? odd for sure.
i have an oddfire 231 for sale..i am installing a buick 350 in a few months into mine and have the original t-14 behind it. all to be gone. headers, hei (bell housing stays tho.)
food for thought if someone wants it.