The Stovebolt Site Forums The Shop Area Engine Shop still misfiring

I know I have posted this before and I have read all the posts on misfires but>>>

My 53 216 misfires very iradically on all 6 cylinders. Worse on some than others. I have:

changed to a pertronics ignition and coil
no change

New cap, rotor, wires, plugs
No change

I have set the timing to many different variations
No change

The dizzy seems ok ...no play

I thought maybe it could be valve adjustment but a mechanic told me that misfire on all cylinders is almost never valves. He said there is something wrong with the ignition system.

I even checked my timing light on another vehicle to be sure it was not the culprit.

Any help is truly appreciated. This mis is robbing me of power, time and patience.

I realy don't want to replace the dizzy.

Thanks
RB53

Hy rust bucket 53, try hot wiring it and see if the missing stops, that will eliminate all the connections on the low voltage side. Just connect a jumper wire from the battery to the coil input terminal, hope that helps the diagnosis.

Have you got a buddy with an operating truck?
You could swap carbs, and then distributor.
Does it misfire under load, or only at idle?

Your mechanic is being logical.
You say it is misfiring on all 6 cylinders. That implies it has to be caused by something that all 6 cylinders have in common. That'd be the low voltage side of the distributor, the coil, and the fuel induction system.

regards,
Leon

As far as I can tell it cleans up as the rps increase.

I did have it hot wired for a long time before I installed the harness, just ot start ian and move it around. Never checked the timing that way though. It is a good thought. I will let you know what I find.

Thanks
Rich

try spraying some brake clean on the intake manifold and see if the RPM change when you spray,maybe a intake leak.

vacuum test is good..woudl an intake leak show up on a vacuum test?

Not necessarily. A leak in the intake system would allow more air into the engine, the same as opening the throttle. You would then typically adjust (close) the throttle stop to make the engine idle at 700 RPM or so, making the vacuum measure nearly normal. But the thottle might be so far from normal idle position that it could affect fuel flow throught the idle circuit in the carb. This would make it hard to adjust fuel mixture to get a smooth idle.

regards,
Leon

Rust Bucket, this may be a dumb question, but how do you know the misfire is affecting all cylinders? Have you checked the plugs or done a compression test and found all cylindeers to be identical?

Have you done a tune up, including a valve adjustment, even though the "mechanic" says misadjusted valves rarely cause the poblem you're having. It seems that in order to isolate the problem, first all of the variables (timing, valve adjustment, carb adjustments, etc) should be checked along with tightness of intake manifold and carb mounting bolts.

I have had two Crane Cams electronic ignitions fail in my '71 Dodge van that I bought new. In both cases the ignition failure caused intermittent misfiring that varied from very mild to actually shutting the engine down. Do you still have the points to try? If not, a D105 point set will work, because it fits Delco distributors from the 1920s through 1962 even though it's not listed in parts books for the old vehicles. I have that point set in my 1936 Chevy engine.

Good luck!

how about bad gas ?

Ray,
I had the smae misfire problem with the points as with the pertronix. My compression was incomplete as I had no help so I could not watch the gauge while cranking. But all the cylinders were within a few pounds of eachother and within spec. (I posted those numbers here several months ago. i don't remember exactly what they were but I believe it was between 110 and 120 for all of them.

The plugs are all different when I look at them after running. If I run hard and shut down at a high rpm they look similar to eachother. If I idle a while they all look different.

I measure the misfire by putting the timing light on each cylinder. I get irradic flashes soem cylinders are worse than others. I also get a puffing sound at the exhaust.

I am not that versed in these engines or ignition systems in general so I may be expecting too much or completely off base.

Thanks
Rich


I have not done a valve adjustment but did rebuild the carb...I have a second one I will rebuild to try out.

Joebob,

I have replaced the gas from last year...no change.

Maybe this thing just need to run for a long trip. It was idle for I don't know how long. I have just been driving it around town. I plan to take it to my summer place this year, 100 miles away. Maybe that will tell me more about the problems.

Thanks for the advice.
Rich

Here's an old trick I remember my Grandpa using on a tractor that would run but not idle well. He'd get it revved up, kill the ignition and pull the choke closed. Sometimes it would take 2-3 attempts, but it often worked. I surmise that the high vacuum created clears passages inside the carb.

Rich, these malfunctions always have a simple cause. It's finding that simple cause that makes us want to tear out our little remaining hair or take up golf. I would like to suggest that you try two things.

If turning the idle mixture screw has no effect on idle speed or quality the idle circuit may have an obstruction or blockage. Remove the idle mixture screw, spray in some carburetor cleaner, and then follow that up with a blast of air from your compressor. I have had tiny particles partially or completely plug the idle fuel circuit and the above procedure restored a good idle.

Also, it couldn't hurt to adjust the valves. That would rule out that issue. I would be especially concerned if they are too quiet. That may indicate they are not seating fully and are at risk of burning.

If the plugs are darker after idling in the driveway than after running faster on the road the float level setting may be too high or the needle and seat not adequately controlling fuel flow.

The possibilities are endless but it seems like setting everything that can be adjusted to recommended specifications is an essential starting point.

From there, swapping parts (distributor, carburetor, coil) from a properly running engine may help isolate the problem.

When you find the culprit you will say "How did I miss that?" That's what I say to myself every time.

I do have a second carb that i can rebuild and try. The one that is on there I rebuilt a few years ago but maybe I didn't do a very good job adjusting the float.

I did have the float get stuck one time and the gad poured out all openings.Of course I was not at home. But luckily I had a screwdriver and I removed the top of the carb and moved the float and all was well. I think a little piece of crud got stuck in the valve there. After that I replaced my fule filter.

Thnaks for all the advice guy I really appreiate it and this site.
Rich

If you are still getting the misfires after all that work on the ignition, then I would move on. If it is misfiring on all cylinders I think you could rule out valves(unless they are all adjusted wrong, but then the problem would happen constanty) So I would most likely think it a carb issue. Perhaps your idle adjustment is to lean? What type of Carb do you have? I would assume a rochester, my 3100 with a carter used to sputter at idle, and I cannot remember if it was to rich or to lean. try that if you have not, also maybe pull the carb and dump it out and try spraying carb cleaner in the idle port on the ID of the carb. let it dry, if worse comes to worse rebuild the carb again.

Maybe take the spare carb and the one you are using and compare the idle componenets of each(use the shop manual to identify everything) see if something is different.

You will get it. Sometimes I overlook incredibly easy fixs, until I either take a day away from it, or pull a spare and compare it.

Good luck.

yelostn

That was my thought exactly. I have a Carter carb. I tried a rochester and it was a bad one. I have a second carter now and will do what you suggest. Compare the idle components.

thanks
rich

I started having this today as well on my 49 3600 w/216 and w/1. turns out the #3 and #4 plug wire ends were arcing to the coil mount- causing stumbling. I put insulators over them(and the ends of the plugs and the problem is gone.

Do you have modern wires or period wires with no boots on the spark plug end.

I currently have modern wires with rubber boots. I am not sure how I would further insulate them.

I did at one point slide added rubber tube over the wires to see it that would help but it made no difference.

Rich

How long did the truck sit without running? Did you use a motor flush or something when you changed the oil? Are you using new generation oil? The puff out the pipe sounds like valves.
New generation oil will wipe and old cam...and since it is missing on all cylinders, wiping the lobes on the cam is where I am at since you have went through the ignition, and worked the carb.

Puffing sound, makes me think sticking valves. Don

If all of these ideas do not help, you'll need to get the manual and go through the tune up proceedure listed in the engine section. Which covers all of this but in the proper order. Also get a vacuum gauge, a great diagnostic and easy tool to use, most have instuctions on the box.

Best of luck

I am going to work on the valves and as you say Jim..from the manual and in the right order. I have checked with a vacuum gauge and that seemed fien to me. I followed the instructions that came with the gauge.


Moe,
What do you mean "wipe the old cam"? I do dnot flush this but did remove all the covers (valve, side, pan) and cleaned out all the sludge in the pan. I am using modern detergent oil.

Should I use non detergent oil?

I do get a lot of puffing. When I have some time I will do the valve adjustment and see what gives.

Thanks
Rich

PS I have no idea how long this sat idle. The PO was a spectacular liar. Everything he told me about this truck was inaccurate so I have no idea what it's history is.

I have driven is maybe 100 miles since I resurected it. Only short trips I plan to adjust the valves and take a few short trips than a long trip to my summer home 100 miles each way...wish me luck

Rich

Had a similar problem recently where the timing light was erratic on 2-3 cylinders. Thought it might be the pertronix pick up but it ended up being the distributor.

Some things to test for , since the new ignition is higher voltage use a clip lead and ground the tip of a long screwdriver and probe the coil, dist., wires, see if you get any arcing.
Look for arc marks in the dist cap and rotor.
A vacuum leak in the advance could cause the advance to be unstable. Could be in the line or dist. Disconnect the line and see if it make a difference.
A leaky intake manifold could cause a problem, retighten the bolts. Same for the carb to manifold gasket. I have sprayed wd40 to check for leaks, see if idle changes.
Check resistance of plug wires, flex them around to check for broken conductors.
This is a large list, but good trouble shooting practices.

Check the float level in the carb.

???wipe the cam?? What does that mean?

hello have you tried on a dark night open the hood with engine running look for sparks jumping from one wire to the other/ cross fireing? or your dist. could have warn out bushings/points cam lobe.leaking vacum advance diafram. wharped intake manafold. bad spark plugs,wires.sticky valve springs? intake leaks are hard to nail down. new parts do not equate to problems solved so every thing must be subject to scruninty. ps if you are running a rodchester carb, try a carter YF or a W1 it worked on my 216. weak fuel pump / bad fuel,loose wires and bad grounds can be gremlins from hell too. so start at the begining so to speak. and every thing so mentioned above. 2 heads are better than one, and I think the company on this site is some of the finest. thank's floyd

thanks Floyd... that is good advice. I have done many of thise things and will keep plugging away until I find it.


I still don't know what wipe the cam means.

Refering to Wiping the Cam means that a couple lobes on the cam shaft could be flatened out or not consentric with the other cam lobes. One way to check that out is bring each cylinder up to top dead center and check for rocker to pushrod lash or excess looseness to the rocker tip.
62Blue
Don

I was rereading the responses. Said to myself, this may be a grounding problem. Check the grounding on the dist, coil, the ground from motor to frame,battery ground , etc. Make sure you check the wires, connectors, and connector surfaces.May sound stupid, Iworked as EE for 36 years,amazing the problems of bad grounding.

Hank,
That is a good thought but all my wiring is new including all the grounds. But I will look them over again just in case.
Rich

Rich, I am by no means an expert in this regard, but I thought I'd pass it on: if indeed the puffing is suggestive of sticking valves, it might be harmless to consider an oil additive called ZDDP. This is a zinc derivative that was present in oils "of the day" when your 216 was created, and as modern engines incorporated roller rockers and such rather than solid lifters, less of this lubricant supplement was required. I recently had some machining done on my GMC 302, and the shop insisted that this additive be used, at least during the break-in period. Just a thought.

Ok, one idea that I have also recently tried. The air cleaners on my trucks are all oil baths. I would run 50 wt or 30 wt which works fine one it is hot. But when cold it is to thick and cause the truck to run rough at idle. the syptom goes away the instant I accelerate. I have began to put in about 70 percent oil(I have lots of 30w), 30 percent marvel mystery oil. the problem has gone away. Try it for grins and giggles. If you are running a paper element try the coil. I had the coil go bad on my 49 216 while dirving it to yellowstone. Caused sporadic issues, including rough idle. But my bet is the air cleaner.

I just read your post, I had some what of a similar problem on an old toyota, i had gone to a bosch platinum spark plug thinking that a newer style plug would help it run better,, definatley did not,, kept having a miss jumping from different cylinders,, changed and checked just about everything that was mentioned earlier, and it turned out to be the darn plugs went back to what was called for in the manual and the thing purred like a kitten,,

Scpousn

I have stock plugs in this and have adjusted the gap from .035 to .065 in .005 increments to see if that helped. No effect

Tonight I checekd the voltage to the coil
5.99 volts with the key on and the engine off
6.54 volts with the engine running.

I am thinking this is the dizzy. I will replace the cap and rotor again just to be sure and adjust the valves (valves wouls cause a misfire but not irregular spark)

Rich

You might check to see if your distributor shaft is bent. I had that once--just had to get another one. As a side note you might check your ground straps.

Today i did everything that everyone suggested short of replacing the dizzy.

I cleand and recehcked all my grounds. I ran a ground from the distributor housing to the grouns strap. I cleaned all the contacts i could find including the contacts in the cap and rotor.

It still misses but it is about 5 times better than before.
I took it for a ride and it starts better, runs better and purrs on the highway.

I still have to rebulid the carb and adjust the valves but today was a good day in Stovebolt history ay my house.

Also changed the oil and the rear end lube...while i was under there anyway.

RB53