318 Runs like crap

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moparspares

moparspares

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Hi

My duster is running like crap. Idles really rough and shakes up to around 3500RPM then seems to go ok. I have changed plugs and leads and put the timing light on and all seems good. By the way I have a hunch that the alternator is not charging the battery. Could this interfere with electronic ignition. Could this be my prob
 
Anytime you dont have a good 12 volts strange things start to happen, it could be your problem, sometimes gages and other things will act funny too.
 
Yes electronics need a full 12 volts.
If you have enough power to start it you should have enough to run it.
Not enough info provided.
All stock ?
2 brl. ?
4 brl. ?
Base timing set at what ?
Check gap at pick up to be .008 ?
 
bad coil maybe - Ive seen motors do exactly what you are describing with a bad oil leaking coil.
 
Actually, vehicles don't run on "a full 12 volts." They run on 14!!!!

I would see what the running (fast idle) battery voltage is. With the engine warmed up, and the battery "normalized" assuming it's charging, running voltage should be 13.8--14.2, certainly not below 13.5, nor above 14.5

One problem with "you guys down there" is I'm never sure how close the out - of - the - states cars are electrically to ours. At least one guy on here showed up with a Bosch? Motorola? alternator that he claims was "factory."
 
Car is bog stock. It has a brand new carter BBD. Timing set at 8 degrees. The other thing I thought it might be is the distributor. I have another here I might put put in just to see if it makes a difference.
 
Misfiring? Need more info than runs like crap & shakes.
Have you tried a power balance test to see what cylinder(s) might be weak? Disconnect the plug wires 1 at a time, hook up a tach(if not equipped) & observe the RPMs Check the manifold vacuum & tell us what the gauge reads. Is it a steady reading or does the needle fluctuate rapidly? Valves sticking or mis adjusted? Vacuum leaks? Could it also be a mechanical imbalance problem? Loose or incorrectly balanced converter or wrong balancer? The more info we get the better the advice we can gladly give you.
I don't want to sound smug or smart, just asking for more to go on so we can help a fellow brother out.
 
Ok fixed the charging problem. Amp guage was flickering in the negatives. Checked the wires and the blue wire to alternator was just sitting on terminal and not pushed down all the way. Pushed it on and now needle is in positive on amp guage. The car still has a horrid shake on idle though. Im thinking it is an electrical gremlin. I am going to swap out the distributor to one from the magnum engine im building and also try another coil and report back.
 
Sounds fun, It seems like it may a distributer issue, possible mechanical or vacuum advance issue.

Sound like an problem I had, I doubt it's the same unless the distributer was the original or at least a high mile one..

My 318 always ran great until I did some basic upgrades, headers, intake, carb, etc.

The point being, during this time the distributer was pulled out for more room to work and it had no visible excessive ware, so it was reused and put back in. All seemed good on start-up, fast idle a little ruff but expected, timing was dialed back (with the vacuum advance unhooked and capped) and carb adjusted to maintain idle and once up to temp the timing was checked and was in a working range about 7 degrees. So I began to advance the timing and adjust the curb idle screw to maintain idle and this was not a easy as I expected, extremely small distributer adjustment seem to have a larger effect then it should have. And as I got closer to where I wanted test runs began to show power loss or vibrations.

This all turned out to be a combination of a weak mechanical advance inside the distributer, and a slight bend in the distributer shaft (not noticeable by eye or finger feel). This was causing excessive timing under load and a slightly difficult setup, I have come to believe that the distributer could have been like that for a long time, but never had a chance to show itself because it was locked into position until I took it out for the work. And after a new distributer, all was good again.

I'm not sure if this will help but I have come to find, only test and replace one part at a time when diagnosing a specific problem, if you change 2 or more you may never know for sure which part was bad and which one was just looking old.

good luck, let us know what the outcome is
 
Also just quick question, after that post........

Why is my member profile picture not showing when I post?

I don't know?, I just wish people could see my old Duster.

sorry just venting
 
moparspares said:
. The car still has a horrid shake on idle though. Im thinking it is an electrical gremlin. I am going to swap out the distributor to one from the magnum engine im building and also try another coil and report back.
Click to expand...


Rough idle....

If the car will stay running, try to disconnect each spark plug, one at a time and see if it stays the same or gets worse. If it stays the same, you may not be firing on that particular cylinder and may have a bad wire or plug. Even if they are new, doesn't mean that they are good. Check the resistance on that wire and see if it is higher than others of similiar length.

Also get a spare spark plug, and disconnect a distributor wire and connect it to the spark plug and then hold the bottom electrode of the spark plug to a good ground (intake works well) and then crank the engine over to see if it sparks. You may want to try this with each wire.


Have you also done a compression check to make sure that you have good compression and no bad cylinders? If you do, check them both dry and wet (with a few squirts of oil) and see if it makes a difference.

Have you pulled the spark plugs to see what condition that they are in?
 
Ok car still running Real Bad. This is what I have done so far

New Plugs
New Leads
New Rotor Button
New Dist Cap
It has a new Carburetor (Reman carter BBD)
Checked voltage at pos coil while cranking and is showing 7.5V (Should this be 12 volt?) or is 7.5 enough for it not to run bad.
Replaced both bad connections at coil
Has good Spark.

This is what I know

When cranking makes a horrible noise sometimes like starter is missing cogs on the flywheel. (not sure its that though)

When I do the timing and aim the light at balancer the timing mark is really erractic and touchy and it is hard to set it correctly. I only have to touch the distributor and the mark moves signicantly.

The car runs really bad surging and shaking but when I get to approx >3500 RPM it seems to smooth out.

Could this be a distributor problem or I'm thinking even a timing chain or EGR Valve. Has anyone had these symptoms. I am running out of things to try and dont want to keep throwing money at things that dont need replacing.
 
moparspares said:
Ok car still running Real Bad.........................

Checked voltage at pos coil while cranking and is showing 7.5V (Should this be 12 volt?) or is 7.5 enough for it not to run bad.
.
Click to expand...

How did you check this? If you checked while jumpering the starter relay, it doesn't mean much. Check this way:

Clip your meter to coil pos and ground. Crank engine USING THE KEY. Post reading

Clip meter to starter relay battery stud and ground, crank using the key, post reading

Clip meter to starter relay battery stud, other lead to blue field wire on alternator. Turn key to run with engine not running. You are expecting a VERY low reading. Hopefully less than .4V (4 tenths of one volt). The LESS the reading is, the better. Post results






moparspares said:
When cranking makes a horrible noise sometimes like starter is missing cogs on the flywheel. (not sure its that though).
Click to expand...

This could be timing "kicking back" or a mechanical issue. Simple. Pull the coil high tension wire out and ground it, crank it over. If the noise stops, its a timing issue. If not, a flywheel/ starter/ loose flexplate, etc.

moparspares said:
When I do the timing and aim the light at balancer the timing mark is really erractic and touchy and it is hard to set it correctly. I only have to touch the distributor and the mark moves signicantly.

The car runs really bad surging and shaking but when I get to approx >3500 RPM it seems to smooth out.

Could this be a distributor problem o.
Click to expand...

This indeed sounds like some sort of distributor / related problem. I'd pull the distributor and inspect for shaft play/ wobble. Take a screwdriver and wiggle the drive gear down in the engine. These have a bushing in the engine block and they can wear.

You have a shop manual? You can download a factory manual, free, here:

http://www.forabodiesonly.com/mopar/showthread.php?p=1970088617
 
Sounds to me like you have a dead hole ie no compression. Has that been checked?
 
CudaJunction said:
Sounds to me like you have a dead hole ie no compression. Has that been checked?
Click to expand...

Done Compression test

Engine COLD figures
1 90
2 80
3 85
4 85
5 95
6 90
7 95
8 85

So no there is no dead cylinder. These are pretty low I know but remember this is a cold figure and they are all about even so there is no dead cylinder. It just indicates a worn motor. I dont believe this is the cause of my problem.
 
moparspares said:
Ok car still running Real Bad. This is what I have done so far

New Plugs
New Leads
New Rotor Button
New Dist Cap
It has a new Carburetor (Reman carter BBD)
Checked voltage at pos coil while cranking and is showing 7.5V (Should this be 12 volt?) or is 7.5 enough for it not to run bad.
Replaced both bad connections at coil
Has good Spark.

This is what I know

When cranking makes a horrible noise sometimes like starter is missing cogs on the flywheel. (not sure its that though)

When I do the timing and aim the light at balancer the timing mark is really erractic and touchy and it is hard to set it correctly. I only have to touch the distributor and the mark moves signicantly.

The car runs really bad surging and shaking but when I get to approx >3500 RPM it seems to smooth out.

Could this be a distributor problem or I'm thinking even a timing chain or EGR Valve. Has anyone had these symptoms. I am running out of things to try and dont want to keep throwing money at things that dont need replacing.
Click to expand...

Don't spent money until you know what you need....
I have a 73' 318 duster that is basically stock and I had similar issues when I tried to freshen it up:banghead:

My questions starts with....
1- is the car a automatic or manual?
(they use different carbs, as well as react different under load)
2- can the car be tuned to start and idle o.k.?,
(even though there is a noise during cranking)
3- Is there any possible play in the chain?
if the car is off and cold, rotate the engine to TDC and remove the driver side valve cover and then rotate the crank slightly back and forth to be sure there is movement in the valves. (there should be little to no slop between the crank rotation and valve movement.

These are "starting point" questions,
the rough running at this point seems to be a tuning issue simply because these are basic systems and a lot of parts have been replaced. It could be a simple little adjustment, tuning comes into play at low rpm (ie. coming off idle to about 3000rpm),

and as for the rough sound during starting, just pull out the starter and rotate the crank bit by bit and visually look in at the flywheel to check for damage to the teeth as well as use a basic little depth gauge and check for warps as you rotate. Also you can test the starter working order as this point, or take it to a local alternator/starter shop for a quick test.

Let us know,
good luck
 
MY 74 dart 318 has the same symtoms you have, smooth at idle, in park
rough on exceleration, shakes, then smooths out.. I've done everything
I know of. But then I did a timing check with an adjustalbe timing light, seems
the car with the vacuum connected is pulling like 44 deg adv.
So there is an ajustment in the vacuum canister, to increase the pull needed.
or lesson it. I contacted "Richport" who makes my Dist and they confirmened this.
Would be nice to have it in print when you get the Dist..
So I'll try adding some resistance to the vacuum tomorrow and see what
happens. Alan said it should only pull to around 25deg BTDC at idle with
vacuum attached...
Which I was thinking, and 40+ is max..
Best
 
I would be checking for a bad timing chain. with the low compression all the way around./should be around 150psi
 
when I bought my '68 340 at the wrecking yard (years ago) they said the guy traded it in for a 318 because it vibrated and wouldn't run smooth. Got it for $100. I found it had a broken forged crank. just sayin'. start with the basics. I've see many CHEBBYS with sucked intake gaskets, could be something simple.
 
Did it run good before the new carb?? Sometimes reman carbs don't do what they are suppose to do. If it is an older 318, many times just a simple valve job fixes the compression and if the bottom end is holding good oil pressure, your set for awhile. The older 318's don't have hardened seats. I've done a few of these, and a simple head swap or valve job makes a seemingly "tired" engine all fresh! Gas mileage and performance shoots through the roof! Timing chain is a good idea too, even if that doesn't fix the rough running, it sure beats walking. I bet getting the compression up to 120 psi per cyl and a new timing chain would do wonders for that motor. A high mileage timing chain with tons of slack will cause timing to jump all over.
 
have you had the intake manifold off? Ive had some 318s that have the exhaust cross over completely clogged and they run like crap.
 
Did this thing run okay, before you did anything,, or did the issue develop after you messed with it ???
 
Burnt, warp, or sticking exhaust Valve?

I had a 318 slowly work into a shake and found that an exhaust valve was burnt. It seem to run ok above 2500 rpms, then at an idle would shake like it was about to fall apart... I could feel the power loss, and it would have like a miss to it when driving.
 
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