318 Poly Vibration

[NoCar2023]

More clues of a dirty carb.

Shaking, sounds horrible, smells worse, adjusted carb, etc, nothing works. Checked for vacuum leaks, none
I know I changed the filter twice to a clear filter, first time I saw debris I changed it immediately, I bought a bunch of filters, and it is currently full of gas. I also cleaned the gas tank out multiple times.

These are the systems of a dirty carb.
You can sometimes clear it out (temporarily) by increasing rpm then closing the choke quickly.

I think your carb has low speed idle tubes........the holes are really small in these tubes and clog easily.......

 

[matthon]

I drove this for 2 months, no issues other than a slight hesitation at 50 mph. Rebuilt carb, drove for over 2 months.

Then, that night when it wanted to stall, wouldn't move, that is when the vibration started.

Since then, the vibration is constant, at any rpm or speed.
The idling issue comes and goes, mostly stays, like today, wouldn't idle on the way home, at every light, once home immediately idled in drive with the brake on.

I don't doubt a dirty carb, I'm beginning to think there's something wrong with it beyond what a rebuild can fix.

The gas tank had a small hole in the bottom. Since it's a wagon, no new tank available, and it is otherwise in great shape, I cleaned it out and fixed it.

I got a sending unit block of plate, neoprene gasket, threaded o-ring, and the bolts with the o-rings.

Widened the hole, drilled holes, and screwed it on. Seals w/o sealants that never work and is reusable. No leaks at all.

In fact, I removed it Sunday, cleaned the tank, again, and put fresh gas in it.
I've pulled the top of the carb to check for dirt a few times, blown out the line, as well as change the filter.

I don't know if a bad/dirty carb can cause this constant vibration.
I also don't know if the vibration and idle are related or separate.

My converter test today failed, as in it appears to be good.

You guys are the only ones providing assistance, clues, tests, etc. I can't find anyone who has the time, knowledge, or both, to spend diagnosing. Most shops turn me away, quickly fold, or try to convince me there's nothing wrong, it's just an old car.

My frustration is probably showing, but it does not mean I do not appreciate your efforts and suggestions.

My kid told me yesterday that she can't wait to drive it to school, I told her it's not looking good.

She then asked if anyone can help, and I replied, fbbo. More questions followed, but I've rambled too long.

I'm going to look for a new carb that isn't crap, it's the only thing not brand new on the engine.

I'll also swap in the new tranny mount, and check the converter to flexplate bolts while I'm under there, again.

Last thing, I got a junker with a poly, I could swap the balancer and see if that cures the vibration.

If anyone read this far, thank you again!

 

[Evan Frucht]

If you have another carb that will fit try that. A carb could get clogged or damaged, even though it doesnt usually happen, but maybe you got unlucky.

Was this engine or trans ever fully rebuilt I forget what you said before?

 

[matthon]

Engine fully rebuilt, has about 5k on it, took out of a running/driving car, just sat a while.
I pulled the valve cover and pan, inspected, installed my pan and covers.
I did not rebuild trans. It shifts great, pulls great.

I have 2 other 2 barrel carbs, both need rebuilds, one is another Carter, the other a Stromberg.

 

[Evan Frucht]

Do you have an electric or mechanical choke and are you sure that is functioning and adjusted correctly?

Could it possibly be transmission issue, even though the car shifts fine, is causing it to act up at idle and drag? Just a thought since you haven't touched that.

How confident are you in the engine builder? Could something of went wrong inside?

 

[matthon]

Mechanical, adjusted a few times and working fine.
I recall wiring it open, after it's at temp, at some point, but it's been going on so long I could be mistaken.
I can try that, again.

Could very well be a trans issue. That's why I was happy to hear of a way to check the converter today. I've checked what I can, cables, adjustments, seals, fluid. I can't find a competent trans person who might know a thing or two. Most are afraid, pushbutton?

But what are the potential issues if it goes into all gears, well, lurches forward at a flick of the throttle, doesn't leak, loose fluid, or slip at all?
Converter I would imagine, but I guess not.

Ring gear is attatched to the converter, so splitting the engine/trans to run engine separately is, complicated.
And I'm not confident I could even get the car high enough, safely, to pull trans, remove converter, empty, bolt converter back to flexplate to start engine.

While I'm changing the mount, I can change the filter, again, I have another.

Engine came from another fbbo member. I don't know the engine builder. Been in contact with member, honest guy, he had no issues with it, and I didn't either for a while.

I'm thinking, if there was an engine issue, internal, rotating, it would get worse, the vibration would change over rpms and load, over time.

Seems dead on constant.

 

[Evan Frucht]

Ya if it's really consistent, and happened all of sudden one day, then there is something wrong and you just need to find it. I'm sure it can be narrowed down with help on here it just may take a while + trial and error.

You said the car has electronic ignition. Idk much about that or what needs to be done to make sure it functions properly but may be worth thinking about.

Has the issue progressively gotten worse? Of so what is the range (how bad was it right when you first noticed it VS how bad is it now and what changed)

 

[matthon]

Has remained the same since October when it initially started to vibrate.
First time I drove it any distance, it ran crappy, like it still does.

After all this time, and actions taken, vibration still the same, idle still hit or miss, mostly miss.

I need to have an in person conversation with a knowledgeable mechanic, of older cars apparently, as they diagnose the issue(s) so this can be sorted out and I can learn something.

 

[miller]

You said the car has electronic ignition.

I'm not much on electronic ignitions, but that being said...
What kind of shape is the distributor in? New, used, abused?
Say you've re-checked the plug wires...right type wires for electronic? Should be resistor...same on the plugs themselves.

Distributor cap/rotor in good shape? In the cap, look at the contact 'button' to see if it's broke. Look inside the cap for carbon tracking. Probably wrong wording here, but how is the stator gap, correct? Any signs of rust? Spark advance working right?

Just asking, considering how your describing the way it's running.

 

[matthon]

Brand new msd, new msd coil.
2nd set of wires, pulled an msd coil off a running car and tried that, inspected cap a few times.

Stator gap I believe is set by msd, but is adjustable, I'll have to check again.

Plugs and wires, resistor or not, I recall covering this, but I will check again.

I don't mind revisiting anything.

 

[NoCar2023]

See #35, this could be your idle problem, these need to removed from carb and cleaned, there tiny holes is these that must open for proper idle.
in some cases these are corroded, if that is the case the carb must be replaced.


https://www.jeepforum.com/forum/f8/do-i-drill-these-carter-bbd-565984/

 

[NoCar2023]

Google Carter BBD idle tube, tons of info out there on this issue.

 

[Evan Frucht]

I would definitely remove and dissabemble the carb again and see what you find. Does the carb body show any evidence of even very minor corrosion and surface oxidation. That's how it would get damaged most likely, only other way was if a previous rebuilder was rough with it enough to damage it.

I had a motorcycle I fixed up and It needed a new carb because the old one had sat with sludge and water in it for some years and corroded out the insides. Only time I needed a whole new carb but it does happen.

Honestly you may just want to try a new or different carb and get that out of the way. If its mostly an idle issue then your carb is an extremely likely source.

 

[KENTON]

I think the carb is what’s doing it. Also you might disconnect the PCV and the vacuum line to the power brake booster and plug them temporarily to see if you notice any changes. Make sure your gas cap is vented too.

 

[matthon]

Holy Toledo 1978GY8SE!
I googled the heck out of rebuilding a Carter when I did it, watched a bunch of videos, and I never saw that before.

I see in that link they are drilled out and the bottoms are made bigger as well. I do recall they looked like they come to a point at the bottom.
Symptoms in that link seem the same too.

This gives me hope.

I got home today, feeling defeated, I took another look, checked this checked that, etc, etc.

The passenger side motor mount was looking at me wrong, and I recalled another car that broke the same mount.
Since they were cheap, meaning ridiculously cheap and the only mounts I could find, I dug out the original one and swapped them.
Thinking the vibration had to be simple, and I had to be stupid.

No change whatsoever.

It was all warmed up from earlier, and was idling fine. Put it in reverse to just drive it for the heck of it, and it immediately stalled.

I do want to try a different carb, but I would need to rebuild one of the two others, just haven't had time to even order a kit. I looked into a new one but there are few, and look like junk.

I have disconnected the pcv, booster, and heater, with no change.

Vented gas cap, hmm. I know it has a gasket on it, and it's either tight or it will fall off. Not sure if it came with a vented cap.

I'll pull the top off that carb this weekend.

Still vibrates though.

I think there must be at least 2 issues here.

 

[matthon]

I believe I now have a resolution to both issues: idle/stalling and vibration.

Of course, I'm hesitant in stating everything has been resolved.

Thank you everyone for reading my lengthy bs and stupidity and providing suggestions and info.

Thank you @1972GY8SE for providing a specific part in the carb to check.

I realize some probably called out these issues earlier, sometimes it's really difficult to see the forest when all the trees are brand new or just rebuilt!

I like using the kiss principle, which led me to swap 1 motor mount, even though both are brand new, I checked them multiple times, removed one once too.

The old one is brick hard, when I pulled the new one it didn't fall apart, it's not ripped or destroyed, I put it in a vice and it doesn't compress, it doesn't twist, nothing.

See if you see a difference in the before and after glass of water test.

Carb: I pulled the #35 tubes out, air goes through no problem, WD40 too. Same with the hollow bolts that hold it down. Then I noticed what appeared to be tiny threads clumped on one screw at the top 'port' just below the head. And I mean tiny, stuck there, air didn't blow them off.
New cheap toothbrush and some more cleaning/air, done.

Put it back together, idled fine. Took it for a ride, no stalling. Ran on when turned off, lowered idle screw, fixed.

Smells a tad rich, so I'll check the timing and idle mix screws in a few days.

If the new rubber mounts are that crappy, and poly mounts are expensive/unavailable, I've got a number of old mounts I can use, a few actually look very good. Plus I got a nowhere to be found poly trans mount from a fbbo member.

New parts that suck and you don't know it is the worst!

Now I need to solve the clunking only during a right hand turn issue - another thread.

I will update this again once I swap all the mounts, so we will see if that stops the vibration.

What do you think, do you see a difference in the 2 videos?

 

[Evan Frucht]

I would focus on the bad idle before the vibration. And its sounds like you found some evidence of damage on the carb which you addressed and that fixed your bad idle? So I'd say your problems are pretty much solved there.

Has the front suspension been fully rebuilt? If not, that is your left turn clunk issue and also your vibration.

 

[matthon]

Idle fixed, I'll just check timing/idle mix.

Vibration, which occurs in park/neutral/drive appears to be bad mounts.

Right turn clunking sound started this week. Haven't investigated yet, but hopefully only on a right turn is telling.

 

[Evan Frucht]

Idle fixed, I'll just check timing/idle mix.

Vibration, which occurs in park/neutral/drive appears to be bad mounts.

Right turn clunking sound started this week. Haven't investigated yet, but hopefully only on a right turn is telling.

What has been replaced on front suspension ?

Right turn clunk sounds like failing ball joint.
Also look at the struts

Vibration could mean your whole front suspension is loose as well and needs new bushings etc.

With bad mounts I'd think there would be more of drive line clunking all the time rather than the vibration you describe

 

[NoCar2023]

Good news and good job saving another poly motor. those are cool engines.
Good luck finding quality motor mounts.