318 Poly Vibration

[matthon]

I took it to someone I know who owns a shop, he works on my other car himself, this one not interested in really solving the issue. Another couple places nearby want big $ to even look at it. I know a guy who knows mopars, helped a little, no time lately.
Just hitting dead ends. It's my own personal alien abduction, some people are skeptical, some think I'm downright crazy, some don't believe me at all. I need to find a fellow abductee who can tell me I'm not crazy.

Yeah, mine shakes as far as the rumble of the engine and exhaust. It also vibrates the upper horn like a tuning fork.

 

[Evan Frucht]

I took it to someone I know who owns a shop, he works on my other car himself, this one not interested in really solving the issue. Another couple places nearby want big $ to even look at it. I know a guy who knows mopars, helped a little, no time lately.
Just hitting dead ends. It's my own personal alien abduction, some people are skeptical, some think I'm downright crazy, some don't believe me at all. I need to find a fellow abductee who can tell me I'm not crazy.

Yeah, mine shakes as far as the rumble of the engine and exhaust. It also vibrates the upper horn like a tuning fork.

post a video if you can, with help here this should be easily sort-able.

 

[matthon]

No loss of power, even when it has idled crappy it drove nice.

Yesterday was a good day. It drove better than ever, plenty of pick-up, kickdown worked great. Motored along nicely, even with that 2 barrel, it goes. Power steering and power drum brakes work excellent, heater is the bomb.
Damn vibration.

I will definitely take a video tomorrow, hopefully it runs well so the vibration is clear.

 

[matthon]

I'm not sure if this will be of any help.

I used a spark plug to demonstrate where the vibration shows up.
Top of air cleaner, very front part of fenders, front cross brace, and the upper horn. The horn looks like it's going in and out of focus, but it's not, I watched it vibrate in person and on my phone at the same time.
Can't really hear it, but can easily feel it.

Not on radiator or middle/rear of fenders.

Today I felt it in the driver's seat for a short time while it was idling.

Checked entire front end, nothing loose, rattling, broken, rusted, etc. Bumper doesn't budge.

 

[miller]

Two quick off the wall things...re-check for plug wires into cap, for correct firing order. One wrong...vibration.
Other is, try idling the engine, in the dark, no lights. Your looking for any spark flashes, along any of the plug wires, or even cross firing.

Ahh, one more. Pull the distributor cap, and look inside at the plug wire contacts. There's times you'll get 'carbon tracking' between the contacts, that arc, making some cross firing.

 

[matthon]

I will re-check both.

I was not aware that the converter snout size changed either in 66 or 67, apparently, going from smaller to larger.

I have a 66 engine and a 64 trans, not to say that the trans or converter are original, but if I had to guess I would say yes.

So, the crank and converter would bolt up no problem, but the flange bolts are the only things centering it.

If it came up here earlier, I apologize, I did not understand the idea.

I'll also see what info I can locate on when the snout size changed, once again, not that my converter has never been changed, but it would be nice to know.

Hopefully I can do this asap, maybe this weekend.
This at least gives me something solid to check.

Next: unbolting the flex plate from the converter to see if I can wiggle the converter around off of center.

 

[matthon]

The information above is not correct, therefore, the above theory is flawed.

My understanding is:
1962 the crank changed from an extended 8 bolt crank, that used a cast iron trans, to the modern 6 bolt with an aluminum trans.
1962-66 318 polys came with the same crankshaft register as the 273/318/340 engines.
The exception is the 1964-7 273 crank has a smaller crank register, (and slant 6 engines).

I'm not sure unbolting the flex plate from the converter to see if it is loose is a good use of time at this point.

I need something concrete to check dammit!

To clarify, I describe the vibration as a frequency, because where it manifests itself reminds me of a tuning fork.
That was what I was trying to demonstrate in a few of the videos.

Lost again.

 

[66 Sat]

Mate I think you need to walk away from it for awhile - if the car is otherwise running ok and it's less noticeable when driving, then just try to ignore it and see how things develop in a few weeks or months. If you've got good oil pressure and nothing mechanically seems amiss then why keep going around in circles over something that some people don't even think is there? I still think it's a harmonic coming from maybe an engine mount or something, especially if it's more noticeable on body parts than the engine itself. If you can't let it go then maybe put a bigger cam in it, one that shakes the whole car at idle and move on. Or the usual response when you have a 318 poly - put a 440 in it!

 

[matthon]

Good advice.
I just don't want to make it worse.
I'm hopeful a friend can come take a look, he said he has a siriometer (?)
Sounds interesting, and I might learn something.

It's hard to just drop it though after months of work.

 

[Evan Frucht]

Ya I would say if the car seems to run well and function properly in all other aspects maybe don't worry about it for a while. I'm sure your not crazy, but in the video I can not see any vibration. You might not be able to figure out until one day in the future when/if you have the engine separated from car and transmission. Or maybe you will get lucky and talk to someone who had the same issue and solved it.

 

[Dako]

I had a plug wire that was slightly pulled back from the boot at the spark plug. Boot was completely seated on the plug but couldn't see it by looking at it. Pulled one wire at a time while it was running. Each time a wire was pulled, it ran worse...until I got to that plug...there was no change. Pushed the wire further into the boot and the roughness smoothed right out.

 

[Evan Frucht]

I had a plug wire that was slightly pulled back from the boot at the spark plug. Boot was completely seated on the plug but couldn't see it by looking at it. Pulled one wire at a time while it was running. Each time a wire was pulled, it ran worse...until I got to that plug...there was no change. Pushed the wire further into the boot and the roughness smoothed right out.

you might be onto something here, usually with spark plug issues you say yourself for a while "but I checked those!" then one day you notice something you didn't before. triple check the firing order and make sure the boots are pushed in fully, and that all spark plugs are fully screwed in. possibly worth checking again, even if you recently made sure it was correct.

 

[matthon]

I agree 100%.

I checked, rechecked, then re-clamped the ends. Then changed the plug wires to another new set because the first new set seemed sub par. Then pulled them off and put a small amount of the dielectric grease on. Then pulled the boots back, clipped the wires on the plugs, then slid the boots over.
Checked the firing order multiple times.
Also pulled the plug wires one at a time.

I've been pretty meticulous.
I obviously missed something, or made a mistake, you know, the kind where you look at it too much and can't see it staring back at you.

I long for the day when I can announce what a moron I am and everyone can say, see I told you so!

I do go back and do a basic check of suggestions like these once I've walked away for a few and start on something else.

Thank you for the input, it is greatly appreciated.

 

[Slap Stick]

In your first post you said you couldn't find a replacement trans mount.
This may be the problem.

Edit to add...

You said this comes and goes. It may be a crank dampener beginning to fail.

 

[matthon]

Time to beat this dead horse some more.

I have started it to move it around over the winter, on a trickle charger, always fires right up and idles fine, for a while.

Pulled it out today, same as above. After a little bit kick the choke off, idles fine, a little more time, starts to idle down farther, too far to stay running at a light. Not yet warmed up totally.

Took it for an hour drive on back roads. Wanted to stall at stop signs. About a half hour in, would stay running at stop, but barely, and like crap.

The below vids are after the hour.
That 4 blade fan sure makes quite the breeze.
Put it in drive then reverse.
The seatbelt buckle was chattering like crazy, which demonstrated the vibration I feel all the time.

Decided to Jurassic Park the vibration.
My dual quad 383 doesn't shake a bit.

If anyone can see/hear anything it would be appreciated.

I was thinking on getting a new carb, not sure what, or even why, just to eliminate it maybe as it's the only thing left not new I believe.

Going to try to drive it all week and see what happens.

 

[NoCar2023]

Make sure the headers or exhaust pipes are not touching the body anywhere.
Using a floor jack, lift the engine just enough to take the weight off the mounts and verify if issue is resolved, do the same at the trans.

 

[Evan Frucht]

Could you have a vaccuum leak at the at the small ID hose that goes from intake through firewall for the heater controls? Cracked vacuum line somewhere? Just a thought. If it runs fine generally but acts up at idle it could be a very minor intake leak

 

[matthon]

Headers/exhaust not touching anything.
Unhooked heater vacuum lines and plugged manifold.
Unable to locate any vacuum leaks.

Will try jack with mounts mentioned. New motor mounts, checked multiple times, trans doesn't budge on mount in/out of gear. Finally found new trans mount, yet to install.

Good suggestion on fabo followed to determine if converter is bad, to no good results:

Just tried it, wasn't stalling, large open side street, foot on brake, put in gear, foot to floor, rpms go to just above 2k and car starts to move.
Attempt #2, same result.

Immediately after, car now has severe clunking sound only when driving and turning right - not when going straight, backwards, or left.

Noticed on way to work, completed multiple large circles in parking lot, only when turning right.

Do not feel it in steering, suspension, or braking. Sounds centrally located, yet not sure. Thought maybe ball and trunion, but only on right turn?
And really don't want to blame the b&t, it took the max wedge abuse, right?

100% new brakes, 4 wheel power drum, Booster Dewey booster, adjusted perfectly, stops great. In drive or reverse, 2 barrel carb if that matters, car will pull extremely well at first flick of throttle.

This is one reason why I don't just turn the idle up to avoid stalling at stop, because if it is running better it idles too high to comfortably put into gear.

 

[matthon]

Ran like a bag of crap on the way home, 2 footing it to keep it running at lights, and/or putting it in neutral.
Thought, this has to be a vacuum leak.

Pulled in driveway, hit the brake, stayed running in gear, of course.

Checked for vacuum leaks, again, spray bottle, none.

Put jack under engine, then trans, no change.

Could a messed up carb, messed up beyond what a rebuild can fix, cause a vibration?

Willing to try a new one, any suggestions?

 

[NoCar2023]

Okay, this is a idle quality concern, I thought you had mechanical vibration or ground out issue.
How clean is the fuel tank? maybe sucking dirt into the carburetor?
Does the exhaust smell different when it starts running poorly?

I just went back and reread your posts.
October 6: new battery installed, low on gas, drove to gas station, halfway there wouldn't move, wanted to stall, felt a vibration when it started moving. Made it, needed gas to get back. Ran better by the time I got home. Checked all plugs, pulled wires apart, re-crimped a few to be sure. Checked firing order, started, ran the same, realized I forgot to plug 1 wire in, vibration remained.
Is it possible you sucked some dirt out of the bottom of the fuel tank?