So an update on my '63 225 engine rebuild.

Engine (in general) is running great, very few complaints. Converted over to HEI just a week+ ago, and that made a very nice difference in pickup and overall running. Have yet to monitor fuel economy, but a carb rebuild is next to really make sure everything is fine-tuned (engine runs fine, but has been bucking and dying occasionally: I think there's dirt somewhere in the fuel system creating a clog).

The one darn thing that I still can't figure out is the stupid low-idle vibration I'm getting. I mean, it's ridiculous: it's causing the inside of the wagon to rattle beyond belief. This isn't the first time I've brought this up (see my smooth idle thread here).

Here's what I've done:

1. I've verified TDC with a new timing mark on the damper (off a few degrees from the cast-in mark), and re-set ignition timing from there to 7° BTDC.
2. Installed HEI with all the recommended components.
3. I've tightened all engine and tranny mounts. STILL, I get this obnoxious engine vibration that rattles the heck out of anything that will move.

When I was running points and I posted in my Smoooth Running thread, I managed to get the timing such that the vibration was less (although still there). Now it's back and more noticeable at low-idle, since I installed HEI. Here's the thing though:

In Neutral and above 15 mph engine runs perfect. I mean, I doubt you could ask for smoother. There's NO hiccups.

I notice the vibration is directly related to idle speed. In Neutral, there's no vibration, everything is perfect. It's Drive that's the issue. The second I punch Drive, idle drops and there's low-end vibration. Step on the gas, the vibration goes away completely. Above 15 mph, the car is as smooth as I'd want. But if I've been driving over 15, and I'm slowing down, as soon as I'm slower than 15 mph, the engine speed slows to a predictable point where the vibration comes back.

Is there something I didn't tighten? I'm telling you, I've never experienced vibration like this. This car didn't rattle like this before the rebuild, and that's taking into account all the old rubber, old engine mounts (which you'd think being worn would rattle more) old window felting & channels, loose items in the spare tire well, exhaust pipe and other worn-out absorbable materials in the car body.

Observed the tailpipe and it's visibly vibrating.

What else can I check or adjust?

Did You perchance use a 67-up oil pan?

The early A with a later pan will do what you describe.

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Yeah....Im the one who destroyed this rare, vintage automobile.....

Is your passenger's side motor mount upside down by any chance? I did that with my '66 Dart when I swapped engines and it was obnoxious.

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Joshua

Nope. Original '63 pan.

If by upside down, you mean there's a 'right-side-up' way to mount my new poly mount, I don't know what side is up. There's only one way you can put on that mount: two studs towards the engine, one stud down.

Looking at the new mount in place closely, it looks like a plain square block. I could 'flip' or rotate the mount, but I don't see any difference at all from one side to the other. It's not exactly like the factory mount, which, if I recall, has a folded metal ridge or 'lip' on one side.

This is the mount I used (mount pictured on the right).

I think the hard poly mount is the problem. Do we have anyone else here using those mounts?

The mounts can be reversed and if the rubber one is turned around it transmits an obnoxious level of vibration into the car.

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Joshua

Is there a vacuum leak or something? Sounds like its idling rough, no? Is it missing or firing on all 6?

Yes, Aggressive Ted has used them, and a number of others. He said he fixed his vibration issue, but I've tried what he's suggested and nothing has changed. Slant Six Dan has also used these mounts without a problem and I'm quite sure others have too.
How? I can see how you could rotate the mount and turn it a different way, but again, it's a block with no visible difference one way or the other, in comparison to the original passenger rubber mount that definitely had a 'right side up' way to mount it.
I guess that would happen, but since all my mounts (including the tranny mount) are poly something else is going on.

It's running very smoothly, firing on all 6 perfectly, but the vibration happens at low idle in Drive.

Okay, it's probably not the mounts then. Or not just the mounts.

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Joshua

Right. I'm willing to accept that there might be slightly more vibration than usual with the poly mounts because I understand they're harder than the rubber mounts. But this vibration feels out of line. Which is so weird because the engine is running as smooth as can be.

Sounds transmission related to me. Torque Converter, Flexplate, Mounting Bolts??? As RPM's go up it balances it self and vibration goes away. Just guessing.

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1964 Dart GT

Check the exhaust from end to end. If it's close someplace, and it's shaking around, that could very well be the issue.

CJ

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Part of Tyrde-Browne Racing

I agree with your idea.

Would a flexplate with stress cracking or loose bolts vibrate louder at low idle vs. high idle?

What about the torque converter - would a leaking or low-fluid torque converter vibrate due to imbalance at low idle more than high?

Will do. The end of the tailpipe visibly vibrates at low idle. I'll check to make sure it's not hitting