Vibration issue and 318 torque converter balance

Ok so I know this kind of question has been posted before but my case is confusing me.

I have a 318 engine recently built but not by me, and a 904 transmission that I thought was bolted to another 318. But the converter is obviously externally balanced. I am getting conflicting info on if all 318 are internally balanced. If this is so it means my torque converter was off a 360, right?

I have been having a really bad vibration issue that is most noticeable at idol in park. From what I understand this means that it should be an engine issue, right? But I have gone through the basics of motor mounts, timing, and a power balance test. It still vibrates bad like it’s running on 7 or even 6 cyl. The only thing i haven't checked is idol fuel mixture. But i was seeing a clean 100rpm drop on a power balance so i didn't bother. (maybe that was dumb) The transmission has gone south so its hard for me to rely on driving symptoms. Before it did, i can say that at freeway speeds i didn't feel a vibration. If the TC was wrong shouldn't vibrations get worse?

Is this a motor or transmission vibration problem? Or is it possible i have the wrong TC and a different cause of vibration?
Help......

If you saw the weight on the converter, it could very well be for a 360, and incorrect for your 318. If it shakes but good, that could be the issue.

the TC will have some weights welded to the face of TC for a 360

a 318 does not,it may have some weights on the edge of the TC to make it a neutral balance only

a 360 Tc on a 318 will vib real bad at idle and in the upper rpm range,it will wipe the main bearings out in short order.

its hard to miss the big weights on the face of a 360 TC,they will be between 2 of the TC/flex palte bolts

older ones with a drain plug will have 2 weights on each side of the plug on a 360

later 360 TC will have 1 big weight

225/318/340 use the neutral balance TC,so any from a 904 with this engine combo is good to go

if you have a 360 TC you can knock the big weight off and run it behind a 318

the TC is defiantly not neutral. How short of order will it be before it kills the mains? Its been about 75 miles since it was put in. not liking the sound of this.

Knock the weights off,....done

FYI any (if any) thin flat weights on the rear (curved) face of the TC are not to b touched. They are 2 bring the TC hunk of metal to neutral balance at the factory then one or 2 large weights (as said) are welded on the front flat face if it is then externally ballanced & those are the ones you work w

So you all think that even in park that the wrong TQ would cause considerable vibration?

360 converter on a 318 will vibrate bad at idle. I bought a duster set up like that once. You really wouldnt notice the vibration anywhere but at idle. Easy to mistake for a bad miss.

The parts that are affecting an engines balance (crank/piston & rod assys/harmonic dampener/ TC are all spinning in park but yes it's WAY off to b shaking that much at idle

Quote:

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the TQ is defiantly not neutral. How short of order will it be before it kills the mains? Its been about 75 miles since it was put in. not liking the sound of this.

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just to be clear and same page..

TC = torque converter

TQ = thermoquad carb

get it changed or knock the weights off the face of the TC..

you may still be good with short miles..if its a good shape engine to start with, but it will hammer the mains if run as is

good luck