Internal or External Balance?

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basement

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I have a 360ci, not sure of year. I know these are typically externally balanced motors but I think there were a few that were internal balanced. Is there a way to tell which one a guy has? Is the Harmonic balancer the difference and how can you tell?
 
The reason for my question is I just finished having the 4-speed rebuilt and put together with new clutch/bearing/flywheel and now there is a slight vibration at 2krpm and above. And everything appears tight and i was wondering if i had the wrong flywheel. The one I put in has three large holes on the engine side which is for the ext. balance 360 but the one I had removed did not have the 3 holes.
 
Excellent pics, I will definitly file these away for reference.
 
Not sure what one looks like mine (weird) but I don't think its either one of the 360's shown. Will crawl under there tonight and see though.
 
I checked last night and I have the one on the right middle row for ext balanced 360. So, with that said then I'm pretty certain I have the correct flywheel but I suppose it still might not be properely balanced though the product description said for externally balanced 360's. My next step is to pull the inspection cover off and make sure the pressure plate bolts are still tight. Any more thoughts as to what could be causing the vibration
 
Some Mopar engine balance is way off from the factory. Does the motor have the stock pistons? Some aftermarket pistons are lighter than stock so it can upset the factory balance. Did you purchase the flywheel new or used? '73 340 were external balance but they had a different balance so possibly your flywheel is a cast 340 flywheel? what diameter is the three holes on the back? better yet what is the casting number on the flywheel? this would tell you for sure.

Chuck
 
I don't know what pistons are in the block or really much of the engine history. This is the casting number on it though 4006830-360. I purchased the flywheel new from Summit and I will attempt to attach a drawing I have of it but I don't remember any identification number on it but on my old flywheel has 2264598 stamped on it if that means anything.
The three holes on the back of the new one are about 1 1/4" in diameter and do not go completely through.

360 Cast crank flywheel.jpg
 
Thought I'd show a pic of what my original flywheel looked like.

backside.jpg
 
Your old flywheel number is the neutral balance flywheel. It looks from the pic that some material was removed at the lower left. If you also look at both flywheel pics you supplied the flywheels are in the same basic position if you compare the flywheel bolts. That means that the material removed on your old flywheel would be in the same general area as a 360 flywheel. I wonder if your motor was balanced in a shop with the old flywheel? it almost looks like it was.

Did you have a vibration with the old flywheel? If you didn't why did you change?

What Summit part number did you purchase and what number was on the box?

Chuck
 
I ordered pn DCC-4529110 from summit, and I don't have the old box (oops). My old flywheel had been resurfaced already and had hundreds of stress cracks on the clutch side that couldn't be removed. There was no vibration before with the old flywheel. If I don't see anything loose after jacking the car back up in the air then maybe I'll have to take the old flywheel to the shop along with the new one and have the new wheel balanced to match the old, or am I heading down a slippery slope?
 
That was going to be my next idea and if it was my ride that's exactly what I would do. I would have the new 'wheel balanced to match the old 'wheel.


Chuck
 
Hey 340Mopar appreciate all the help with this . Just a side thought, I replaced the old style bronze pilot bushing with the new dodge style roller bearing type (which isn't as thick) and there is a small bit of open space behind it. And what if I had accidently pushed that bearing further back into the crank when I was putting the transmission back in and now the tranny input shaft isn't riding in it all the way? But I would think it'd make a helluva rackit all the time. Oh well, I've spent too much time and money on cars this year so I might have to shelve this project till later this summer.
 
A loose pilot bearing could cause a vibration if when you engaged the clutch the disc was off center a little. Here is away you could check, push the clutch in, now the disc and input aren't spinning and run to motor up to see if you still have the vibration. If you do than I would rule out the pilot bushing and the disc.

Chuck
 
Hey 340mopar, alittle update. I removed the new flywheel and took it along with the original flywheel to the machine shop and they matched the new wheel to the old. I installed it, along with some great help from my good natured wife, and bingo no more engine vibration. I've attached a pic of the new flywheel and circled the points that metal was drilled out to balance it. What i've learned from this is, unless you know the history of the engine, best to have the new flywheel balance checked before installing.

After Balance1.JPG
 
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