I was here some time back looking for any advice concerning a harmonic type engine vibration in a '55 Dodge 270 Hemi. The vibration is there when the engine is in neutral or park. The car does not have to be moving. The engine is completely rebuilt and balanced. It is being backed up by a 1995 Dodge auto overdrive with a new 318 torqe converter (no balance weights). Also there is a new design Hot Heads Hemi harmonic balancer installed. The vibration used to come in at about 1100 RPM. I tried some different weights (glue on type wheel weights) on the flywheel to see if that might help thinking that the torque converter and flywheel were the only things turning. That really didn't seem to do much good. back to square one. Some time ago I was resetting the timing and noticed that if I advanced it that the vibration seemed less and less. I am now running the engine just a few degrees up on timing. All seems well and the vibration is noticably less, (but still there). It seems that it starts to set in now at about 2000 RPM. With that overdrive trans. 2000 RPM. is about 65 - 70 MPH. Now I have put about 20,000 miles on this car since being rebuilt. I have driven it 10 - 12 hrs. straight sometime putting on 2000 miles in a weekend. Absolutely on problems. But still thinking that that vibration should not be there. Any new ideas are more than welcome
You might try moving the torgue converter mounting bolts, that is, with the bolts removed turn the converter one quarter turn to the next bolt hole and reinstall the bolts. Are the Dodge hemi's internal or external balance? I'm wondering if you might not need the weights on the converter.
The converter has no weights on it now. The 318 converter comes without weights because I believe the 318 is internally balanced. My 270 is now internally balanced. Cannot turn the converter to any different holes. They are off center so the converter only fits one way .... Appreciate the ideas ....
this is a long shot....check your fan blades...I had a bad vibration on a six cylinder ford 250....checked motor mounts and u joints.....all good....then just looking around the pulleys I noticed a fan blade broken off at the rivets...new fan, no vibration....also recheck the balancer...maybe the rubber loosened...check the crank bolt on the balancer....I also have a 1955 270 red ram hemi in my 52 ford f1 pickup with a stock balancer...maybe you have one for a 360 engine which is externally balanced...a stock balancer should be concentric all the way around...if yours has any recesses or dips along the backside, it's not the right one...
Were the balancer, flywheel and converter balanced with the crankshaft or checked with the crankshaft after it was balanced? Do the vacuum and mechanical advance work in the distributor? Is that a fluid damper or a solid balancer with the rubber ring? The fluid damper is probably better at removing harmonics but it is more expensive.
Balance, for me has meant grinding material off the rods, pistons to make them weight the same. I think your vibration is in either the harmonic balancer, unless it was on the crank when it was turned, or the converter or possibly the flex plate, I did see a cracked flex plate that produced a slight wobble, although the bolt was still firmly attached.
Stock dual point system has been converted using a low deck 318 electronic distributor. Vibration was there before the distriutor swap and after. I thought the vibration might had been coming because of the dual point distributor being worn. Seening that the 318 low deck is a drop in fit I went with the electronic hoping that was it No luck there. The harmonic balancer is a modified 340 made by Hot Heads Hemi for the 270 Hemi. It's a brand new item. Harmonic balancer was not on the crank when the engine was balanced. Checked all the mounts - replaced them all new, engine and trans mounts. Took all the belts off so nothing other that the engine was turning. The converter and flex plate are new. The new flex plate came with the adaptor kit for the overdrive trans. That vibration was in the vehicle when I was running a 904 trans. also. BUT --- that vibration changed, for the better, when I adjusted the timing. I'm thinking that's a clue. Is there anything special on setting the timing on the 270 Hemi on a rebuild? When the engine was rebuilt we lined up the timing marks, set the distributor and she fired right up. Set the timing and been driving it to this day. Liker I said, over 20,000 since rebuild and no problems but I just feel something ain't right.
I really can't come up with a reason why changing timing should change the rpm of an engine vibration.
did this backintheday as a mechanic with the car on a drive on hoist using a on the car strobe lite wheel balancer attach the the sensor to the bottom of oil pan using the magnet [mark the fly wheel with #'s around it bout 3ins apart] rev engine til it vibrats...using strobe lite see which # comes up on flywheel just like balancing a tire >try different weights til the vibration is gone
Looks like Hunter and Rema are the only ones still making the on the vehicle type of balancer. Hunter might be the only one that offers a pickup that could be used on an engine but the strobe looks like it's very large.
Who did you get your transmission adaper from? I have basically the same transmission behind a 341 Desoto hemi except mine is an 89 trany. The 94-95 tranys have lockup converters and 93 back are nonlockup. I'd say check your converter except I have he same problem and have had since I got it running. I don't like what I'm about to say but it is the only thing that makes sense. I think I should have put a dial inicator on the index hub adapter when I put everything together. I think there is a small amount of runout on that index hub. The early hemis index the flywheel/flexplates on the outside of the crank flange rather than the center hub and that is why you need the aluminum index hub. The flexplates need that smaller hub to index right. I want to pull my engine at a date still to be determined to check if the aluminum hub is off center a small amount. Another thing, is the transmission adapter centering the transmission dead center to the engine. A small amount off center would cause a vibration too. Easier to put up with the vibration than to do the work. I would never put another adapter on a hemi without checking runout. I have a 59 dodge truck 354 which is actually a poly block and to my amazement it has the later style crank flange but it does stick out about a half inch more to the rear than does a 318 sitting next to it. At least I won't have to use the aluminum hub but I will still have to use a transmission adapter.
Can't see this being the problem, but could be a long outside shot. All rubber mounts? This would probably not be the problem either unless one was broken. When you switched to the OD trans you changed the flex plate and converter or are you using the same ones you used on the 904? If you changed the the plate and conveter you have eliminated them as the cause. You are on the right track here by taking off the belt to eliminate the accessories as the cause. If you have a differant converter and flex plate than the one you had with the 904 and the vibration remained than you are down to one of three possable causes; 1. the balancer, 2. the trans adapter, or 3. the engine. To check the balancer, if you have the stock crank pulley, you could pull the 340 balancer off and swap in the stock hemi one. Or you could order a new balancer and try that. To check the adapter you check for proper transmission alignment or, if you have one, use a stick shift flywheel and bell housing. Fire the engine with just the flywheel with no trans or clutch installed. As far as the engine, I would say if you check the first two and you still have the problem, then the engine wasn't balanced properly.
you said that the damper was not on the crankshaft when the engine was balanced....this could be the answer to your vibration problem.....why wasn't it on the crankshaft when the engine was balanced ??????....the balancer is part of the rotating ***embly too.
Just some thoughts. Is the converter seating all the way into the crank hub adapter? Are you bolting the converter to the flex plate after the trans is bolted? Did you set TDC on the balancer yourself? (meaning not going by someone elses marks) FYI. Most crankshafts are balanced without the balancer and/or flex plate/flywheel. Those are balanced seperately, so if they need to be changed you dont need a complete teardown and rebalance. Something often overlooked is the rear crank flange.
The 'no-weights' issue is a red flag for me. In addition to the engine balance, the converter itself can have weights on the perimeter just to balance the converter. All of the 'newer' engines are cast crank-external balance variety and balance weight are found adjacent to the drain plug. The size of the weights will vary with the application, from 20 grams each to 125 grams each. Although the converter is part of the engine balance, the weights at the drain plug may also be part of the converter balance. Have you inspected the converter for any tell-tale signs of a spot weld that might have held a weight? .
X 2. Ive never balanced an engine without the Damper - its part of the reciprocating m*** and needs to be part of the equation. Just because it was new does not mean its completely in tune with the engine
I'm with the others on checking the alignment of the trans to the engine with a dial indicator - or just run it until it tears up the front pump in the trans and then you will know for sure - been there done that.
Forged crank 340 (and all LA 318 cast or forged crank) balancers are neutral balanced and do not need to be balanced with the ***embly. Cast crank 340 (and 360 {all cast cranks}) balancers have an offset weight on them and should be balanced as part of the ***embly.
Gentleman, hopefully this will help you to better understand balancing a " INTERNAL or NEUTRAL " balance rotating ***embly. Even in the best of race shops, including both of my own, and the one I had apprenticed with years ago, neither the harmonic balancer or the flywheel or flex plate need be with the crankshaft being balanced. This is not hoakie or a cob way of doing things either. Generally for a Chevrolet for example, internal balance we would have and use a in line 6 cylinder crankshaft { neutral balance } for balancing dampers, flywheels, flex-plates, even clutch pressure plates. The actual crankshaft for the engine being balanced is spun up on the balancer, and from there as long as the crank is neutral or internally balanced you can swap and chose other neutral balancers and flywheels and flex-plates with no negative effects to the balance what so ever. It doesn't matter if its a stock rebuild or a $80,000 race engine, internal balance is internal balance. Remember, balancing is a " black art " so to speak, for example when you calculate a bob-weight for the crank one will never know EXACTLY how much oil is on the rods and pistons while the engine is running, no one will ever know, not in our life times anyway LOL, Hope that helps, TR
Just a note on the torque converter, Chrysler hasn't had a drain plug since they came out with a lockup convertor in the early '80's. The last one I recall was on one of my old 440 cars. Cliff Ramsdell
OK ... Here's some updates. First off thanks for all the suggestions. Have done most of what has been suggested. One suggestion was the run out on the aluminum center hub adaptor. That adaptor was too deep when I first installed it. There was not enought room for any play in the torque convertor. I was looking for about 3/16 inch of play between convertor and flex plate. We took the hub and turned it down on a lathe to get the correct sizing. By doing that I think we eliminated the runnout problem. I would really like to try that strobe light idea but there isn't anybody in this area (central WI.) that's even heard of doing that. So I'm thinking that it's either a fluid damper ($400.00) and if that doesn't work go for another complete engine rebalance and rebuild, or drive it until somethin breaks and then we'll all know. Like I said I've put over 20,000 miles on it, some pretty hard miles, and to date no problems. But that doesn't mean I can start it up later today and ?????????
Do you have the original crank pulley? If you do I would pull the hot heads dampner and slap the original on it. If the vib changes than you know you are at least moving in the correct direction.
I have had a similar problem with a 354 Chrysler, I found that the rubber mounts on the exhaust were too hard causing a vibration. I have disconnected the exhausts and its seems to have disappeared. I will make new mounts this weekend and see what happens.
I just came upon this and I know it is a little old, but since you got a new dampner from HotHeads, did you have to hone it? I have always had to hone mine to fit the crank. If you didn't, are you sure its on all the way? If you did, is it too loose? Just throwing this out there.
Kind of a side note..... One thing I ran into regarding a 727 torque converter and HotHeads' flex plate....there's only one position where the 4 bolts line up. Had the flex plate and adapter in hand before mounting to the crank and wanted to make sure the holes were correct; that's when I noticed the "offset". Also, the TC hub fit snugly in the HH aluminum adapter. re: 33 Willys comment, I had to take almost .001 out of the 340 damper I purchased for a 331. There's no way that would've gone on without something breaking or seizing up. It wasn't a HotHeads unit, but may have originated in the same place.
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