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Member
Posts: 19
| I'm about ready to give up on this car, but you guys have helped me fix some other impossible things so I will try again. My parents got us this car in 1976 for us to drive to high school, but at some point later it was neglected and the engine was ruined. I had the engine rebuilt, bought new motor mounts, new tires, and repainted the car. Since then it has had a vibration in the body and steering wheel mostly at 40mph, but I didn't know where it was coming from. I have just lived with it, but my hand were tingling after driving to James Dean last year! After removing the driveshaft and running the engine, I think it is the engine or transmission causing the vibration. I supposed it could be that the new engine mounts are too hard, but they appear to be correct from my research.
I had the engine rebuilt at the local speed shop. The rebuilder said it would be too expensive to rebuild with OEM type pistons, but he had found some Ford pistons that would fit if the block had enough "meat". I assume that meant he bored it out quite a bit. Hard to believe, but that was 25 years ago!
When we first got the car in 1976, our mechanic commented that the engine was one of the smoothest he'd seen. I remember the engine idling so smoothly! It doesn't idle very smoothly now, although it doesn't seem to be misfiring. Any suggestions on what I should do next to further narrow down the problem? Maybe it is time to give up and switch to a different engine. I really wanted to get the car back to the way it was when we got it, but it is not much fun to drive with the vibration. Thanks for any suggestions! |
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Expert
Posts: 3035
  
Location: N.W. Fla. | 1st off...it's a 259, a 260 is a Ford. Need more info. Is this a new rebuild now, or 25 yrs ago? Did it run smooth after the rebuild & not now after sitting? Or not balanced back then? Besides engine mounts the tranny mount may have deteriorated and causing alignment problems. If it sat a long time did you pull the dizzy & int shaft & prelube it before start up or started it dry? If so you may have wiped one or more cam lobes. |
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Expert 5K+
Posts: 8445
 
Location: Perth Australia | If it ran smooth before, it should run smooth again
When was its last tune up?
A go on an electronic tune up machine might pinpoint something
Dont discount an out of balance wheel
But vibration is a loose term because it does not describe the frequency, is it slow like a jack hammer or is it sort of a buzz like a sander?
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Member
Posts: 19
| According to my Plymouth service manual, the engine is a 260 V8 for the P-27 model. It is the original engine that came in the car.
The vibration issue has been there for years. At the same time I had the engine rebuilt, I put new classic tires on the car. I changed the motor/transmission mounts shortly after that. I know there was no vibration in the car before doing these things. I thought the issue was with the tires for a long time, but now I can get the vibration without the vehicle moving. I don't know what a machine shop does to balance an antique engine, especially when they use different pistons in it. There is a resonance point where the whole car shakes- dependent on engine speed I think. It is there when the car is in neutral and I'm revving the engine, but it seems easier to hold that point when the transmission is in gear. By removing the driveshaft and running the car in gear, I have isolated the issue to engine/transmission/or motor mounts.
Is there a way to tell if the CAM lobes are damaged? It has good power and accelerates smoothly - up to about 35MPH and then things start vibrating. Of course, that is with a driveshaft installed! |
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Expert
Posts: 4053
Location: Connecticut | Do you have a Powerflite or a standard ? If you have the automatic, could it be an incorrect or loose tranny mount, or a lose cross brace on the frame ? Engine: I'm shaking my head that anyone would consider jury-rigging an engine with incorrect pistons. I'm thinking it could be any number of issues with the cam or seriously imbalanced crankshaft. The problem probably started small. But as you accumulated miles on the engine, became more pronounced. I would try to find a good running 260 and swap out the problem engine for that one. Needless to say, DON'T drive this car until the problem is isolated and resolved. Ron |
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Expert
Posts: 1348
Location: Valley Forge, Pa. | You sound positive it is the engine or tranny and there are a lot of things that can cause vibrations. Did you check the harmonic balance/damper? A bad harmonic balancer/damper is probably the most common causes of engine vibrations. A warped or broken crank, warped flywheel/flexplate, loose flywheel or torque converter bolts. Did you check the tranny mounts?
I used the hard polyurathane mounts in my GTO. That motor had a rough idle to start with and the hard mounts transfered the vibration through the car. It wouldn't get worse at a certain RPM. It was there at an idle and got worse as the RPMs progressed. You could visably see the motor shake the car at an idle.
I am in no way saying you are wrong and you are probably right, but sometimes when something like this happens, even though you removed the driveshaft, because you believe the vibration is in the motor you can think the vibration of a motor is still bad even though it might just be normal engine vibrations? You said you mostly noticed it while driving at certain speeds. Not trying to be a smart*** but did you go over the complete front end? The first thing I thought of as I started reading your thread was an idler arm or centerlink.
Oh well, you've come to the right forum for good help.
Good luck,
Karl.
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Elite Veteran
Posts: 889
Location: Peoples Republic of Oregon | Ford pistons...? sounds like a lazy mechanic. Just how much overbore did you end up with? Did the shop guy check compression?
Vibration. If it is there with the vehicle static then it is either engine or trans so you have to look at everything that moves and that which condition can change.
If I read your post correctly, the vibration started after the rebuild. If not correct me please.
Since the 55 did not have a harmonic balancer did the shop install one? If so, verify condition.
Internal changes in the PF? Not as likely, unless a different converter was installed and not balanced.
Was the engine assembly balanced? If not, it needs to come apart.
Internal changes in the engine? A damaged cam lobe can cause the pushrod to flutter. A broken piston skirt (or worse) will cause an imbalance.
First on my list would be to put it on a scope and check for a mis-fire at what ever rpm your vibration occurs. There are plenty of potential causes
for a mis-fire and all are relatively cheap to fix.
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Member
Posts: 19
| There is no harmonic balancer. The car has an automatic. All the transmission mounts and motor mounts were changed when the engine was rebuilt. The car has about 53000 miles on it. Since I put the engine back in myself, maybe I got something misbalanced between the engine and transmission? Is the torque converter balanced by itself, or is it balanced with the engine?
There just aren't any of those cars in this area to compare mine to. (Central Indiana) |
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Expert
Posts: 3035
Location: N.W. Fla. | Once had a problem on an O-T car about where it would shift into 3rd (A/T), turned out the plug wires were in bad shape, oddly enough. |
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Expert
Posts: 2312
Location: Arizona | This is a long shot but I have had this issue happen... Make sure the exhaust system if FULLY isolated on real exhaust hangers, not tiny little rubber donuts bolted solid to something and that NO part of the exhaust piping touches the body or frame. I had an 88 Mustang 5.0 with a wicked vibration that peaked at 2000 rpm. Turned out that the last foot of exhaust pipe that exited under the back bumper was just barely touching the underside of the bumper. Stuck a crowbar into the exhaust and bent it down about 3/8" and the vibration was gone. I have found similar problems on used cars with aftermarket/shop built exhaust systems that had crappy small hard rubber mounts and/or the piping was just barely touching other parts of the car. |
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Elite Veteran
Posts: 889
Location: Peoples Republic of Oregon | Mopar1 - 2015-10-19 10:49 AM
Once had a problem on an O-T car about where it would shift into 3rd (A/T), turned out the plug wires were in bad shape, oddly enough.
...that's where I was heading..... |
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Expert 5K+
Posts: 8445
Location: Perth Australia | Misfiring cylinder is where I was at as well with the electronic tune up
Something like this can tell a lot, otherwise we are all throwing darts, wearing a blindfold
 (tune up machine 004s.JPG)
Attachments
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 tune up machine 004s.JPG (108KB - 135 downloads)
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Member
Posts: 19
| In the intervening years, the plugs, points (and tried electronic ignition for a while) wires, and rotor cap have all been changed. Probably more than once. The carburetor was professionally rebuilt. Nothing has made any difference. The engine has never been smooth like it was before the rebuild. I'm convinced that either something happened to the engine when it was rebuilt, or I damaged/ misbuilt something when I re-installed the engine in the car. Changing the motor mounts made things worse. The old transmission mounts were soft and mushroomed over. The new ones are much harder. I did a compression check on the engine after it was rebuilt. All the cylinders had the same compression numbers, but they were lower than before. I think I have done all the things I can think of other than swap the engine out. The engine does not consume excessive oil or anything like that. I have never driven it more than 40 miles at a time due to this and other issues. I got the other issues fixed finally and would really like to start driving the car longer distances. Engine work is out of my league, so I will have to find a mechanic somewhere to look at it. I've not had good luck with mechanics on this car in the past.
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Elite Veteran
Posts: 889
Location: Peoples Republic of Oregon | If you have the finances to find a cure then I'd suggest finding someone who is intimately familiar with the Poly and Hemi engines and drop in their lap
for disassembly and inspection with the idea of a proper rebuild. Depending on what the idiot did to the bore diameter you may or may not have a usable
block w/o 8 sleeves (which I don't recommend due to cost). Yes, it will get a bit expensive so you have to decide what your level of vibration intolerance is.
You could also shop around for a 270 short block (much easier to find than the 260) and reuse the rest of your parts. |
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Expert
Posts: 3035
Location: N.W. Fla. | Perhaps have it disassembled & see if the rotating mass was balanced or not, valve clearance with the Ford pistons & see if the C/R can be determined. Mike the bores to see how much overbore there is. |
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Expert 5K+
Posts: 8445
Location: Perth Australia | My thoughts now (as the engine always vibrated after he rebuild) runs towards out of balance pistons (not even weights)
Without seeing it all, its all guesswork, but assuming the valve reliefs had to be cut into the ford pistons, if they just hacked them out, then the pistons could all weigh different amounts, but (as said earlier), the rotating mass is the most likely culprit, whatever it is, it will be in the engine
Replacing the engine might be the cheapest coarse of action for you, but I think, cheap will be a relative term
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Member
Posts: 19
| I think my best bet is to look for another engine to try. sigh
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Expert 5K+
Posts: 8445
Location: Perth Australia | Sorry to sound like a bit of a vulture, but I, for one, would like to see a post mortem on that engine
Sometime unusual things need to be done to get a vintage engine going and it would be interesting to see what the engine builder has done
If the engine you have is original to the car, I wouldnt throw it away, but keep it aside for the next custodian of the car
The other thing is that as its coming up to winter in your 1/2 of the world, maybe (if its possible), you can get it fixed?
Otherwise, if you can find a good running s/h engine, just re seal it and give it a paint and save the other one for later
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Member
Posts: 19
| It is the original engine. There is still a chance the vibration is not from a problem in the engine.
I was suspicious of putting different pistons in and it wasn't an issue of money for me at the time. I just thought they knew what they were doing. Since I don't know anything about rebuilding engines, I'm at the mercy of the shop.
It can't hurt to have a spare engine. I can still drive around town with what I've got. I just don't want to take it on the highway anymore. |
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Expert 5K+
Posts: 8445
Location: Perth Australia | I know you have been driving it a while, but I would try to limit that until you sort the vibration
Vibrations can cause damage to lots of stuff other than the engine and your hands
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Elite Veteran
Posts: 889
Location: Peoples Republic of Oregon | Like Mick says, a post-mortem is in order to determine exactly what is wrong. There is 'some' chance that it can be corrected, even if it lies between 'slim and none'.
Give us an idea of where you are located and perhaps we can guide you to a better shop. |
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Member
Posts: 19
| I'm located in central Indiana. |
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Expert
Posts: 4053
Location: Connecticut | Since you don't work on engines, I would recommend that you put the money into finding and possibly rebuilding a correct engine. Do you really want to spend 1000+ dollars just to find out that your crank is toast ? Unless you can find a good engine locally, transportation costs of the new engine will be significant. Better to spend your $$$ there. Ron |
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Elite Veteran
Posts: 889
Location: Peoples Republic of Oregon | These guys have been found to be a good source for EarlyHemi engine work:
*B & B Sales & Service 7501 N Hall Rd.,
Monrovia, IN 46157 (317-996-6375) Mel or John
*Rhyne Competition Engines 5733 West 25th Ave. Gary, In 46406
(219-845-1218) http://www.rhynecompetitionengines.com/
Additional info here: http://www.jalopyjournal.com/forum/threads/hemi-tech-index.118764/
As to freight costs, we have found that truck LTL, for a pallet, will run about $500 between most locations in the US. Shop around.
As to 'correct' engines, NO ONE will be able to tell if the P27 stamped 270 is a 270 compared to the P27 stamped 260...just sayin'......
Edited by wayfarer 2015-10-24 1:34 PM
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Member
Posts: 19
| Hey, thanks to all for the advice, and the link to the place in Gary. I actually have a cargo van that can haul the engine in. I'm going to have a mechanic look at it before I pull the engine, though. I ran the engine up to 30 mph in low and didn't get the same vibration anywhere in the engine RPM range. |
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1955 Ply 260V8 Vibration
