Magnum mount issue?

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71Duster

71Duster

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I put Schumacher magnum mounts in my duster when I put the engine in, I get a wicked shudder in the car with vibration starting at about 1500rpm comes and goes with rpm shifts etc... I swearched and cant find a thing rubbing anyone seen one of these moutns get stuck locked up?
 
It will show up stationary and comes and goes worse with certain rpms... when we broke the cam in at 2500rpm it made the front tires shake. Its worse of course when its moveing
 
i wouldn't run the car until you fix the problem.
sounds like a balance problem.
possible incorrect torque convertor.
 
Its the same torque that was behind my internally balanced 340 thats now behind a neautral balanced 360, The balancer is all that changed, its not high end just a professional products but has the counter weights removed for an internal balanced engine, its not noticeable at an idle untill 1500rpm and when driveing its sort of up and down with rpm and load, lets up on shift points and with certain amounts of rpm. 1500 - 2000 is the worst though
 
man that doesn't sound like a motor mount problem to me... i have their magnum mount on my dart and it is really smooth in the rpm's... try putting a stock mount on there and see if it still does it if thats what you think it is...
 
The only thing that elads me to think mount os the like is it sound slike the engine is beating on the floor boards it thuds against the car like a header rubbing but they arn't and they are TTI'S all the clerances look nice the car is pretty smooth at 2000rpm but 1500rpm is terrible and 2500rpm is getting rough.

Still working on it witht he engine builder but the numbers are supposed to be all great. He doesn't love my Professional Products balancer though

Just getting stumped and looking for all suggestions
 
Someone tell me how a stationary item with no moving parts like a mount can cause a vibration. The mounts are supposed to isolate minor vibrations from rotating assemblies or from road vibration. Somewhere in your rotating assembly it is out of balance. I have solid mounts in my Valiant and do not have any vibration because everything is in balance. Why did you not have your balancer & flex plate balanced with your engine? Better go back to your engine guy.
 
I had solid mounts when it had the 340 and sorry it had some very nice rattles etc I just thought the mount may be causeing havoc as the engine moved, locking up prematurely or somethign jsut screwed inside it. I replaced the tranny mount with no real change.

The torq is a Dynamic brand and it lived behind my internally balanced 340 without an issue.

As far as the engine goes I assume the flexplate was balanced with things as it came with the engine as far as the balancer goes I bought it on my own and was never asked too much about it. Unfortunatly the engine deal is a long distance thing from a very reputable person, needless to say I'll keep my engine jobs more local now.

I'm told the engine specs and numbers came out very very well still need to get my spec sheet to say any more.

I'm going to swap to the balancer that came off my stock forged crank 340 and see how it runs, as worn out and badly rebuilt by the previous owner as it was it was as smooth as a top.

I'm just drawing at straws here to find all the little easy things before I point to a base engine issue. Because then its a world of hell worse then now.
 
So the next questions whats everyones choice of balancer? Considering this is a street car and wont see 6 grand if its lucky.
 
did you find the problem?
a stock balancer will work fine at that rpm.
i'd check tdc and index balancer.
 
Going up tonight to swap the stocker on and see how it goes. I hope its not a base engine issue. The odd thing is it seems really bad on decel
 
Well I pulled the professional products damper off, in comparison to the stocker it is much lighter.

I had to pull the intake off so didnt bother to put the rad back in so I didnt drive it but fired it up, it SEEMS better. I can't say 100% untill I drive it it still has some vibration but how much should be normal for this new engine I can't say.

I am having lifter issues that I need to sort out with the builder so untill I get that done the intake isn't going back on.
 
71Duster said:
it SEEMS better. I can't say 100% untill I drive it it still has some vibration but how much should be normal for this new engine I can't say.
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It shouldn't vibrate at all. Period!! I had my 360 balanced at my local speed shop and he required me to take in every piece of my rotating assembly or he wouldn't do the balancing. He told me if I changed anything consider the warranty null and void. I put it together and with a pretty nasty sounding cam you can set a glass of water on the air cleaner and it won't tip over it runs so smooth. It has absolutely no virations at any rpm's. Sorry to say but something don't sound right with the balance job you got.

And I don't believe it has anything to do with the mounts. The mounts do isolate the body from engine vibrations but the engine shouldn't be vibrating as bad as your describing.
 
I gotta go with the fish guy here. Your problem is engine balance. You can go with a Fluiddampner, I did, but you'll have problems with your crank pulley. (Yet another call to March).
Short story, we put a healthy rat motor into a Chevelle with a 5 speed. Got huge vibes around two grand. Pulled it apart and found we had the wrong flywheel. (502's are externally balanced, we had reused the 396 flywheel, internal balanced). As for the vibes being worse on decel, it simple physics, objects at rest want to stay at rest, objects in motion want to stay in motion.

Revhendo
 
Well they assure me its not a balance issue. The flywheel is just the plan unweighted one that looked the same as what came off my 340.

Once I get things back together and if it refuses to loose this vibration then I'll take the thing to a local and reputable engine shop and pay them to figure it out and go back to said engine guy with their findings.

This simple engine swap is turning into a long drawn out ordeal.

Out of curiosity what degree fo damage am I causeing by running it if it is out of balance?
 
I wouldn't run it any more than it takes to test it out to see if it still has the vibration. Vibrations like this can destroy your engine VERY FAST!! It will beat the bearings right out of it and can shatter pistons and even bend rods.

I don't know enough about the balance specs of the different 340 balancers but if this 360 you have was internally balanced using heavy metal (Mallory metal is what it takes, ask the balancer if this is how he did it to verify it) you need a neutral balance vibration dampener also in addition to your neutral balance converter. The 340 steel balancer could have some degree of offset balance. Again I don't know the 340 balancers well enough to say. I do know 340 steel and cast balancers are different but that's all I know. Hopefully someone will chime in and say what the differences are. It sounds like your in the right ballpark since when you changed the balancer it got better. Just need the correct balancer to get things perfect. Maybe a neutral balance Fluidamper would take care of it if you have the bucks.
 
My 340 was a 70' date code and had a forged crank so the balancer is for an internally balanced engine, the professional products balancer flat out said what to do incase of neutral balance engine that had been rebuilt as such.

The torque I was told was ok for use behnd the engine as it had come off my 340 as well..... Starting to worry this will cost a lot because I have been driveing it trying to iron bugs out with no luck.
 
71Duster said:
My 340 was a 70' date code and had a forged crank so the balancer is for an internally balanced engine, the professional products balancer flat out said what to do incase of neutral balance engine that had been rebuilt as such.

The torque I was told was ok for use behnd the engine as it had come off my 340 as well..... Starting to worry this will cost a lot because I have been driveing it trying to iron bugs out with no luck.
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If that's the case you should have been ok with them. Sure sounds like they did something wrong with the balancing job. No matter how much they swear they didn't. Did they ever come up with the balancing sheet for you?

Just don't drive it anymore and cause more damage and maybe you'll be OK. Sad to say but it sounds like your going to have to see a local shop that deals with balancing to see what they can figure out. LOL
 
No I havent he still has to get the sheets done and sent to me, sadly a local shop for me is about 3hours away but I'll get it done... I have no luck with this car its the Christine of Dusters
 
71Duster said:
No I havent he still has to get the sheets done and sent to me, sadly a local shop for me is about 3hours away but I'll get it done... I have no luck with this car its the Christine of Dusters
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Bummer about the local being so far away. You must really be out in the sticks. These old cars are this way alot of times. My Cuda project has been alot less than desirable to say the least. I bought it from the owner of a Dodge dealership (it was one of his personal cars he owned for 15 yrs.) and he told me these great tales of wonder of how great the work was done and how awesome it was. It was tucked away in a corner where I couldn't inspect it easy so I took his word for it. Man was that a mistake!! Looked like a bunch of high school dropouts did the work on it.

Just keep your head up and it will be worth it when you get it right.
 
Well its as town of about 11,000 but not an engine shop to be had, the nearest city is 3 hours but we have the distinction of 3-4 top notch machine shops that do mostly race engines so. I was trying to save cash working a deal outta the U.S

I know how shoddy work goes, I bought my car sight unseen and had it shipped from B.C the guy had a 71' Hemi Challenger and a 70 Hemi cuda before that and talked about how great his work was..... I wouldn't let the guy work on a slant 6 let alone a Hemi
 
Well its official, through a few assumptions and human errors the engine wasn't internally balanced. I put on a my 340 balancer it got a lil better and the balancer was heavier, put the weight on for an externally balanced 360 and it smarted up A LOT.

Engine guy is going to send me a shiney new Dynamic convertor for external balance.
 
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