Balance issue… help!

[Prestidigitator]

First and most importantly your talking to a novice here.

Bought a 347 stroker motor from and unnamed big time crate motor company far, far away from where I live.

I sent them the pulleys and brackets that I had previously purchased from another manufacture.

They sent me a video with it being dynoed, with my pulleys and brackets on there and it is unmistakably my motor. In the dyno video it runs smooth as glass.

It’s a 28oz externally balanced motor.

I get the motor but unfortunately due to circumstances in my life was unable to get it installed in a timely fashion.

By the time I get the motor in and running more then a year has passed by and the warranty is now expired.

The motor fires up and sounds great, one problem though it has a pretty bad vibration.

So once I get the mufflers on it and start driving it I can’t seem to figure out this bad vibration.

I take it to a few guys I know and they all come to the same conclusion that it’s a balance issue.

Right now it is at a shop of a fairly supposed well respected motor guy.

He tells me it’s the balancer in the pictures and video and that the flex plate is indeed a 28oz.

Yet, the motor still runs rough.

He tells me there is about 6-9 different combinations he is going to try to get the motor to balance without taking the transmission apart and taking off the flex plate (as I understand it).

Does any of this sound copasetic to you?

Is this how you would go about it?

Any help would be greatly appreciated and the more input would be helpful.

Thanks so very much.

[olddog]

Just because the warrenty time period is up, it doesn't mean that the company doesn't care about you and their reputation. Call them and explain what is going on. They likely still have records on the build. Even if they did not make any mistakes they can tell you what you need. If they did make a mistake, they may well make it right.

It is in there interest to have happy customers.

[olddog]

Originally Posted by Prestidigitator

He tells me there is about 6-9 different combinations he is going to try to get the motor to balance without taking the transmission apart and taking off the flex plate (as I understand it).

Does any of this sound copasetic to you?

There are three possibilities:
The engine is zero ballanced
The engine is 28 oz off set ballanced
The engine is 50 oz off set ballanced

Some of the ballance is done on the harmonic ballancer on the front and some is done on the flaywheel/flex plate on the back of the engine.

I suspect the fellow is planning to use different ballance sets on the front and back of the engine. Like mixing a 28 oz on the front and a 50 oz on the back or some other combination. Anyhow that is the only way I can come up with the number of combinations that you said.

I would not go down the road of mixing something different on the front from what is on the back. Both front and back need to be the same type of ballance. I am assuming that no manufacturer would be stupid engough to actually ballance an engine with a 28 oz on the front and a 50 oz on the back or some other combination.

If after trying a zero, then a 28 oz, and finally a 50 oz, (same on front and back each time), and it still does not ballance out with any combination, only then would I suspect something stupid has happened. However before that I would question that all the plug wires are in the propper order and that the engine is running correctly.

A ballance issue will get better and worse at different rpms, where the worse spots will happen at certain harmonics. For instance the bad spots may be at 2000, 4000, and 6000 rpm (I pulled those numbers out of my arss).

[xena2006]

Don't know if you are talking about Ford Racing, but had same problem with a 302 and it was a bad crankshaft. They refunded my $$ and I bought new motor. A big pain in the ass.

[Prestidigitator]

Originally Posted by olddog

There are three possibilities:
The engine is zero ballanced
The engine is 28 oz off set ballanced
The engine is 50 oz off set ballanced

It is a 28 oz externally balanced per the motor company.

I suspect the fellow is planning to use different ballance sets on the front and back of the engine. Like mixing a 28 oz on the front and a 50 oz on the back or some other combination. Anyhow that is the only way I can come up with the number of combinations that you said.

As I understand it he says that both the balancer and the flexplate are 28 oz.

That's why I put this question to the masses here.

It did indeed dyno smooth.

Yet, in my car it's very rough.

So, from what I can gather being posted here if the balancer and the flexpate match the crankshaft there really isn't any "combinations" that he can try?

Correct?

Such as 28.5 oz flexplate as opposed to 28oz EXACTLY?

The reason why I ask is I'm wondering if the guy is just trying to run up my bill or something.

He also stated he was going to try these "combonations" WITHOUT taking the transmission out.

Both front and back need to be the same type of ballance.

That's what I thought all along.

I am assuming that no manufacturer would be stupid engough to actually ballance an engine with a 28 oz on the front and a 50 oz on the back or some other combination.

Yeah, I don't think this is the case at all.

This is a pretty big well known crate motor company.

If after trying a zero, then a 28 oz, and finally a 50 oz, (same on front and back each time), and it still does not ballance out with any combination, only then would I suspect something stupid has happened.

Just so I know with 100% accuracy here. You are saying that it has to be 28 oz EXACTLY on both the front and rear?

However before that I would question that all the plug wires are in the propper order and that the engine is running correctly.

Thanks for the heads up and I will have him re-check this but I have had myself and a few sets of eyes on this motor and nobody has come up with this one.

[olddog]

If it did indeed dyno smooth, then the ballance had to be right at that time. The ballance does not change. The only thing that could have changed is the harmonic ballancer on the front and the flexplate/flywheel on the back. For high performance purposes, most say you should have the engine ballanced, with the parts you are going to use when the engine is installed.

I think you said, from the pictures, the harmonic ballancer is the one that was used during the dyno work. That only leaves the flexplate. Did it get changed?

I'm more of a book worm than actual engine experiance. I have built a few engines, most a long time ago. I have been around some racing stuff and know people in many different types of racing. So be ware that I am not an expert. Ususally my troubleshooting instincts are good, but some times I am dead wrong.

With that said, it is my belief that the damper and flexplate for a 28 oz off set has some spec on where and how much it is supposed to be off ballance. I do not know what that spec is, but many people do. I have never heard of anyone adding to or taking from the ballance on those parts. I'm sure there is slight variation from part to part. It would make sense to me that someone might make a slight change to get these part dead on, if they were at the far side of the spec, but I never heard of anyone doing it. That is why they say ballance the engine with the part you are going to run.

The slight variance in ballance from one damper or flexplate to the next might make the differance in an all out race engines life span, but it is not going to be felt. So if you have the correct parts on the engine that it was ballanced for, you will not feel any vibration.

This brings me back to what changed. It is possible to cross two plug wires and the engine not backfire. This will cause a noticable vibration. A dead cylinder from a bad plug or wire will cause a vibration. That is why I question if the engine is running correctly. The more radical the cam the less noticable a dead cylinder.

If that didn't answer your questions fire them back at me and I'll try to answer them one at a time. There are lots of guys on this forrum that are masters in this trade. They may chime in. If I tell you wrong, I think someone will correct me (hope so).

[Keithc8]

Is this a standard shift car? If you have a standard shift and the pressure plate was not balanced on the flywheel and marked this could be your problem. I know most Cobras are standard shift and use a pressure plate. I have seen these pressure plates cause a out of balance problems. If it is an automatic then this will not be an issue. If you are using solid motor mounts you will have some vibrating at different rpms. Good luck, Keith

[olddog]

I re-read this thread. You said the engine ran smooth on the dyno, but I get the impression you were not actually there. You only saw a video of the dyno.

I have only walked up and toughed one engine dyno in my life. If my failing memory of what I saw is correct, the engine pretty much bolts up hard to the dyno. There are not rubber or flexable mounts. I'm not sure you could see vibration by watching a video of a dyno. Therefore I do not think you can say for cetain that the engine ran smooth on the dyno.

My other thought is listen to the sound of the engine, especially at idle. Does it still sound the same? This may clue you in as wether or not it is running correctly.

Good luck

[olddog]

I see Keith popped in. Keith is my dyno comments above correct?

[Keithc8]

You can mount the engine with rubber mounts like the factory ones or with solid ones. This just depends on the company and their engine mounts. If the engine was dynoed with the wrong balancer or flywheel you should be able to tell this when dynoed. I do not know if you could tell in a video or not. I would make sure that I had the right flywheel or flexplate because they can get boxed wrong or mixed up.
You might have a miss in the engine causing this as well. I had a guy that had an exhaust pipe against the frame and he swore his engine was out of balance till he found this problem. This is the big problem with Fords and all of their differnet styles of balancing. Good luck

[Jerry Clayton]

I see you are from California---are you sure its not just an earthquake???

I have been balancing engines for over 30 years .

Is your car a stick or automatic?
How do you know it was your engine in the video?
Are your pulleys custom built or are there others like them?
Was your engine balanced/dynoed with the flywheel/flexplate that you have or was a change made to different one before install(((((many,many times, an externally balanced engine changes owners or planned vehicle install and the flywheel/flexplate will get changed for a different clutch /trans type))))))probably see that as much as 5% of the time
If flexplate, is it installed backwards???? clocked correctly on flywheel? takes some effort but by filing out boltholes can be done?
If it is a stick, and you have an aftermarket flywheel there should be a bolt on weight on the front side of the flywheel that will be opposite of the front balancer weight---if it has the weight---and is not opposite the front exactly, the flywheel is on wrong or the front balancer was put on without a key and has turned---
Is the front balancer an oem stock ford or an aftermarket one??????don't say fluiddamper

On the flywheel weight----if it is missing but you can see the bolt holes wwhere it goes, you can add the weight and see if that works or changed the weight to a different amount

if you can verify that changing weight on the flywheel changes the amount of shake---you can probably fix it by adding the right amount or if its a flexplate by changing to the correct one.

As for it being a miss----since 1958--- many missing/rough running fords had 3 plug wires installed incorrectly on the left bank---checking them would be the first thing I would do and the second would be verifying that the front balancer was on correctly by doing a tdc check

[G_Edmonds]

In the original post you said "flexplate" so I'm going to assume it has an automatic transmission. I had a similar situation lately and it turned out the torque convertor was out of balance.
Good luck.

[Prestidigitator]

Originally Posted by olddog

The slight variance in ballance from one damper or flexplate to the next might make the differance in an all out race engines life span, but it is not going to be felt. So if you have the correct parts on the engine that it was ballanced for, you will not feel any vibration.

I find this very interesting and this could be the key to what I’m driving at here (pun intended).

So let’s say you take a motor that is smooth running and balanced and you take off either or BOTH the balancer and flex plate and you replace them the proper balancer and flex plate but that of a different manufacturer.

Are you saying that you would not notice the difference or that there would not be much if any difference in the running of the motor?

If you are saying yes to this question then that would mean that there really are no “combinations” that this guy can try, correct?

Here’s the kicker that got me. He said he was going to try these “combinations” WITHOUT removing the transmission.

Originally Posted by Keithc8

If you are using solid motor mounts you will have some vibrating at different rpms. Good luck, Keith

Total Control motor mounts.

Originally Posted by Keithc8

You can mount the engine with rubber mounts like the factory ones or with solid ones. This just depends on the company and their engine mounts. If the engine was dynoed with the wrong balancer or flywheel you should be able to tell this when dynoed. I do not know if you could tell in a video or not. I would make sure that I had the right flywheel or flexplate because they can get boxed wrong or mixed up.
You might have a miss in the engine causing this as well. I had a guy that had an exhaust pipe against the frame and he swore his engine was out of balance till he found this problem. This is the big problem with Fords and all of their differnet styles of balancing. Good luck

Thanks Keith.

According to the guy who has my car now EVERYTHING matches up, balancer and flex plate.

I know nothing of dynos, but assuming that the engine was dynoed where it would NOT be possible to tell if there was a balance issue, is it possible that the motor company could have built, dynoed and then boxed up the motor without realizing that it was out of balance?

Also here is another scenario that has crossed my mind. Is it possible that they sent it out balanced correctly but it got handled rough in shipment and it sent it out of balance?

I will for sure have him re-check anything that has to do with ignition problems.

Originally Posted by Jerry Clayton

I see you are from California---are you sure its not just an earthquake???

LOL!

Nah, that was the first thing I checked. Pretty sure it wasn’t that.

I have been balancing engines for over 30 years .

Is your car a stick or automatic?

Automatic

How do you know it was your engine in the video?

It had my brackets and pulleys on the front, it’s unmistakable.

Unless of course they dynoed a motor with my stuff then pulled it off and put it on another motor, which, obviously is highly unlikely?

Are your pulleys custom built or are there others like them?

Zoops brackets and pulleys and yes there are many others like them.

Was your engine balanced/dynoed with the flywheel/flexplate that you have or was a change made to different one before install(((((many,many times, an externally balanced engine changes owners or planned vehicle install and the flywheel/flexplate will get changed for a different clutch /trans type))))))probably see that as much as 5% of the time

99.9% sure it is a DIFFERENT flex plate then the one they used to dyno the motor with.

I didn't see ANY flexplates hanging on the wall in the background and he made it sound as if they just take a flexplate that they have new in a box and ship it along with the motor.

And as I remember that was the case when I recieved the motor. It was new in a box.

If flexplate, is it installed backwards???? clocked correctly on flywheel? takes some effort but by filing out boltholes can be done?

Hmmm… can’t say with 100% accuracy but I will have him check this.

Are you saying it’s possible to install a flex plate backwards with ease?

If it is a stick, and you have an aftermarket flywheel there should be a bolt on weight on the front side of the flywheel that will be opposite of the front balancer weight---if it has the weight---and is not opposite the front exactly, the flywheel is on wrong or the front balancer was put on without a key and has turned---
Is the front balancer an oem stock ford or an aftermarket one??????don't say fluid damper

Sorry, being the novice I am I got lost here a little.

Not exactly sure what you are saying. Also, It is a professional products balancer and it has a counterweight.

On the flywheel weight----if it is missing but you can see the bolt holes wwhere it goes, you can add the weight and see if that works or changed the weight to a different amount

if you can verify that changing weight on the flywheel changes the amount of shake---you can probably fix it by adding the right amount or if its a flexplate by changing to the correct one.

It’s sounds to me like you are stating that if it’s a flywheel you can play with the balance and if it’s a flex plate you get what you get, correct?

As for it being a miss----since 1958--- many missing/rough running fords had 3 plug wires installed incorrectly on the left bank---checking them would be the first thing I would do and the second would be verifying that the front balancer was on correctly by doing a tdc check

I will advise him to these probable issues.

Originally Posted by G_Edmonds

In the original post you said "flexplate" so I'm going to assume it has an automatic transmission. I had a similar situation lately and it turned out the torque convertor was out of balance.
Good luck.

Interesting, this has never been brought up.

I'll see what he has to say about this as well.

Thank you to everyone who has chimed in this has been a learning experience and I look forward to your responses.

Thanks again.

[Jerry Clayton]

Flexplates usually have the extra weight welded on ---stick flywheels will use a bolt on piece--

[CobraEd]

Supposedly you can tell if you have a newer 5.0 crank that requires 50oz weight vs the older 302 crank that requires 28oz weight by looking at the throws and counterweights of the crank. I know people who can tell. I'm sure that keith can tell you. So, just take the pan off and look at the crank. See what it requires, and then start to determine if you have the right dampner and flywheel. Do you know the manufacturers??? Can you see a part number??? I so, call them up and ask them what the weight is.


.

[Jerry Clayton]

My suggestion---contact the engine builder with your serial /invoice number and ask what it was balanced with---get one of those and install it--run the engine without the converter or trans hooked up to see if its smooth---check to see it the nose of the converter fits the crank id properly---if so bolt the trans back in----

But first I would check to see that the front dampner is indexed correctly and has a key as that is easier than yanking the trans--- in otherwords,you must check and verify both ends

[olddog]

Originally Posted by Prestidigitator

So let’s say you take a motor that is smooth running and balanced and you take off either or BOTH the balancer and flex plate and you replace them the proper balancer and flex plate but that of a different manufacturer.

Are you saying that you would not notice the difference or that there would not be much if any difference in the running of the motor?

If you are saying yes to this question then that would mean that there really are no “combinations” that this guy can try, correct?

Yes. I think the differance in ballance would be negligable to a street car. In a race engine that is going to run 7-8K rpm all day, it could be the differance between finishing the race or not. Even then I would think you would have to be pushing the engine to near its limit before it would matter, and racers do push 'em to their limits.

Originally Posted by Prestidigitator

I know nothing of dynos, but assuming that the engine was dynoed where it would NOT be possible to tell if there was a balance issue, is it possible that the motor company could have built, dynoed and then boxed up the motor without realizing that it was out of balance? .

From what Keith said, a dyno operator should notice a ballance issue even if on solid mounts. You haven't realy said how bad the ballance issue is. The worse the problem the less likely this is it. You said this is a decent company, so this is not very likely, but I would not 100% rule it out. If all other possibilities are completely ruled out, this is what you will be left with.

Originally Posted by Prestidigitator

Also here is another scenario that has crossed my mind. Is it possible that they sent it out balanced correctly but it got handled rough in shipment and it sent it out of balance?

No. To ballance an engine, metal is remove (by drilling) or added (by welding in mallory metal) to the crankshaft. Nothing short of this will change the crank shaft. The damper on the front does have a rubber bushing (for lack of the correct term) that it is possible for the outer metal hub to slip. It happend to old deteriorated junk, but doubtful it could happen to a new one. Several people have mentioned that if the key is missing from the keyway on the damper, the damper could have rotated on the crank, causing it to be off ballance. This is a real possibility.


Good luck

[PANAVIA]

Also there could be something wrong somewhere else.

-- question; is this engine hooked to anything in the car right now>?

--some of the worst vibrations have been from transmission problems (even in park or N' ) ..

Have you fired up the engine with the trans disconnected >? IE: bell-housing and engine only with its stuff ...

[ceslaw]

For what it is worth, I put a 28 ounce flywheel on my crate engine, the builder having confirmed in writing it was a 28 ounce balance. Finished the car. Took it to the track. Vibrated something terrible above 2500 - 3000 RPMs. Sidelined the car. Called the builder the following Monday. "Oh that is a zero balanced engine. Yup, positive. Zero balance." Tore it all apart. Sent the flywheel back to get it zero balanced. Put it all back together. Vibration gone.

So big crate engine builders can goof.