66 With Heavy Vibration

66Classic · Oct 25, 2017

Hello everyone, I recently purchased a 66 mustang that has had a 90-91 302 engine installed. There is some very heavy vibration felt in the car at 2000rpm and higher - even while in neutral. I've been told not to drive the vehicle as this shaking will damage the engine. Ofcourse the seller who sold me the car never mentioned this issue and I just thought it was how a old classic feels. After doing some research I have found out that either there is a wrong harmonic balancer or flywheel installed. In the worst case I may have a bad engine. I have gathered all the serial numbers off the engine (F16E) the serial number off the harmonic balancer (E4TE-A3A) and the flywheel (RF-E1ZR6380.) I also attached pictures of the serial numbers just in case I am not reading them correctly lol

If anyone has any knowledge about this vibration and can help that would be so greatly appreciated. Im hoping the harmonic balancer or flywheel is not correct and that I don't have an engine rebuild ahead of me. Any ideas?

horse sence · Oct 25, 2017

What transmission are you running ,and what fly wheel do you have ? You need the fly wheel balance same as the motor . If you have a vibration at idle ,it has to be balance is off

tos · Nov 2, 2017

What Horse says is true. If it is smooth below 2000 then maybe check your motor mounts to make sure one or both aren't bad allowing the engine to bounce around. Back in the 70s I busted a mount doing a high speed 2 gear downshift (I was 17). It vibrated like hell after that till I replaced my mounts.

66Classic · Nov 21, 2017

I am using a brand new harmonic balancer and flywheel both rated at 50oz. Ive replaced the clutch and driveline as well.
YET still excessive vibration. Some machine shops are saying I need an engine rebuild, while another shop told me they can almost guarantee its not the engine and to keep looking at what "additions" could be causing the vibration.

tos · Nov 21, 2017

People have different views of what "vibration" is. Is this something you can see the engine doing if you stood with the hood up and the engine was rev'ed up? Or is it something that makes a sound, Vibrating sound, or only something you can feel but not see?

General karthief · Nov 23, 2017

Just curious, what firing order are you using?

LILCBRA · Nov 23, 2017

Without knowing more specifics, I wonder if your balancer and flywheel are correctly balanced to the engine. The part number dates decode 1981 for the flywheel, 1984 for the balancer, and 1991 for the engine block. I believe that they made the switch from 28oz to 50oz balance in 1982? If that is correct, and assuming your crank is indeed the original crankshaft for that block, your flywheel may be incorrectly balanced for the engine if it was not previously rebalanced. I would inspect the flywheel a little more closely. This, of course, is also assuming that there is nothing mechanically wrong with anything else, i.e. no loose bolts or anything anywhere.

65-Fstbk · Nov 28, 2017

Just going on what's here I'd say it's likely part of the rotating assembly being out of balance. Is there any associated noise such as clunking etc especially at higher rpm? Does the vibration occur when the car is stationary with rpms up? If not you could have a drive shaft that's out of balance.

LILCBRA · Nov 29, 2017

65-Fstbk said:
Just going on what's here I'd say it's likely part of the rotating assembly being out of balance. Is there any associated noise such as clunking etc especially at higher rpm? Does the vibration occur when the car is stationary with rpms up? If not you could have a drive shaft that's out of balance.

Good question! I was making the assumption (we all know about that word, right?!?) that it was stationary. If it is in motion, it could very well be driveshaft related. Probably the most common and easiest to determine would be a bad U-joint. Bad or badly balanced tire? Driveline angle out of whack? You don't mention which transmission you have, so it could be something there too. Just a couple of ideas to chew on if it is a problem while in motion.....

66 With Heavy Vibration

66Classic

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horse sence

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General karthief

wonder how much it would cost to ship you a pair

LILCBRA

I wish I didn't have all of these balls in the air

65-Fstbk

LILCBRA

I wish I didn't have all of these balls in the air

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66 With Heavy Vibration

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wonder how much it would cost to ship you a pair

I wish I didn't have all of these balls in the air

I wish I didn't have all of these balls in the air

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