1966 mustang 289 Balance mystery

Wardy

Member
Aug 15, 2019
4
1
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49
Delaware
I have a 1966 mustang with a 289 and a balance issue. i have replaced the motor with engine code (05AE 6015E) i believe this motor is from a 64-65 Comet or Galaxy . So here is where it gets confusing, i am know i used the harmonic balancer from the 66 and put it onto the 64 motor. Since the i purchased a new harmonic balancer thinking that would solve the problem.. no it did not. Now i have moved to the flywheel. I believe i have a 50oz flywheel. To try to solve this mystery i have removed the trans and i intend on starting the car without the flywheel to see if i need to purchase a 0 balance flywheel. Is there a way i can determine what harmonic ballad and flywheel go with this crank without tearing the entire motor apart? Please help!

FYI.. I created this problem when i was 18, now here i am at 50 trying to fix it..lol

Wardy
 
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dennis112

10 Year Member
May 15, 2005
1,503
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Amish Wonderland of Central PA.
Um ...how will you start the motor with out a fly wheel ?
Valid point . . . . .

Since it was not mentioned, all small block Fords from their introduction in the early 60's until about 1981 have a 28oz imbalance. From then on the 351w retained the 28 ounce but the 303 went to 50oz imbalance. From then on the 351w retained the 28 ounce but the 302 went to 50oz imbalance. None ever came with 0 balance from the factory (which is a performance mod). I suggest finding the block casting # to help narrow down the year of the block or pulling the oil pan to get the casting # off the crank (preferred.)

Here's an idea--if you remove the flywheel, look to see if you can prominately see the motor's rear main seal. If can see it it is more than likely a 1 piece seal used from 1981 and newer (50oz imbalance.) If you can only see the rear main cap it is the older 28oz design crank.

One final note is that both the balancer and the flywheel must match in imbalance and any other combos will not work smoothly. The matched pair must also match the imbalance of the crank being used.

There is a little more involved concerning crank interchange and aftermarket cranks but I'd first verify the info above before spending more money.
 

Wardy

Member
Aug 15, 2019
4
1
13
49
Delaware
Valid point . . . . .

Since it was not mentioned, all small block Fords from their introduction in the early 60's until about 1981 have a 28oz imbalance. From then on the 351w retained the 28 ounce but the 303 went to 50oz imbalance. From then on the 351w retained the 28 ounce but the 302 went to 50oz imbalance. None ever came with 0 balance from the factory (which is a performance mod). I suggest finding the block casting # to help narrow down the year of the block or pulling the oil pan to get the casting # off the crank (preferred.)

Here's an idea--if you remove the flywheel, look to see if you can prominately see the motor's rear main seal. If can see it it is more than likely a 1 piece seal used from 1981 and newer (50oz imbalance.) If you can only see the rear main cap it is the older 28oz design crank.

One final note is that both the balancer and the flywheel must match in imbalance and any other combos will not work smoothly. The matched pair must also match the imbalance of the crank being used.

There is a little more involved concerning crank interchange and aftermarket cranks but I'd first verify the info above before spending more money.
Dennis, Thank you for your response. I am fully aware you cannot start the car without the flywheel. My intent was to figure out what I have in interchange the flywheel to see what one removes the vibration. This is the most expensive path.

Next question: is the flex plate and the Harmonic balance labeled to indicate the weight?

Thanks
 

2Blue2

I partied with that dude!, um girl, um whatever...
Mar 5, 2019
820
435
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Oahu
Since you have had this combo for 32 years (since 87 or so) and I assume it was used then.
C6Ae block most likely will need 28 imbalance damper and flex plate
 

dennis112

10 Year Member
May 15, 2005
1,503
20
69
Amish Wonderland of Central PA.
Next question: is the flex plate and the Harmonic balance labeled to indicate the weight?

Thanks
There are no stampings used that would indicate weight.

If you can find a casting # it might help to identify the year. Front and rear photos may be compared to those found on the web. If you are going to buy parts and you are sure you have a 289, get them for 28oz imbalance.

Are you sure the motor doesn't have a miss instead?
 

Wardy

Member
Aug 15, 2019
4
1
13
49
Delaware
Dennis, thanks agin for you response. This is what i learned today.

Casting # C5AE 6015E this is a 289 for a 1965 Ford Galaxie.
Date code is # 4K24 this was manufactured on October 2nd in 1964.

1. I have removed the flex plate, it is a 157 tooth that measures 13 and 1/4". this is for the small bell housing of the C4 trans. The flex plate has no part numbers at all. I still do not know if this is a 28 or 50 OZ plate.

2. I inspected the rear end of the crank, no part numbers.

3. The harmonic Balancer had part # 594-269. i font this online to be a direct replacement for stock 289 -1966 Mustang and the 1964 Galixie but the weight spec was not shown online.

Do you think it is safe to say my 1964-289 requires a 28 oz flywheel?

any help is appreciated.

Thanks

Wardy
 

2Blue2

I partied with that dude!, um girl, um whatever...
Mar 5, 2019
820
435
73
52
Oahu
it is safe to say my 1964-289 requires a 28 oz flywheel?
It is safe to say a 289 needs a 28 0z flywheel or flex plate and harmonic balancer, Disclaimer~ unless the crank was swapped for a 5.0 crank (which is doubtful but not impossible)

Post a pic of your mustang, We all live for mustang pics here.
 

dennis112

10 Year Member
May 15, 2005
1,503
20
69
Amish Wonderland of Central PA.
Yes it should be 28oz imbalance.

I doubt that the crank has been swapped out for a newer 5.0 as it (the 5.0) is designed to use a 1 piece crank seal. I don't think one can be used in the early block that you have.