[pony66]

Hi people,

I need to balance a 302 cui engine correctly, therefore I need your help:

I have a 66 mustang with C4 tranny and a freshly bought used 302 engine. The cast-number of the block is D90E-6015-E3A and the block has no one-piece seal at the back.

The damper coming with the engine is 28oz (cast no is D6ZE-6316-A2A) while the mounted flexplate was a 164 teeth 50oz for a AOD (50oz is my guess, code on the weight is "EOSP", size of weight is kind of small but there is a large hole in the plate on the opposite side of the weight)

The flexplate given to me as fitting for the engine and my C4 with small bellhouse now looks like some 28oz imbalance (157 teeth, no hole, size of weight similar to a 289 28oz flywheel).

As I was told everything would fit I put all together, the engine runs nice, but only if I do not raise rpms above about 2000...
At 2000 or maybe 2500 rpm the car starts shaking roughly. I immediately stopped the engine and now I am trying to identify the used parts correctly for replacing the misfitting parts.

I never heard of a combination of 28.2oz damper and 50oz Flexplate running fine...

Can you help me out of this mess? At the weekend I check the cast-no of the crank...
Any help is appreciated, many thanks in advance!

Bye,

pony66

 

[tonys10sec306]

you cant mix and match the diffrent blance weights.28oz flex plate is what you need

 

[dennis112]

Tonys right. Your late 70's block would require a 28oz flexplate/balancer if it has a 70's crank in it--which it probably does with the 2 pc. seal.

 

[pony66]

Thanks for your quick replies!

So you do not think of a (possibly revised) 302HO non-roller block carrying now a 50oz-balanced 302HO crank which has not been balanced correctly in the former car with the misfitting 28oz damper and the correct 50oz AOD-flexplate?
This is my actual guess and in this case the seller has been right with thy type of the engine but only a wrong damper has been used.
How smooth would a engine with wrong damper run?

 

[ckelly]

Not smooth. And you can't mix a 50 oz crank with 28 oz external parts. They all have to match. If the internals are mostly stock parts or stock replacement, there will be minimal balance issues. If he paid someone to balance the setup with the wrong parts - well, that's a mess. IF it's really a 82 and later 50 oz 302 crank, try getting a correct balancer on it.

 

[pony66]

Hi ckelly,

On 2006-03-31 09:27, ckelly wrote:
Not smooth. And you can't mix a 50 oz crank with 28 oz external parts. They all have to match. If the internals are mostly stock parts or stock replacement, there will be minimal balance issues. If he paid someone to balance the setup with the wrong parts - well, that's a mess.

Edit: I know that I can't (or shouldn't), but someone has if the parts were not changed after machines extraction from the car...

So if the engine ran fine in the car it was taken from, there is no way that it was in the setup
50oz crank
50oz flexplate
28oz balancer
?

IF it's really a 82 and later 50 oz 302 crank, try getting a correct balancer on it.

Thats what I will do after verifying the crank number...



<font size=-1>[ This Message was edited by: pony66 on 4/1/06 1:43am ]</font>

 

[ckelly]

So if the engine ran fine in the car it was taken from, there is no way that it was in the setup
50oz crank
50oz flexplate
28oz balancer
?

I would think not. Possibly at lower RPM enought to make it look OK. IIRC, there was a post here in the distant past where 28 oz parts ended up on a 50 oz crank and it was a "shook me like a dog" kinda thing.

 

[pony66]

Hi again,
short update to my question:

I finally got the crank-code: its 2MA which leads to a 28oz balanced simple 302 crank.

Now only a correct flexplate identification can help me out of this crap...
Can you help me with it? The upper plate is the one for the AOD which came with the engine, the other with the slightly bigger weight is the one claimed as 50oz to be used.
(edit: slightly means suggesting the same material one could calculate about 40% more effectiveness of the counterweight regarding size, thickness and position in no of inches from flexplates center so that we would have 50oz for the AOD and 28oz for the other...would this calculation prove anything?).

Is it possible that both plates are 28oz?

Many thanks for your help!

<font size=-1>[ This Message was edited by: pony66 on 4/11/06 2:41pm ]</font>

<font size=-1>[ This Message was edited by: pony66 on 4/11/06 3:53pm ]</font>

 

[ckelly]

Yes if the "AOD" flexplate is from a 351W large bell C4. That would be a 164tooth 28 oz part. All 351Ws use 28 oz. One other possibiity - there is a problem with the converter.

 

[pony66]

On 2006-04-11 07:50, ckelly wrote:
Yes if the "AOD" flexplate is from a 351W large bell C4. That would be a 164tooth 28 oz part. All 351Ws use 28 oz. One other possibiity - there is a problem with the converter.

The main problem here is that any "ifs" do not help in any way. I managed it to get the AOD plate compared with a AOD 164 teeth 50oz plate, they are exactly the same.
That makes it really clear that I reveived a "misconfigured motor-package".

What do you mean with "problem with the converter" ?
The car starts moving immediately, the ATF in converter and C4 has been changed completely, so I guess the converter should be as fine as before.

Thanks for your guesses and help.

 

[pony66]

Ok, things are getting closer...if you still are interested:

I tested an identified 28oz plate and still had vibrations.
I was told that the motor ran fine with the given 50oz AOD-plate and I believe in this. Unfortunately I had no large C4-bellhousing to test the large plate to finally verify the "good-running" configuration.

So it seems that the motor ran and would run with

28oz damper
28oz crank
50oz flexplate

This could probably work if the crank has been balanced for that.
In my opinion this would lead to a damaged crankshaft bearing after some time because of different imbalances on the two sides of the crank.
Is this guess right? If so I will return the motor immediately...this is not what I wanted...

 

[pony66]

Hi again, it seems that ckelly was right with his guess.

As I lately tried a new 50oz flexplate and the vibrations were even worse it seems that the 28oz crank has been balanced with the given 50oz flexplate.
In this case the motor would run only with this plate correctly. What a mess...

Thanks for all your help.