Crank/balance identification

[Cmaxx252]

I'll try to keep the back story short.
The engine that came with my bronco (rebuilt and on an engine stand) does not have a spec sheet. My father (the one who purchased the engine years ago) lost the spec sheet.
The engine came with no balancer or flywheel. What he does remember from the add and talking to the owner of the engine shop that built it back then, was that it was balanced and blueprinted.
Engine casting numbers: E5AE-C3B - 1985-86 302 windsor block 2 bolt mains.
Crank casting number: 2MAE - 68-71 3.00 stroke 302 (50oz balance - external)

Dumb question incoming - With the crank being the mid 80's and 50oz, Would I be ok running my early flywheel (28oz) with my balancer set at 28oz as well?
None of the paint markings on the crank indicate a specific balance. Does that matter as long as I have the flywheel and balancer that match each other?
The weight removal holes had some flashing still on them. Is this typical with weight reduction for balance from the factory or does this look like work from a machine shop?
Do the other casting numbers mean anything? #85, C30, SMW, E7AE-AA?

 

[DirtDonk]

No. Never under normal circumstances.
Without knowing that the custom engine builder did something to the imbalance factor of the crank, you have to go by by the known numbers.

Someone else will be able to confirm those numbers, but for your basic purposes of an answer to your question, there is no way that a 28 ounce flywheel and damper will work with a 50 ounce crank.
All three must match, not just both ends.

It’s an “imbalance” factor, not a balance factor.
Ford added more weight to the crank in certain areas, and that extra weight must be offset at the flywheel and damper.
So a 28 ounce crank uses 28 ounce flywheel and damper. A 50 ounce crank uses 50 ounce flywheel and damper.
Period…

Again, unless the crank was customized.

 

[Cmaxx252]

No. Never under normal circumstances.
Without knowing that the custom engine builder did something to the imbalance factor of the crank, you have to go by by the known numbers.

Someone else will be able to confirm those numbers, but for your basic purposes of an answer to your question, there is no way that a 28 ounce flywheel and damper will work with a 50 ounce crank.
All three must match, not just both ends.

It’s an “imbalance” factor, not a balance factor.
Ford added more weight to the crank in certain areas, and that extra weight must be offset at the flywheel and damper.
So a 28 ounce crank uses 28 ounce flywheel and damper. A 50 ounce crank uses 50 ounce flywheel and damper.
Period…

Again, unless the crank was customized.

10-4 thank you. The short and logical answer im thinking is, go with the casting numbers identified on the crank, with it being 50oz, and get the correct flywheel to match it. My balancer is adjustable so i can add the weight bars for 50oz.

 

[Broncobowsher]

See if I can describe this a little further...
A traditional neutral balance engine has all the counterweighting inside the oil pan. The counterweights are needed to counterbalance the mass of the rod end of the crankshaft and some of the weight of the rod/piston.
In making the small block as compact as possible some of that counterweight mass was moved to just outside of the oil pan. The engine can be more compact if you don't need to make space for all the counterweight inside. The flywheel and damper are going onto the engine anyway, so shift a little of the counterweight there. Makes the engine more compact and lightweight. In general it is considered best practice to fully counterweight the crankshaft internally. I've seen an F1 crankshaft and the counterweights are bolt on, super cool stuff. But for a mass produced engine, overall weight reduction and it is good enough, Ford did the external balance. And in the early 80s they changed it to optimize something that we just don't care about.

When you see the number like 28.8 oz-in, that is mass times distance from centerline. 28.8 ounces one inch from the centerline, 1 ounce 28.8 inches from the centerline, 7.2 ounces 4 inches from the centerline. The indexing matters as well. And it could also be the lack of mass across from the needed spot. The drilling holes to reduce mass is very much the same as adding mass, just across from each other.

Now this is done at both the front and the back of the engine. Ford did the same counterbalance at front and rear. So whatever the crankshaft calls for, it needs that same value at the front (the damper) and the back (the flywheel)

 

[DirtDonk]

And just for your information Cmaxx, not that it has anything to do with this discussion, but for future reference, should you ever work on a 351W, you can reuse your old 302’s damper and flywheel.
The 351 Windsor remained 28.8 ounce for its entire run.
At least from an imbalance standpoint. It’s likely a 351 used a different damper, diameter, or resonant frequency, or whatever the criteria were, but it would still work.

 

[Cmaxx252]

And just for your information Cmaxx, not that it has anything to do with this discussion, but for future reference, should you ever work on a 351W, you can reuse your old 302’s damper and flywheel.
The 351 Windsor remained 28.8 ounce for its entire run.
At least from an imbalance standpoint. It’s likely a 351 used a different damper, diameter, or resonant frequency, or whatever the criteria were, but it would still work.

I wouldve preferred that for sure. When the original 302 was pulled, he donated it to the junkyard for a 5.0 out of a mustang. With all of the accessories still bolted to it :-/. luckily, the trans and transfer case were already out of the bronco and in storage so I still have those.
This current engine was something later he came upon and purchased, but over the years lost the spec sheet for it. So Im trying to gather all the info to get it back together correctly. I'm learning as I go. Thank you for the input though on the 351W. I like the 289's and 302's haha.
Do you know a thread that someone has stated the part number for a good 50oz flywheel used with the later block with the 11" clutch? Im running the original rat 3 speed, original 3 finger style clutch.

 

[73azbronco]

your easiest bet might be, unbolt the crank, take it in and find what balance it is.

 

[Broncobowsher]

your easiest bet might be, unbolt the crank, take it in and find what balance it is.

But you would also need to take in the rods and pistons to really know.

 

[jamesroney]

But you would also need to take in the rods and pistons to really know.

It’s a 2MAE crank that looks factory drilled and hasn’t been welded, so it doesn’t have any Mallory metal in it. So it’s a 50 oz-in crank. It will have a 1 piece rear main seal, and no rear main flange under the cap. It will have no knurl for a rope seal.

The flywheel for an 85 Bronco with a 302 is the one you want. ATP-Z299 Don’t pay more than about $100 new. The aftermarket one is drilled for both long, and diaphragm clutch pattern.

The 289, early 302 and 351W is 28.2 In-oz imbalance. IDK why people are saying 28.8???

 

[73azbronco]

But you would also need to take in the rods and pistons to really know.

mmmmmm, maybe not. i built more than a few, but admit I farmed out balancing. I think they do the crank as it has heaviest moment, then refine the pistons individually. And, if you pull the crank, might as well pull the pistons.

 

[spap]

I’ve had a few engines (5.0) balanced and they had more small drill marks along the crank small ones, but it depends on the balancer
worst thing is to out it together and start it and you have a vibration.
I'm wired that I would take out the crank rods pistons, balancer and flex to a balancer and have it done, then you know for 100% and then can spin it up to 6500 no probs. Haaa