1984 bronco 351w flex plate issue

[akies32]

I’ve got serious flex plate issues.. I bought this bronco for cheap with a newly rebuilt motor. Motor seems strong but who ever installed it did not know what they were doing..
it’s appears I have a 50oz balancer, 14.5” 164 tooth flexate, c6 transmission, and a torque converter that has a 8” bolt pattern. Please see pics below. Do I need to change the balancer to a 28oz?
If I can get a flex plate that will bolt up to the torques convertor will the c6 trans be ok running with 50oz imbalance?
Looking for some clarity here so I can do it right and actually be able to start the dang thing

 

[DirtDonk]

The transmission doesn’t care what the imbalance factor is. Only the engine needs that taken into account.

First, you need to absolutely verify that it’s a 351W. If you know that already, then you need to either determine the crankshaft wasn’t changed (such as with a stroker conversion) or go ahead and assume it’s a standard crankshaft and get BOTH a 28oz damper and a 28oz 164t flexplate.

Sorry I didn’t look at the pictures yet, but wanted to put out the basics as I know them at least.

 

[DirtDonk]

Maybe they are there and I don’t see them on my small screen, but can you post the engineering numbers that you find on the parts?
Or any numbers you find actually.
Thanks

 

[akies32]

The transmission doesn’t care what the imbalance factor is. Only the engine needs that taken into account.

First, you need to absolutely verify that it’s a 351W. If you know that already, then you need to either determine the crankshaft wasn’t changed (such as with a stroker conversion) or go ahead and assume it’s a standard crankshaft and get BOTH a 28oz damper and a 28oz 164t flexplate.

Sorry I didn’t look at the pictures yet, but wanted to put out the basics as I know them at least.

How can I verify the crankshaft was or was not changed? I’m assuming it has just by what the previous owner told me. Can I tell if I pull the pan?

 

[Broncobowsher]

351W doesn't have a balance change. That is a 302 only change. You can't put a 302 crank in a 351 block. If you tried, you would be using a yardstick instead of a micrometer to measure the bearing clearances.

 

[DirtDonk]

But what about stroker cranks? Some for the 302 are zero-balanced. Can that be the same way for 351 based strokers? Or are they all going to be 28oz no matter what?

Paul

 

[akies32]

But what about stroker cranks? Some for the 302 are zero-balanced. Can that be the same way for 351 based strokers? Or are they all going to be 28oz no matter what?

Paul

That’s what I’m worried about. I know this engine has been rebuilt and according to the last guy is was now a 400m. Which could be the reason for the 50oz balancer.

I ran the engine previously and it was smooth. No vibration. The problem was the start not engaging

 

[hucklburry rev2]

Here is a bit on the starters, if it ran smooth with that flexplate, I wouldn't change it. Perhaps you can double check dimensions and the starter you used, with the info from there?

https://static.speedwaymotors.com/pdf/91067430.pdf

 

[akies32]

Here is a bit on the starters, if it ran smooth with that flexplate, I wouldn't change it. Perhaps you can double check dimensions and the starter you used, with the info from there?

https://static.speedwaymotors.com/pdf/91067430.pdf

Ok that’s actually makes some sense. I going to try a manual starter tomorrow morning

 

[DirtDonk]

That’s what I’m worried about. I know this engine has been rebuilt and according to the last guy is was now a 400m.

Just to be accurate here, there’s no such thing as a 400M. Never was, and you can’t get there from here if you start with a Windsor.
You can start with a 351M, and easily turn it into a 400 (still doesn’t make it an “M”). But you can’t change a 351W into something resembling a 400 (but it’s still a “W”) without stroking it.

Which could be the reason for the 50oz balancer.

They don’t change the imbalance factor on 335-series engines (351M, 351C, 400) no matter the year or displacement.

I ran the engine previously and it was smooth. No vibration. The problem was the start not engaging

Then it’s not a mismatch of parts. If they worked before, then they are the correct type.
Doesn’t mean something can have been damaged, however.

Can you post up a couple of overall pictures of the engine, just so we can see what family of vengeance it belongs to in the first place. Specifically close-up of the area under and around the distributor.
From one of your pictures, it looks like a later model Windsor. But to know exactly what it is, you’ll have to get some casting dates and part number information from the area behind the starter.

 

[akies32]

Just to be accurate here, there’s no such thing as a 400M. Never was, and you can’t get there from here if you start with a Windsor.
You can start with a 351M, and easily turn it into a 400 (still doesn’t make it an “M”). But you can’t change a 351W into something resembling a 400 (but it’s still a “W”) without stroking it.

They don’t change the imbalance factor on 335-series engines (351M, 351C, 400) no matter the year or displacement.

Then it’s not a mismatch of parts. If they worked before, then they are the correct type.
Doesn’t mean something can have been damaged, however.

Can you post up a couple of overall pictures of the engine, just so we can see what family of vengeance it belongs to in the first place. Specifically close-up of the area under and around the distributor.
From one of your pictures, it looks like a later model Windsor. But to know exactly what it is, you’ll have to get some casting dates and part number information from the area behind the starter.

 

[hucklburry rev2]

Do you have a pic of the starter, the front snout that goes into the bellhousing, showing the gear?

 

[DirtDonk]

Now that I’m paying attention again, I clearly see that you said it was an 84. That’s possibly where some of the confusion of the previous owner comes in. Because the 351M was available until 83 I believe. Maybe even’84?
After that, it should’ve been a 351W. In theory…
I believe I’ve heard of some 351M’s coming in truck as late as 84, but I can’t remember those details.
But the fact that the block number is a “E4…“ means it is in fact, slated for 84 and later vehicles. So it would not be a 351M, and would be a Windsor as you suspected.
One of the part number gurus can interpret the numbers more accurately.

 

[ba123]

I'm not one of those gurus, but a search says the block is a 351W.

Who built the engine? Maybe ask them if possible? And yes strange that it has a 50oz imbalance but you can build an engine with any imbalance you want, is my understanding...you just have to be consistent on both ends.

And the flexplate damage would just mean you used the wrong starter for that flexplate. You need a starter for a 164 tooth flexplate if that's what it is.

 

[DirtDonk]

Or it was a crappy starter to begin with, I suppose is another possibility.
And how exactly are you determining that it’s a 50 ounce imbalance part? Very hard to do by looking at it.
You’ll need to check part numbers on the flex plate and the damper, but chances are better than average that it’s still 28 ounce.
If it turns out, they are 50 ounce, and it ran smooth in its life, as said earlier, they are correct for the crank.
Because it would’ve shaken itself half to death immediately. In other words, you would’ve known right after the first start up.

 

[akies32]

Or it was a crappy starter to begin with, I suppose is another possibility.
And how exactly are you determining that it’s a 50 ounce imbalance part? Very hard to do by looking at it.
You’ll need to check part numbers on the flex plate and the damper, but chances are better than average that it’s still 28 ounce.
If it turns out, they are 50 ounce, and it ran smooth in its life, as said earlier, they are correct for the crank.
Because it would’ve shaken itself half to death immediately. In other words, you would’ve known right after the first start up.

I watched this guys video to determine

 

[akies32]

Do you have a pic of the starter, the front snout that goes into the bellhousing, showing the gear?

 

[akies32]

I’ve got serious flex plate issues.. I bought this bronco for cheap with a newly rebuilt motor. Motor seems strong but who ever installed it did not know what they were doing..
it’s appears I have a 50oz balancer, 14.5” 164 tooth flexate, c6 transmission, and a torque converter that has a 8” bolt pattern. Please see pics below. Do I need to change the balancer to a 28oz?
If I can get a flex plate that will bolt up to the torques convertor will the c6 trans be ok running with 50oz imbalance?
Looking for some clarity here so I can do it right and actually be able to start the dang thing

 

[akies32]

I did just find the plate had these gasket glued to it for some reason.

 

[akies32]

Ok I got a manual 302 starter off my mustang and it will only turn over if I take a hot wire directly to the start side of the solenoid and is really hard to turn over.. even with a 826ca battery.. barely turn over and won’t at all using the starter solenoid.

I’m really getting tired of this bronco. Please help