383 - 432 Issues

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73smallblock

73smallblock

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Yesterday I went to help a friend assemble his 383/432 build. I put the bearings in to check clearances and set the crank in the block. As soon as I set the crank down I noticed it was tight. The radius on the oil diverter(or whatever it's called) that's built into the crank is hitting the casting right before the rear main seal. I pulled the thrust bearing out and it moved forward enough to clear. The issue is, you would have to take off about .020-.030 for the thrust bearing to clear. So the front side of the thrust would have a bunch of clearance due to the crank moving forward. The other issue is with moving the crank forward, now the other mains are basically against the radius on the other journals and the bearing is not centered on the journal. Has anyone ran into this issue?

The rotating assembly is a full scat kit, not a ground 440 crank. Block is a 1962. Thanks for any help. If I can, I will try and run over and get some pictures.
 
Here are some pictures
With thrust installed
PXL_20250309_133436225.jpg

Gap flavors front
PXL_20250309_133506481.jpg

Bearing location with thrust installed
PXL_20250309_133545065.jpg

Thrust bearing removed
PXL_20250309_133633466.jpg

Removed, now has clearance
PXL_20250309_133646557.jpg

Bottom thrust just to show how much it needs to move
PXL_20250309_133722070.jpg


PXL_20250309_133725980.jpg
 
If I remember correct the assembled thrust is only a few thousandths. (.002-.007”). You may have put the crank in and measure clearance without the bearing then measure thrust bearing thickness. Usually you have to tap the crank forward to seat the thrust bearings against the block. But I think I’d be more worried about the crack at the bottom of the cylinder in picture 4. If I’m seeing it correctly.
 
Yes, that would be the correct measurement on the thrust. With the thrust in place there is no movement because it's hitting in the block. Those pictures are with about .005 lapped off the back of the back of the bearing. My concern is if I keep lapping material off the bearing, the front side is going to have a of clearance. What if the crank moves back and starts to run the block where it's hitting now? And it's moving the bearings really close to the fillet. That is not a crack but a casting line. The block was checked.

Is it acceptable to clearance the block back there or will it cause excessive pressure on the rear main?
 
I’m not an expert but to me shaving the bearing means it would have to have both halves of the bearing shaved the same amount. The crank will thrust forward. The second picture looks like the right side is aft, there appears to still be clearance between the bearing and block. I’d put the thrust cap on with the upper and lower bearing snug but don’t torque it tap the crank forward from the back and see what the actual thrust is then see where the slinger at the back of the crank is
 
If You have the stock 383 crank, take some reference measurements, may need to send that crank back.
 
Yup. Drop the old crankshaft in the block with bearings and you’ll prove instantly the bearings are fine.
 
73smallblock said:
Yesterday I went to help a friend assemble his 383/432 build. I put the bearings in to check clearances and set the crank in the block. As soon as I set the crank down I noticed it was tight. The radius on the oil diverter(or whatever it's called) that's built into the crank is hitting the casting right before the rear main seal. I pulled the thrust bearing out and it moved forward enough to clear. The issue is, you would have to take off about .020-.030 for the thrust bearing to clear. So the front side of the thrust would have a bunch of clearance due to the crank moving forward. The other issue is with moving the crank forward, now the other mains are basically against the radius on the other journals and the bearing is not centered on the journal. Has anyone ran into this issue?

The rotating assembly is a full scat kit, not a ground 440 crank. Block is a 1962. Thanks for any help. If I can, I will try and run over and get some pictures.
Click to expand...
Are all of the bearings champhered ?
 
This looks like an aftermarket crank & the dimensions are wrong, causing the alignment problem.
 
MOPARMAGA said:
Are all of the bearings champhered ?
Click to expand...
They are regular berings. Unfortunately the kit was shipped without main bearings but the rod bearings were in the box. Summit and scat were of no help to say what bearings came with the kit. The only chamfered you can get are ones that 440 source puts a chamfer on with a fixture they made to do so. Those bearings are on the way but the problem to me is something is out of spec. Like the distance from the center of the crank (thrust journal) to the oil slinger is off.
 
73smallblock said:
They are regular berings. Unfortunately the kit was shipped without main bearings but the rod bearings were in the box. Summit and scat were of no help to say what bearings came with the kit. The only chamfered you can get are ones that 440 source puts a chamfer on with a fixture they made to do so. Those bearings are on the way but the problem to me is something is out of spec. Like the distance from the center of the crank (thrust journal) to the oil slinger is off.
Click to expand...

Doesn’t that crank require chamfered bearings,,,it looks like a radius on the journal to me .

Tommy
 
Those are some very good pics,,,,shows clear details.
The block can be relieved very easily right there,,,,if you need to .
That area is for the flange to keep excess oil from the rear seal ,,,,,you won’t compromise that by putting a radius in the lip there .
But get the right bearings and double check everything,,,,,you might be alright as it is .

Tommy
 
Desoto291hemi said:
Those are some very good pics,,,,shows clear details.
The block can be relieved very easily right there,,,,if you need to .
That area is for the flange to keep excess oil from the rear seal ,,,,,you won’t compromise that by putting a radius in the lip there .
But get the right bearings and double check everything,,,,,you might be alright as it is .

Tommy
Click to expand...
Like I said the ones that 440 source modifies are on the way. As for scat, they say that it just uses a p-bearing, which is what those are. We will try them but just trying to get a plan together in case that doesn't work. I think I .010-.020 chamfer on the edge of the casting will get taken care of it.
 
With all upper bearings and crankshaft in the block but no main caps installed you can see the radius of the crankshaft and the edge of bearings. Does it look like any bearings are into the radius, pushing crankshaft? If not, and if every other dimension of the crankshaft is correct I would think chamfering the block and cap to clear that slinger should be fine.

That side of slinger does appear to have quite a large radius of its own where the interference is.
 
With the thrust installed no, the bearings aren't hitting the radius on the crank, just the crank rubbing the block. That's why I think the block need clearanced because of the crank moves forward to clear the block, then the bearing is just touching the radius on the crank.
 
That looks like a lot of thrust clearance, by looking at the crank sitting in the bearing
 
73smallblock said:
They are regular berings. Unfortunately the kit was shipped without main bearings but the rod bearings were in the box. Summit and scat were of no help to say what bearings came with the kit. The only chamfered you can get are ones that 440 source puts a chamfer on with a fixture they made to do so. Those bearings are on the way but the problem to me is something is out of spec. Like the distance from the center of the crank (thrust journal) to the oil slinger is off.
Click to expand...
I think your right, that radius is to wide or tall.
Ill go out and take a look at a crank soon.
 
NC Engine Builder said:
That looks like a lot of thrust clearance, by looking at the crank sitting in the bearing
Click to expand...
Is it normal to have to take .030 off the one side of the thrust surface? What about the excessive clearance on the opposite side? I've never had to take that much off before, that's why I'm asking.
 
73smallblock said:
Is it normal to have to take .030 off the one side of the thrust surface? What about the excessive clearance on the opposite side? I've never had to take that much off before, that's why I'm asking.
Click to expand...
No, that's not normal. You could easily chuck the crank in a lathe and trim that slinger flange, but it looks like you will still have a thrust issue
 
NC Engine Builder said:
No, that's not normal. You could easily chuck the crank in a lathe and trim that slinger flange, but it looks like you will still have a thrust issue
Click to expand...
I could chuck it up and cut it but didn't know if that would weaken the crank any. I think that once the crank is able to move back, it will solve the thrust issue.
 
It's hard to read that but is it saying that the o.d. of the flange is oversized? Like it would need turned down to fit properly?
 
73smallblock said:
Yes, that would be the correct measurement on the thrust. With the thrust in place there is no movement because it's hitting in the block. Those pictures are with about .005 lapped off the back of the back of the bearing. My concern is if I keep lapping material off the bearing, the front side is going to have a of clearance. What if the crank moves back and starts to run the block where it's hitting now? And it's moving the bearings really close to the fillet. That is not a crack but a casting line. The block was checked.

Is it acceptable to clearance the block back there or will it cause excessive pressure on the rear main?
Click to expand...
I ain't sure I understand this , but you ain't gonna get nothing right unless the thrust bearing is right , surely its no 3 on that block too...
you don't have the no 3 main in backwards do you ??
 
Honestly it's such a non coherent run on sentence I'm not sure what they are trying to say. It almost reads that the flange OD should be 3.43 and if it's not, there is some other bearing
 
I will have to take a look at that. Thank you for your suggestions
 
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