350 bearings questions

[KeyBlazer]

1973 K10, with a 350 V8.
Doing a Holley FI setup, headers, belt system
Motor is still in the truck, and I'm replacing the stock oil pan, with a winged pan, and one piece Oil pan gasket...
I have next to no history on this motor, except the truck was owned by one family since new, and they have all passed now.
I've owned it almost 18 years, ODO shows 56,000 miles, prob 30,000 in my care, but no idea how many time around that is.
I was told it was rebuilt, but no info if its the original, or a replacement.
Ran well with good oil pressure...

So I thought while the pan was off, Id pull a main and rod cap and see whats what..
Its a 4 bolt main which is correct for the 350 in 1973.

Main bearing looked ok, just some fine marks, but I popped the bearing off the cap to see what size it is.
Baffled now.
Main bearing says...
D.A.B. 86
8201 CAP L
3-39 A
4-39 DA 49

No idea what that means for size... and a good internet search gave me no info.

Pulled a Rod cap...
Again, bearing and journal look OK, with fine scratches, nothing serious.
Pulled the bearing from the rod cap, and the marking are:
D.A.B. 51
7555 CAP
6-30 C1
6-30 DA-41

Anyone enlighten me on how to read these markings?

 

[JD Miller]

Google:

"Bearing D.A.B. 86 8201 CAP L 3-39 A 4-39 DA 49" refers to a specific engine bearing, likely a "main bearing cap" for a particular engine model, where:

• D.A.B. 86 8201:
  This is the part number for the bearing, identifying it within the manufacturer's catalog.
• CAP L:
  Indicates that this is a "cap" bearing, meaning it's the top half of the bearing that secures onto the engine block.
• 
  
• 3-39 A 4-39 DA 49:
  These are likely dimensional codes related to the bearing's size and specifications, such as its diameter and width.

Key points about this bearing:

• Location:
  This bearing is most likely a main bearing cap, located on the crankshaft of an engine.
• 
  
• Function:
  The cap holds the lower half of the main bearing in place, allowing the crankshaft to rotate smoothly within the engine block.
  
  
• 
  
• Identifying the engine:
  To accurately determine which engine this bearing fits, you would need to cross-reference the part number "D.A.B. 86 8201" with the manufacturer's parts catalog.

Got calipers?

 

[KeyBlazer]

Yes.
I have Google as well...

I have a big array of measuring tools, as Ive rebuilt motors and done machining before.
Can measure the crank rod journals, in place, but not the mains.
Have Micrometers, bore gauges etc, but no ball end micrometers, but Im sure I can improvise to check the bearing shell thickness...
But I was hoping someone could decipher the DAB bearing stamps...

 

[Tonimus]

If they're not factory sized bearings, any reputable shop that oversized the rods/main caps or undersized the crank would have marked them as such. I would also think there'd be some sort of .010 or similar notation in the bearing.

 

[DoubleDingo]

Plastigage? I think all of those bearings can be measured with plastigage. I don't know, though, especially with it being oily.

 

[Ricko1966]

Platigage won't tell you if the bearings are standard .010 etc. It will tell you if clearances are correct. When you resize a rod or line hone a block we always took a tiny bit off the cap mating surface,now the bores are football shaped,then hone them out to standard round bore diamensions,never see or hear of anyone doing it other than back to std. O.D. you can measure your rod journals,as you already stated,if the rods are standard I would bet you money, the mains are standard. If you by new bearings buy 1 standard main shell,compare the thickness at the side of the shell not center of the shell with your old shell. Then it becomes a math problem. Post back if you need help. As for those stamping I have no clue,sorry. Use your micrometers,not calipers.

 

[KeyBlazer]

Thanks, I was unable to de cypher the bearing info...
Weird, that something like that is not out there...
Let me get after it, will report back.

 

[Camar068]

one down....349 questions to go

couldn't resist.

 

[KeyBlazer]

Hours of searching on these DAB bearings markings, and no joy.

Rod.

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Main.

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But needed to know what size this crank is...
So I went back to basics.

Research says stock Chevy Small block crank should have:
2.45" Main journals.
2.10" Rod journals.

The Main bearing "Tunnel size" in the block minus bearings should be 2.6410".....
I'm reading tolerance is 2.6405 to 2.6415, but lets stick to raw spec size of 2.6410".

So, using simple math.
Block bore should be 2.6410"
Crank main bearing should be 2.450
Difference is 0.16", divided by 2 for both sides of the bearing = 0.080"?
I pulled the main bearing out and measured it with some digital calipers... = 0.100
So my crank main journal is ground 10 under?

Stock Rod journal should be 2.10" diameter.
Stock Big end rod bore should be 2.2250
Difference + 0.125" Divided by 2 + 0.0625"

My rod bearing thickness is about 0.0635"
So also 10 under, I think!

So, if I get some new 10 under bearings, I could slap those in and if the Plastigauge says the clearances are good, its good to go!

 

[Craig Nedrow]

With the pan off like you have it, position any easier to get to rod at 90 degrees, unbolt cap and pull it off. install 3/8 hose on rod bolts if rods are stock, and turn crank another 90*, now you can measure. You will need help probably with reinstalling the rod back on the crank. However in theory, your above method should work. No ball mic? use a .25 ball bearing stuck onto your mic with a little stiff grease, (wheelbearing,) measure and -.250 for your reading. Your mind is working right.

 

[KeyBlazer]

Pic of where I am currently...

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And the Weiend pan im putting on...
Test fit says it works..

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I ordered a set of KING OEM spec mains and rods in 10 under, a new Plasigauge set, and a new rear main seal.
They will be here next week.