rotating assembly bearings

Discussion in 'Rotating Assemblies' started by elisalvador, Aug 6, 2013.

  1. elisalvador

    elisalvador Member

    hi grumpy had a question , im rebuilding a 350 chevy. the crank readings are main bearing journal is 2.448 and rod journals read 2.098
    so does this mean that I would need standard sized bearings? and also when installing new bearing from the box , do I need to clean them and if so with what ?
    thanks
     
  2. grumpyvette

    grumpyvette Administrator Staff Member

    http://www.mortec.com/journal.htm

    Gen.I, "Medium Journal", includes "Vortec" 305 and 350 thru '98
    262...Mains-2.45"-Rods-2.10"
    267...Mains-2.45"-Rods-2.10"
    302...Mains-2.45"-Rods-2.10"
    305...Mains-2.45"-Rods-2.10"
    307...Mains-2.45"-Rods-2.10"
    327...Mains-2.45"-Rods-2.10"
    350...Mains-2.45"-Rods-2.10"
    Common assembly clearances
    you'll
    need accurate precision measuring tools

    http://garage.grumpysperformance.com/index.php?threads/precision-measuring-tools.1390/
    if your certain the bearing clearances measurements are correct, with the plasti-gauge used to verify, once the short block assembly is assembled.
    (and ID certainly take the measurement on bearing clearances,
    on all the main journals then rotate the crank about 120 degrees and do it again ,twice too be sure,)
    verify with plasti gauge you should be good to go,
    if those bearing clearances fall into the ranges stated below.


    they make bearing sets that are either .001 under and over sized as one option

    heres what Ive used for decades
    .

    Rod bearings 0.002 - 0.025" , side clearance 0.010 - 0.020"

    Main bearings 0.002 - 0.003" for most engines
    ( 0.020-0.025 bearing clearance on small blocks,
    .025-.027 bearing clearance is about ideal, on big blocks )
    , 0.005 - 0.007 crankshaft end play

    Piston to head clearance 0.038 MINIMUM including gasket
    (.038-.042 quench is what you want with steel rods)(steel rods),
    0.060" MINIMUM quench aluminum rods

    Valve to piston clearance MINIMUM 0.100" exhaust , 0.080" intake NO VALVE FLOAT
    Recommended: 0.080 intake, 0.100 Exhaust (steel rods) 0.100 intake, 0.120 Exhaust aluminum rods
    TORQUE SPECS CAN BE FOUND HERE IN THIS LINK


    http://garage.grumpysperformance.com/index.php?threads/torque-specs-calculator-links-etc.1222/

    http://garage.grumpysperformance.com/index.php?threads/bearing-clearances.2726/




    If the bearing clearances are a 1/4-1/2 thousandth (.ooo25 -.0005) or tiny bit more, more on the tighter side, you could manually polish the crank journals with a strip of 1500 grit wet/dry sand paper on a leather belt and easily get an extra .00005

    (surface wet with wd 40) but of course the local crank polishing service machine shop would do it more precisely and generally will cost under $100, to do that
    why not talk to a trusted local machine shop and ask their opinion and for suggestions



    (ALWAYS consult your piston manufacturer for recommended clearances. Many pistons require a tighter bore)

    Piston to bore 0.0055 - 0.0065" ( measured at centerline of wrist pin, perpendicular to pin)


    Piston ring gap MINIMUM end clearances Top 0.022"
    2nd 0.016"
    Oil 0.016"

    Wrist pin 0.0006 - 0.0008" in piston, 0.0008 - 0.0010" in rod for full floating pin (End play 0.0 - 0.005"

    Rod bearings 0.002 - 0.025" ,
    side clearance ...... 0.010 - 0.020"

    Main bearings 0.002 - 0.003" ,
    crankshaft end play...... 0.005 - 0.007


    Piston to head clearance 0.035 MINIMUM including gasket (steel rods), 0.060" MINIMUM aluminum rods

    Valve to piston clearance MINIMUM 0.020" exhaust , 0.010" intake NO VALVE FLOAT
    Recommended: 0.080 intake, 0.100 Exhaust (steel rods) 0.100 intake, 0.120 Exhaust aluminum rods
    obviously youll want to check clearances with plasti gauge once the bearings are available also (READ THE LINKS) and use assembly lube on the bearing surfaces during assembly, you can clean them out of the box with a lint free cloth and a bit of diesel fuel then install them, check clearances , and use assembly lube before final assembly but it looks like youll have clearance in the correct range if you get the correct bearings
    [​IMG]
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    VERIFYING CLEARANCES GREATLY REDUCES WEAR AND DURABILITY ISSUES

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    http://www.engineprofessional.com/TB/EPQ410_10-18.pdf
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    http://www.tooltopia.com/fowler-72-646-300.aspx








    [​IMG]


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    The Moly platelets that make up the protective layers on your engine surfaces slide across one another very easily. Instead of metal rubbing against metal, you have Moly platelets moving across one another protecting and lubricating the metal engine parts.
    [​IMG]
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    MOLY adds a great deal of lubrication to sliding metal surfaces , as it embeds in the micro fissures in the metallic surface's
    [​IMG]


    This coating effectively fills in the microscopic pores that cover the surface of all engine parts, making them smoother. This feature is important in providing an effective seal on the combustion chamber. By filling in the craters and pores Moly improves this seal allowing for more efficient combustion and engine performance.
    [​IMG]
    This overlapping coating of Moly also gives protection against loading (perpendicular) forces. These forces occur on the bearings, and lifters. The high pressures that occur between these moving parts tend to squeeze normal lubricants out.

    reading these threads, and sub linked info, will provide a great deal of additional info, youll want later

    viewtopic.php?f=69&t=3814

    viewtopic.php?f=53&t=5478&p=16429&hilit=feed+journal#p16429

    viewtopic.php?f=50&t=1222

    viewtopic.php?f=53&t=4419&p=11688&hilit=feed+journal#p11688

    viewtopic.php?f=53&t=852&p=21611&hilit=plasti+gauge#p21611

    viewtopic.php?f=53&t=509

    viewtopic.php?f=53&t=2726

    viewtopic.php?f=53&t=247

    viewtopic.php?f=53&t=619&p=16819&hilit=causes+bearing+failure#p16819

    viewtopic.php?f=53&t=4630

    http://www.stealth316.com/misc/clevite- ... ooving.pdf

    http://stealth316.com/misc/clevite-77-r ... arings.pdf

    http://kingbearings.com/files/Engine_Be ... erials.pdf

    [​IMG]

    you might keep in mind bearing manufacturers are in business to sell bearings and if a small but consistent segment insists on buying and paying for 270 and 360 degree bearings the manufacturers will supply that demand to make a profit, they will also post tech bulletins explaining why a 180- degree oil feed groove in only the upper bearing shell provides a more durable bearing that carries more load capacity

    heres a quote from a bearing manufacturer

    extending the main bearing groove much past 180 degrees increases friction, reduces load capacity costing hp, read the link
    "Influence of Grooving on Main Bearing Performance
    Various forms of main bearing grooving have been used over the years. We are
    frequently asked what difference grooving makes.
    First, it’s essential to understand that bearings depend on a film of oil to keep them
    separated from the shaft surface. This oil film is developed by shaft rotation. As the shaft
    rotates it pulls oil into the loaded area of the bearing and rides up on this film much like a
    tire hydroplaning on wet pavement. Grooving in a bearing acts like tread in a tire to break
    up the oil film. While you want your tires to grip the road, you don’t want your bearings
    to grip the shaft.
    The primary reason for having any grooving in a main bearing is to provide oil to the
    connecting rods. Without rod bearings to feed, a simple oil hole would be sufficient to
    lubricate a main bearing. Many early engines used full grooved bearings and some even
    used multiple grooves. As engine and bearing technology developed, bearing grooving
    was removed from modern lower main bearings. The result is in a thicker film of oil for
    the shaft to ride on. This provides a greater safety margin and improved bearing life.
    Upper main shells, which see lower loads than the lowers, have retained a groove to
    supply the connecting rods with oil.
    In an effort to develop the best possible main bearing designs for High Performance
    engines, we’ve investigated the effects of main bearing grooving on bearing performance.
    The graphs on the next page illustrate that a simple 180° groove in the upper main shell is
    still the best overall design.
    While a slightly shorter groove of 140° provides a marginal gain, most of the benefit is to
    the upper shell, which doesn’t need improvement. On the other hand, extending the
    groove into the lower half, even as little as 20° at each parting line (220° in total), takes
    away from upper bearing performance without providing any benefit to the lower half.
    It’s also interesting to note that as groove length increases so do Horsepower Loss and
    Peak Oil Film Pressure which is transmitted directly to the bearing."
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    Last edited by a moderator: Jul 31, 2017
  3. elisalvador

    elisalvador Member

    thanks grumpy....can I ask a question why do they call you grumpy?
     
  4. grumpyvette

    grumpyvette Administrator Staff Member

    It was a "TERM my WIFE had used in referring to me ,for DECADES that my FRIENDS PICKED UP ON"

    typically a phone call from my friends would go like ......
    WIFE......... HELLO?
    CALLER......Is PAUL around?
    WIFE.........I THINK THE OLD GRUMPY GUYS OUT UNDER A CAR < ILL CHECK!
    pause
    WIFE.........yeah GRUMPYS COMING
    PAUSE..


    AFTER A FEW MONTHS
    WIFE......... HELLO?
    CALLER......Is GRUMPY around?
    WIFE.........I THINK THE OLD GRUMPY GUYS OUT UNDER A CAR < ILL CHECK!
    pause
    WIFE.........yeah GRUMPYS COMING
    PAUSE..
     
  5. Grumpy

    Grumpy The Grumpy Grease Monkey Staff Member

    http://www.hotrod.com/articles/select-install-high-performance-engine-bearings/
    shop carefully the exact same set of mics from the same company can cost $270-$900 depending on where you buy the set
    https://www.greatgages.com/products...MIyYigxdnA1QIVU2p-Ch1Z7wX8EAQYASABEgLrvvD_BwE


    don,t assume the bearing journal diameters are correct, on any crankshaft,
    , ( while they are almost certainly correct on a SCAT crank)
    its good practice and certainly smart to measure carefully to be 100% sure, and that youve purchased and matched them to the correct matched bearing set!
    [​IMG]

    btw I got asked how I apply the 50%/50%
    mix of MARVEL MYSTERY OIL AND CRANE MOLY ASSEMBLY LUBE TO BEARINGS
    I generally spray crank journals and bearing surfaces with moly spray first , then paint on the mix linked below.
    [​IMG]


    Preference on assembly lube?

    50% marvel mystery oil
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    and 50% crane moly lubes
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    what Ive used for decades
    but this works

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    I have used J&B WELD EPOXY on a large magnet
    https://www.zoro.com/value-brand-ring-magnet-98-lb-pull-10e797/i/G4187224/


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    on the base of an aluminum 1/2 cup measuring cup I purchased at a yard sale for 25 cents to mix up the mixture, the magnet allows me to stick the cup to the block oil pan rail or engine stand where its handy too get at, and I simply brush on the mix with a 1" paint brush, with synthetic bristles that won,t shed
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    OH!
    slide it off the block don,t try to just pull it off , its going to be much less messy that way trust me!
    when your done , wipe it clean and stick it inside the lid of your tool box , after placing it in a ziploc bag to prevent it from picking up trash while in storage



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    Last edited: Aug 19, 2017 at 4:46 PM

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