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Stupid, ignorant, dumb question about stock 350.

Discussion in '1969-1972 K5 Blazer | Truck | Suburban' started by BLAZEN70, Apr 25, 2003.

  1. BLAZEN70

    BLAZEN70 Registered Member

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    I'm thinking about buying a used 350 to rebuild in the garage at my own pace, so i can still drive my rig in the meantime. Now heres my dumb question,s. I have a stock 350 in my 70 blazer, does it have a 2 bolt or 4 bolt main? Does it matter?, and whats the difference? Is there anyway you can tell without taking the oil pan off and actually looking? /forums/images/graemlins/confused.gifPlease educate me. Thanks.
     
  2. Stroked72Blazer

    Stroked72Blazer 1/2 ton status

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    get the casting # and check it with www.mortec.com

    Unless you plan to do some high reving or build seriouse power (550+hp) then a 4 bolt is way over rated in my opinoin.
     
  3. Topdown

    Topdown 1/2 ton status

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    unless you are planning on 600hp, it doesnt matter if its 2 or 4 bolt.

    If you are going to run 600+ hp, you want a 2-bolt and "convert" it with splayed bolts to a 4-bolt. much stronger...

    -Ryan /forums/images/graemlins/k5.gif
     
  4. 72beater

    72beater 1/2 ton status

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    might as well get a 400, right?
     
  5. Blazer1970

    Blazer1970 1/2 ton status

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    If you have the stock engine from your '70, it is a 4 bolt main. All of the truck 350s of this era were 4 bolts.
     
  6. chevyracing

    chevyracing 1/2 ton status

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    if the casting number on the back of the block ends in 010 it is more than likely a 4 bolt, there are a few exceptions though. Here are all of the small block casting numbers

    SBC BLOCKS


    CASTING#.....SIZE...YEAR...MAIN CAP BOLTS....NOTES

    140029.....350...80-84...2
    330817.....400...72-80...2
    355909.....262.....75....2
    355909.....305...76-79...2
    360851.....262...75-76...2...Monza V-8
    361979.....305...77-79...2 or 4, some Canadian assembled heavy duty blocks have 4-bolt main caps
    366245.....350...78-79...2
    366286...................4...Bowtie, Aluminum, siamesed,
    straight nodular iron main
    caps, 2-piece seal, 4.00-4.150"
    bores, 2.45" main journals
    366287...................4...Bowtie, Aluminum, siamesed,
    straight nodular iron main
    caps, 2-piece seal, 4.00-4.150"
    bores, 2.45" main journals
    366299...................4...Bowtie, Aluminum, nodular
    iron splayed caps, wet sump,
    4.00" bore
    389257.....302.....67....2
    393288.....283...65-67...2
    460703.....350.....78....4
    460776.....305...78-79...2
    460777.....305...78-79...2
    460778.....305...78-79...2 or 4, some Canadian assembled heavy duty truck blocks have 4-bolt main caps
    471511.....267...79-82...2
    3556519....283...58-61...2
    3703524....265.....55....2...No oil filter
    3720991....265...56-57...2
    3731548....265...57......2...No side motor mounts
    3731548....283...57......2...No side motor mounts
    3737739....283...58-64...2
    3756519....283...58-62...2
    3782870....327...62-67...2
    3789817....283...62-64...2
    3789817....327...62-67...2
    3789935....283...61-64...2
    3790721....283...62-64...2...Chevy II recessed oil filter boss
    3790721....327...65-66...2...Chevy II recessed oil filter boss
    3791362....327...62-67...2...Chevy II recessed oil filter boss
    3792563....327.....65....2
    3792582....283...64-65...2
    3794226....283...58-63...2
    3794460....327...62-64...2
    3814660....327...68-69...2
    3830944....327.....63....2
    3834810....283...64-66...2
    3834812....283...62-63...2
    3837739....283...58-62...2
    3849852....283...57-66...2
    3849935....283...65-67...2
    3858174....327...64-67...2
    3858180....327...64-67...2
    3858618....350...68-76...2
    3862194....283...65-67...2...Chevy II recessed oil filter boss
    3862812....283...62-64...2
    3892657....302.....67....2...Z-28 Camaro
    3892657....327.....67....2
    3892657....350.....67....2...Camaro
    3896944....283...66-67...2
    3896948....283...66-67...2
    3903352....327.....67....2
    3914636....307.....68....2
    3914638....327.....68....2...Truck
    3914653....307...68-73...2
    3914660....327.....68....2
    3914678....302.....68....2...Z-28 Camaro
    3914678....327.....68....2
    3914678....350.....68....2
    3931174....307.....68....2...Truck
    3932371....307...69-73...2
    3932373....307...68-73...2
    3932386....302.....69....4...Z-28 Camaro
    3932386....327.....69....2
    3932386....350.....69....4
    3932388....350.....69....2 or 4
    3933180....327...68-69...2
    3951509....400...70-71...4
    3951509....400...74-80...2
    3951511....400...70-73...4...Some replacement blocks had 2-bolt main caps
    3956618....302.....69....4...Z-28 Camaro
    3956618....327...68-69...2
    3956618....350.....69....2 or 4
    3956632....307.....69....2
    3959512....327...62-67...2...Was also used for some replacement blocks
    3970010....302.....69....4...Z-28 Camaro
    3970010....327.....69....2...Trucks and industrial
    3970010....350...69-80...2 or 4
    3970014....350...70-76...2 or 4
    3970020....307...70-73...2
    3970024....307...69-73...2
    4715111....305.....80....2
    6259425....350...69-76...2
    10036033...350...........4...Goodwrench crate motor, 2-piece rear
    seal, "Hecho en Mexico"
    10051182.................2 or 4...Bowtie, 3.75"-4.30" bores, 1 or 2-piece rear seal
    10051184.................4...Bowtie, 4.00"-4.155" bores, 1 or 2-piece rear seal
    10054727...350...86-up...2 or 4...one piece rear seal, some "Made in Canada"
    10066036...350...........2 or 4...Target Master/Goodwrench crate motor, 2-piece rear
    seal, "Hecho en Mexico"
    10066038...350.....92....4...Goodwrench crate motor, 2-piece rear
    seal, "Hecho en Mexico"
    10090511...350.....90....2...LT-5, ZR1 Vette, 375hp
    10125327...350...92-up...2 or 4...Gen.II LT-1, reverse flow cooling
    10125327...350...96-up...2 or 4...Gen.II LT-4, reverse flow cooling
    10134996.................4...Bowtie, Aluminum, 4.125" bore
    2.65" main journals
    10153558...350...91-92...4...LT-5, ZR1 Vette, 375hp
    10168588...265...94-96...2...L99, Gen.II, 4.3 Liter V-8, Caprice, reverse flow cooling
    10199001...350...93-95...4...LT-5, ZR1 Vette, 405hp
    10243878...305...96-98...2...Vortec truck, roller cam, one-piece rear seal
    10243880...350...95-00...2 or 4...Vortec truck, Gen.I crate motors and "ZZ4", roller cam, one piece rear seal
    12550592...350...97-up...crossbolted block, Gen.III, "LS1", aluminum
    12559378...350...99-up...crossbolted block, Gen.III, "LS1", aluminum
    12559846...350...98-up...crossbolted block, Gen.III, "LS1", aluminum
    12560621...350...98-up...crossbolted block, Gen.III, "LS1", aluminum
    12560629...350...99......crossbolted block, Gen.III, "LS1", aluminum
    12561168...350...01-up...crossbolted block, Gen.III, "LS1", aluminum
    12562174...350...98-up...crossbolted block, Gen.III, "LS1", aluminum
    14010201...305...80-85...2
    14010202...305...80-85...2
    14010203...305...80-85...2
    14010207...350...80-85...2 or 4
    14010209...350...80-85...2 or 4
    14010280...267...79-82...2
    14011064...350...83......4
    14011148...350...87-89.......Roller cam, one-piece rear seal
    14016376...267...79-82...2
    14016379...350...77-79...2 or 4
    14016381...305...80-84...2
    14016382...305...79-84...2
    14016383...305...80-85...2...Truck
    14079287...350...86-90.......Truck
    14088526...350...87-89.......Roller cam, one-piece rear seal
    14088548...350...86-88...2 or 4
    14088551...305...86-87...2...one-piece rear main seal
    14093627...305...87-91...2...Roller cam, one-piece rear seal
    14093638...350...87-95...2 or 4...Roller or flat tappet cam
    one-piece rear seal
    14094766...305...86-up...2...One-piece rear seal
    14101147...305...85-up...2
    14101148...350...87-90...4...One-piece rear seal
    14102058...305...87-91...2...Roller cam, one-piece rear seal
    22551656.................4...Rocket block, 4.00"-4.190" bores, 2.45" main
    journal sizes, splayed caps, dry sump,
    2-piece rear seal, 9.025" deck



    John
     
  7. BLAZEN70

    BLAZEN70 Registered Member

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    Thanks for all the input guys! I now know alot more than i did before. /forums/images/graemlins/thumb.gif
     
  8. '72brett

    '72brett 1/2 ton status

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    the 4-bolt main was created for taking up the shock of extra torque created by a truck engine. a 2-bolt main will work fine because the T-case takes up the "shock" and does a good job at it too. FOr other people that wanted it, I have replaced a blown engine with a 2-bolt main. but I have never done it in any of my own, I like the sense of security provided by a 4-bolt. Some place I heard that with a 400cid a 2-bolt hold up better than a 4-bolt. Not sure on that, but it is what I heard.
     

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