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Flywheel 101....

Discussion in 'The Garage' started by Zeus33rd, Mar 29, 2005.

  1. Zeus33rd

    Zeus33rd Smarter than you GMOTM Winner

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    Last night I learned that a flywheel from an older small block won't fit one of the new GM Goodwrench smallblocks with the 1 piece rear main seal. The mounting bolt pattern is smaller on the new stuff. Had to go to every parts place in town to find one. And of course, none of them wanted to look in the books....so I had to play the guessing game with different applications till we got one that worked. '89 K1500 was the right one. $35 flywheel....$110 core.... :yikes:
     
  2. 4X4HIGH

    4X4HIGH 1 ton status Premium Member GMOTM Winner

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    Joe, i could have told you that. Also if you look at the flywheel you will find that it is externally balanced like 400 SBC's but the later engines were only external on the rear not the front.
     
  3. CyberSniper

    CyberSniper 1/2 ton status Premium Member

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    I bought a flywheel for an 87 V20 for $75... no core... brand spanking new.
     
  4. Zeus33rd

    Zeus33rd Smarter than you GMOTM Winner

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    I actually thought about callin ya from Napa...But my cell phone with your # in it was at home. :screwy: And it's too late to look at the flywheel...It's already in the truck. :)

    Where at?

    Got mine at Kragen...I didn't have to pay the core charge, just gave them the old flywheel for the core. I couldn't use it anyways. So I still paid less than you. :p: :)
     
  5. Poohbair

    Poohbair 1/2 ton status

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    I **think** I may be in a similiar situation... I have the old style flywheel out of my rig, but I am going to get a diff motor on Saturday... it is a TBI 350 out of an 87. 1 person told me that all of the TBI motors used the 1 piece rear main and that I would need a diff flywheel... somebody else told me that they didn't change until 88 or 89 and that I would be good w/ my old one.. Does anyone know what year they actually changed from a 2 piece to a 1 piece rear main???
     
  6. tRustyK5

    tRustyK5 Big meanie Staff Member Super Moderator GMOTM Winner Author

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    Pre -87 is the two piece seal, 87 and newer is the one piece seal (and center bolt valve covers)

    Rene
     
  7. CyberSniper

    CyberSniper 1/2 ton status Premium Member

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    At Advance Auto. It was MotorMite 04623 (GM 10105832). One piece rear. Pretty much all 1986 blocks got center bolt valvecovers if not one piece rear main seals also... never seen an 87 that wasn't both one piece and center bolt. So, 87 is a safe year to guess.

    I didn't have any flywheels for cores... I almost bought the B&M flywheel for $10 more but they didn't have it in stock.
     
  8. beater_k20

    beater_k20 Banned

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    incorrect. pre 86 engines are 2pc RMS, 86+ got 1pc RMS. 87+ got centerbolt valve covers, along with 72* center mounting holes for the intake manifold.
     
  9. CyberSniper

    CyberSniper 1/2 ton status Premium Member

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    My 1986 K10 with a 305 has centerbolt valvecovers and a two piece rear main seal. My 1987 C10 has a one piece rear main seal and centerbolt valvecovers. My Mom's 86 Monte Carlo SS has a one piece rear main seal and centerbolt valvecovers.

    So, you aught to go back in time and tell GM to follow your instructions.
     
  10. diesel4me

    diesel4me 1 ton status Premium Member

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    86 a strange year...

    The 86 305 I put in my truck from an 86 G10 van had a one peice rear main,but has the "old" style valve covers!,and a cast iron Q-jet manifold..--I had to use the flywheel it came with,but I cant recall if it had any counterweights--I dont think it did...guess it was a wierd year for 305's... :confused:
     
  11. beater_k20

    beater_k20 Banned

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    GM did "follow my instructions" on every known 100% stock car i've ever seen, as well as the parts catalogs. maybe you should go back and tell your POs not to mess with cars and put non-stock parts on them.
     
  12. CyberSniper

    CyberSniper 1/2 ton status Premium Member

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    The 87C10 is stock down to the original spark plugs and wires. If you want to see them I pulled them out last Sunday.

    The 86 Monte Carlo SS my Dad ordered from a GM dealership with such oddities as power windows but manual locks and a bench seat and was never driven nor worked on by anyone else.

    The 86K10... who knows. The motor appeared to be bone stock and matched the drivetrain and all the emissions/sensors for the year so I assume it was stock. It didn't match the cab though (somebody transfered the dash metal to a 73-80 cab).

    Back to your regularly programmed "beater_k20 needs to join the band" broadcast.
     
  13. beater_k20

    beater_k20 Banned

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    the 87 C10 is 100% correct with centerbolt valve covers and a 1pc RMS

    there's a chance the 86 Monte SS could have been an early 86, and they were just using leftover 85 LG4s, which explains the 2pc RMS, or it could have been an early 87, early enough to still be titled an 86, which would explain the centerbolts. nothing that would explain both not being consistent for that model year. perhaps when the car was new, it was scabbed for parts temporarily to make a sale, then in order to complete the car the "incorrect" parts were installed. i have seen it happen on several occasions.

    you're not sure about your K10, and as we all know, a 1pc RMS block, and 2pc RMS block share the same external dimensions. so that point is pretty much worthless.

    as for joining the band, i see no reason for it. i'm just stating the facts, straight from several aftermarket parts supplier catalogs (Fel Pro, Victor-Reinz), GM parts catalogs, GMSPO and Partech, and my personal experiences over the last 15 years.
     

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