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Can you build a real Chevy 302?

Discussion in 'The Hokey Ass Message Board' started by Lucky Strike, Sep 27, 2005.

  1. Wont post the link as its not a hamb friendly car but on Youtube, search for Ben Wenzel Z/28. Guy is the original owner of a 67 Z/28 and has been racing it since new, currently in C/Stock. There is a in car video and if you can watch on HD on a larger screen you can clearly see the tach needle. Dumps the clutch at 6200rpm and the power shifts it at near 10k rpm. Those little 302s are just nuts.
     
  2. Roothawg
    Joined: Mar 14, 2001
    Posts: 24,522

    Roothawg
    Member

    There used to be a guy around here that spent tons of money on his 301 valve train to get it to wind tight. It wasn’t efficient, because it was flat once it nosed over, but he liked people to hear it. It was fun to watch.
     
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  3. Brian Penrod
    Joined: Apr 19, 2016
    Posts: 216

    Brian Penrod
    Member

    That a cool story on Ben and his brother and the 67 Z28.
     
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  4. irunonbeer
    Joined: Feb 1, 2018
    Posts: 11

    irunonbeer

    I am looking at a set of .060 over 302 pistons and 2 have scuffing on the sides. What would cause that ? Are they still good to use? Thank you B5DAA32A-6A2C-47A9-8FC3-3865E41E56B6.png
     
  5. GlassThamesDoug
    Joined: May 25, 2008
    Posts: 1,527

    GlassThamesDoug
    ALLIANCE MEMBER

    Dont like that, either lube issue, as in insufficient film, or tight. Over heat is usually more of a 4 corner scuff due to material around pin boss. Either way, their ash trays, Wisceo, SRP, JE make new pistons, go that route. Spend money in Pistons, will pay off.
     
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  6. GlassThamesDoug
    Joined: May 25, 2008
    Posts: 1,527

    GlassThamesDoug
    ALLIANCE MEMBER

    forum-25.jpg
    Put this one together in July 2021. Nice street driver.
     
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  7. irunonbeer
    Joined: Feb 1, 2018
    Posts: 11

    irunonbeer

    Thank you, kinda what I was thinking! Have a great day!
     
  8. GlassThamesDoug
    Joined: May 25, 2008
    Posts: 1,527

    GlassThamesDoug
    ALLIANCE MEMBER

    I bought a digital scale to check piston weights, so I dont have to rebalance crank. 70s TRW 302/327 12:1 are 715g, JE 406 14:1 are 595g. Other advantages can be found.
     
  9. Tickety Boo
    Joined: Feb 2, 2015
    Posts: 1,610

    Tickety Boo
    Member
    from Wisconsin

    Any one know the weight of a stock 283 piston to compair to the others :rolleyes:
     
  10. GlassThamesDoug
    Joined: May 25, 2008
    Posts: 1,527

    GlassThamesDoug
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    I checked 16 LJ 350 rods, Xs and Ks all were same weight, one was 5g off. I wonder how close factory parts were. Someone working there would know.
     
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  11. Fordors
    Joined: Sep 22, 2016
    Posts: 5,372

    Fordors
    Member

    575.5 grams without the pin.
     
  12. CNC-Dude
    Joined: Nov 23, 2007
    Posts: 1,031

    CNC-Dude
    Member

    If there is that much weigh difference between the pistons you certainly will have to rebalance the crank....
     
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  13. CNC-Dude
    Joined: Nov 23, 2007
    Posts: 1,031

    CNC-Dude
    Member

    Well it depends on how close the rod weights on the X rods are compared to the original rods the crank was balanced to. 5g's between the whole set is closer than what a factory matched set usually is, but if they are 30 or 40g heavier or lighter than the original set you'll have to rebalance the assembly....
     
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  14. brigrat
    Joined: Nov 9, 2007
    Posts: 5,615

    brigrat
    Member
    from Wa.St.

    Out of balance "is" out of balance, your RPM destination will determine how finicky you wanna get on the balancing.........
     
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  15. GlassThamesDoug
    Joined: May 25, 2008
    Posts: 1,527

    GlassThamesDoug
    ALLIANCE MEMBER

    Digital scales at Harbor Freight... works for me $39. I checked 70s era 17 TRW 12:1 pistons...302s and 327s... same wt.. with pins. Interesting.
     
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  16. Tickety Boo
    Joined: Feb 2, 2015
    Posts: 1,610

    Tickety Boo
    Member
    from Wisconsin

    Closest weight I found so far was the Icon hollow dome 302 piston #IC802 at 552 grams without the pin.
    The pin is 132 grams, some things can be done to get close like using thicker wall piston pins. ;)

    A engine builder/engineer ( he shall remain anonymous ) told me that if you are starting out with a balanced assembly and are only changing pistons/pins and remain within + or -2% of the current piston/pin you will be OK. o_O
    He went on to say that the balancing guys will tell you everything needs to be with in 1/4 gram, but if they told you the truth they would starve :eek:

    I ended up about 6 grams lighter ( 548 grams to 542 ) on my last piston/pin change on a big inch smll block Chevy
    with no ill effects ;)
     

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  17. CNC-Dude
    Joined: Nov 23, 2007
    Posts: 1,031

    CNC-Dude
    Member

    It's common for race engines to be over balanced by 1-1/2 to 2%. But yeah, trying to weigh components to within 1/4g is simply marketing baloney. Plus or minus 5 or 6 grams you'd never know it.
     
  18. buick bill
    Joined: Dec 18, 2008
    Posts: 856

    buick bill
    Member
    from yreka;ca

    well someone woke the dead here . been reading it for hours . almost forgot where it all started !! anyway . kinda on topic . seems like i read that gm made the 305 because it was the best all around compromise for bore x stroke.how does that compare to a 302 ? built the same wouldnt they have close to the same hp/ torque / rpm .?ive got a 283 and a 305 horded in one of my garages . is it stupid not to scrap them both . seems in the day of 454 sbc of the shelf , none of it makes much sense ! or is that ot ? i did have a built 283 in my old malibu with a muncie behind it . may not have really been fast . but , sure was fun to hit second in . and with the posi it kept you on your toes !..sure seemed fast 1965 malibu 007.jpg 1965 malibu 017.jpg 1965 malibu 013.jpg
     
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  19. i7083
    Joined: Jan 3, 2021
    Posts: 165

    i7083
    ALLIANCE MEMBER

    The motor that was in my coupe when we dug it out of the field is a '69 302 block. It appears to have a 350 crank in it. Haven't taken it apart yet...
     
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  20. Budget36
    Joined: Nov 29, 2014
    Posts: 13,173

    Budget36
    Member

    Regarding the 305 and 302, although displacement is close, two things are different. Bore on the 302 is 4 inch, stroke is 3.25. The 305 is somewhat opposite, 3.48 stroke, 3.78? Bore.
    The 302 allows the bigger valves but the 305 shrouds them. It’s possible that bores are in the way of the valve, but no experience to say one way or the other.
     
  21. Didn't they just use a 350 4 bolt for the 68 and 69 302? JW
     
  22. The 302 has a 3'' stroke not 3.25'', thats a 327-307 stroke. JW
     
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  23. Budget36
    Joined: Nov 29, 2014
    Posts: 13,173

    Budget36
    Member

    Good catch. I’m aging and forget;)
     
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  24. Deuces
    Joined: Nov 3, 2009
    Posts: 23,752

    Deuces

    Why not use a small journal 327 block???....o_O:rolleyes::rolleyes::rolleyes:
     
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  25. Fordors
    Joined: Sep 22, 2016
    Posts: 5,372

    Fordors
    Member

    HTF in my neck of the woods, can you find SJ blocks easily in Michigan?
     
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  26. GlassThamesDoug
    Joined: May 25, 2008
    Posts: 1,527

    GlassThamesDoug
    ALLIANCE MEMBER

    My LJ 302 is ready to build, think I'll swap out pink rods & TRW pistons for stronger and lighter modern components. Rebalance and roll... Like to go flat top with smaller cc heads.
     
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  27. Going back to the original question,''Can you build a real 302''.. i take it as can you build one with exact parts as used from 67,8,9. Block, heads, crank and rods, intake, in other words ''make an exact copy at the least. JW
     
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  28. GlassThamesDoug
    Joined: May 25, 2008
    Posts: 1,527

    GlassThamesDoug
    ALLIANCE MEMBER

    I got several 327 sj blocks... for sale.... I have another 302 sj spare crank too.. if your looking. My LJ 302 block and crank can go for what I got in them....making room in Ohio...
     
  29. GlassThamesDoug
    Joined: May 25, 2008
    Posts: 1,527

    GlassThamesDoug
    ALLIANCE MEMBER

    Typical heads that can be used on a 302, 462 camel humps... donated to my buddy cuz his kids are building a sbc gasser.. teaching them how to build their first engines tomorrow. 20211218_145148.jpg
     
    Last edited: Dec 19, 2021
  30. GlassThamesDoug
    Joined: May 25, 2008
    Posts: 1,527

    GlassThamesDoug
    ALLIANCE MEMBER

    Yes 302 sj cranks were used in some HD 283 applications. How to tell is they have single notch in round flange. 5.7 sj rods can be pink or green code, green (floated) is more rare. The 327 blocks were same 2bolt sj castings used for 302. LJ castings are easy to locate, LJ cranks are available all the time on EBAY. Fundamentally a 3in stroke, 5.7 pink con rods, 4in bore is all it takes. TRW original design with GM part numbers are also available. All parts to build a component correct 302 are available ... its how much you want to spend. Cylinder heads are everywhere...no longer special, 462, 492, 291, 041, 040, 186, ..... MORTEC will give you casting, forging numbers that can be used for 302s. Camaro oil pans, windage trays and studs were available from GM 10yr ago, original intakes and correct carbs are available as well. Cams with correct grinds are available by at least 10 different cam grinders. This should answer.... YES its not difficult.
     
    Last edited: Dec 27, 2021

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