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302 SBC questions

Discussion in 'The Garage' started by big_truxx, Jan 28, 2005.

  1. big_truxx

    big_truxx 1/2 ton status

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    I know the old 302 SBC was a 4" bore with a 3" stroke. It was built with a 350 block wasn't it? Also where could I find a 3" stroke crank?
     
  2. diesel4me

    diesel4me 1 ton status Premium Member

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    maybe....

    The 302 they had in the 69 Z28 camaro's was a hybrid the made by using a 283 style 3 inch stroke crank in a 327 block(4 inch bore)..I dont recall all the specs,like if they were 4 bolt main motors or not--I know a few guys who "made" a 302 by putting a 307 crank in a 350 block(that makes the same stroke and bore as a302 had)--this way they could use a 4 bolt main block,but the crank was still a cast one though--you could put a 283 crank in a pre-67 327 block,but not the later 327's or 350's due to the smaller main bearing journals on the older motors.(I think the 302 had a unique crank all its own,with large journals and the short stroke)...the 302 was mainly a high RPM screamer with a hot cam and lots of top end power,but they were doggy until you wound them up,not much low end torque ..not a good truck or 4x4 motor,in my opinion...:crazy:
     
  3. 84_Chevy_K10

    84_Chevy_K10 Banned

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    327 and 350 = same block if both are large journal.

    A modern 1 piece rear main seal 302 could be built with a 350 block and a crank from a 262 V8.

    IMO, this stuff is outdated. 383s spin 6,500 RPM all day long. 350s 8000 plus. With modern balancing techniques, good connecting rods, bolts, and forged gear, short stroke motors are a thing of the past unless to try to get into a racing class by reducing CID. Why run 302 CID and spin it 8,000 RPM, when you can run 383 CID and spin it 6,500 or so and it'll make WAY more power?

    The original 302 Chevy, called a "301" by hot rodders of the day, was a 283 block bored to 4".
     
  4. sled_dog

    sled_dog 1 ton status

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    I want to build an aftermarket 400 block with a 3" stroke. 4.165 bore x 3" stroke = an even higher revving 327 ;). Yes I know modern balancing technology allows for better RPMs out of bigger motors but you still have Piston Speed and the less piston speed the high revs. I am pretty certain I will never do it cause I could build something better and more powerful for the same money. If I ever have a race shop maybe I will do it just to be different. The original 302s ate up the road racing circuit but didn't have a chance in the 1/4 mile.
     
  5. R72K5

    R72K5 Banned

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    350 327 and 302 are shared blocks, especially in 69
     
  6. big_truxx

    big_truxx 1/2 ton status

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    the 307 has a 3.250" stroke. That added to the 350 block would be the 327 ;) I found a cool info page; http://www.nastyz28.com/sbcmenu.htmlhas info on SBC engines. I would assume that the 302 used the standard 5.7" SBC con rod right?
     
  7. big83chevy4x4

    big83chevy4x4 3/4 ton status

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    the 302 was never made in 69, they stopped in 68 when they lifted the CID rule.

    the 302 was a road racing engine made to fit the rules at the time. 327 was too big and the 283 did not have enough power to make the racers happy, so they put a 283 crank in a 327 block and thus creating the 302. rated from the factory at 295 hp but were closer to 395 hp.
     
  8. R72K5

    R72K5 Banned

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  9. big_truxx

    big_truxx 1/2 ton status

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    I really don't know about high revving a longer stroked motor. I just feel that a short stroke is always better revved. :dunno: maybe just a matter of opinion. I'm just curious about 302's as they were less common than the other motors and not around anymore. Does anyone make a 3" stroke crank these days?
     
  10. big83chevy4x4

    big83chevy4x4 3/4 ton status

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    i have never seen one in a 69 only 67 and 68. but i wasn't around then, so what do i know. its just was i have been told and read
     
  11. ryoken

    ryoken Puppy Fabricator Premium Member GMOTM Winner

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    Scat has any stroke you can think of.... not sure about the others...
     
  12. NJBLZ

    NJBLZ 1/2 ton status

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    I like the 377. 400 bore- 4.126" x 350 stroke 3.48"

    I plan on having one built for my nova, with a dart little m block
     
  13. big_truxx

    big_truxx 1/2 ton status

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    I ran some #'s on the dyno and @ 6500rpm the 383 is past peak hp and has lost 80hp from its peak #. It peaked at 5,000. I don't know about a 350 @ 8,000... I guess maybe in a $10,000 crate it may still be making good power at that speed but for a home built on a budget type "normal" motor I do not see anything spinning 8 grand. I guess another thing I was thinking about is; doesn't rpm affect your speed anyway? Like wouldn't an engine that has 350 peak hp at 6,500 go faster than on that has 350 peak hp at 5,000?
     
  14. big_truxx

    big_truxx 1/2 ton status

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    That's actually a 372 CID. ;) 377 comes from 4" 350 and 3.750" stroke crank :D
     
  15. diesel4me

    diesel4me 1 ton status Premium Member

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    Yup!--I was wrong!!

    Yes,you are correct,it WAS a 283 crank in a 327 or 350 block that makes a 302--I was thinking of my friends "mongrel" motor he made out of spare parts,he used a 307 crank in a 350 block to make a 4 bolt main 327 cid motor--I guess my brain cant remember everything back that far,when I had hair,teeth,and better eyesight!:blush:

    But I'm 99% sure they had 302's in 69,my friends Z28 had one factory,he bought it brand new,still has it,only 34,000 miles on it now--its a convertible too!--he had it appraised,the guy said its worth 25.000 bucks minimum!:eek1: --now he's scared to take it out of the garage!:crazy:
     
  16. big_truxx

    big_truxx 1/2 ton status

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    They did have 302's in 69. Also how did they put the 283/265 3" stroke small journal in the large journal block? weld and machine the crank or what?
     
  17. chevy_muscle

    chevy_muscle 1/2 ton status

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    '69 Z28's had a 302 in 'em

    BTW, a short stroke allows a lower average piston speed at a given RPM. The realized limit of the rods/pistons/cranks is this "average piston speed". A longer stroke causes a higher average piston speed at a given RPM.

    You really need to "TUNE" your entire vehicle to determine what is the best combination. For example, you should consider weight, rearend ratio, transmission gearing, tire size and finally engine RPM band and to some extent aerodynamics(of the vehicle) that you plan to run in given driving conditions.

    when you figure all that out, you should know what kind of RPMs you need to run...... and then you can choose the right characteristics of the engine (like intake and exhaust flow, cam, compression, stroke, bore, etc..) for an amount of power you want.

    .... if you can't figure all that out... then remember the golden rule..... there's no (or few) replacements for displacement.
     
  18. pauly383

    pauly383 Daddy383 Staff Member Moderator

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    They used a large journal crank in 68 and 69 casting # 3279 , forged steel :k5: :k5:
     
  19. big_truxx

    big_truxx 1/2 ton status

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    :waytogo: :D
     
  20. pauly383

    pauly383 Daddy383 Staff Member Moderator

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    While displacement is great , every 100 pounds is worth a tenth of a second :D
     

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