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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. brigrat
    Joined: Nov 9, 2007
    Posts: 4,814

    brigrat
    ALLIANCE MEMBER
    from Wa.St.

    Well here's 5 pages of info, enough to make your head spin! Can someone just post the parts needed to make a 301 and a 302? I am not very good at puzzles and would like to see it in a more user friendly order before I throw out or give my SBC stash away. I to would like to build one of these....................
    Block?
    Crank?
    Rods?
    Pistons?
    Heads?
    Cams?
    Thanks.................................
     
  2. Shaggy
    Joined: Mar 6, 2003
    Posts: 5,208

    Shaggy
    Member
    from Sultan, WA

    Basicly without spending big bucks for a large journal z-28 crank here it is

    302 pistons
    283 crank with small journal rods
    4" bore small journal block, as in 1/8 over 283 or 327 OR 4" bore Large journal block (late 327 or 350)with spacer bearings

    All other parts are normal small block stuff
     
  3. Brad54
    Joined: Apr 15, 2004
    Posts: 6,006

    Brad54
    Member
    from Atl Ga

    Quality rods, rather than stockers. For the price of rebuilding stock rods and fitting them with ARP fasteners, for a little more you can get H-beams with ARP bolts already installed.

    Main studs are a good idea as well. No need for 4-bolt caps with a small-journal block, because small journal caps are pretty thick. As the main size increased later, they just took the material out of the caps, without adding material.

    I buzzed my stroker 283 (316ci... 283 bore/327 crank) to 8K on the dyno the other day, and didn't have to sweep anything up off the floor.

    It stops making power a 6K though, so that's where I'll side-step the clutch in the car.

    -Brad
     
  4. The head to use is the double hump # 3928445 with the 2.02 intakes and 1.60 exhaust valves. The con rods for 67 302 small journal are # 3927145. The 67 small journal crank thats tufftrided # 3917265. Std. bore piston for 302 11:1 comp. is #23946876, the .030 over 11:1 is # 3946882 . Cam # 3927140 duration at .050 I: 256 E: 268 lift I: .469 E: .483 centerline 112 , or cam # 3965754 which may have to have valve relief cut in pistons the duration is I: 262 E: 273 lift I: .489 E: .509 centerlie 112.
     
    Last edited: Feb 4, 2010
  5. mart3406
    Joined: May 31, 2009
    Posts: 3,055

    mart3406
    Member
    from Canada

    There's no particular magic to a a 302. Chevy only built them to be legal and as close as possible to the 5 Litre - ie 305 cubic inch limit for the SCCA Trans- AM series. If they could have used a bigger engine and been legal, they would have. If you're looking to make power a 327 or 350 will rev to 7000 and beyond, just as well as a little 302 and make more power. As far as the Factory 302 Z/28s - the '67's used standard production small-journal, 2-bolt main, 4 inch bore 327 blocks and standard 3-inch stroke, 283 small-journal cranks. In '68, and '69, they used production large-journal, 4-bolt main, 4 inch bore, 350 blocks with a dedicated '302-only' large-journal 3 inch stroke crank.

    Mart3406
    =============================
     
  6. Deuces
    Joined: Nov 3, 2009
    Posts: 17,798

    Deuces
    Member
    from Michigan

    Here's a couple of head scratchers I'll throw into the mix... The 350 originally came in the '67 Camaro SS as a base motor. My question is, was that a large or small journal block??? I've also wondered how the little 302 would have ran on the street with the famous L-79 327 cam instead of the factory solid lifter version.... And also a smaller carb instead of that huge 780 cfm Holley. It probably would have had alot better low end torque. It's a little something to think about.
     
    deathrowdave likes this.
  7. A 302/301 Should be use in a light car with at least 4.11 gears
     
  8. ALL 350s were large journal including the 67 Camaro engines. The invention of the 350 was the whole reason for going to a large journal crank. The longer stroke made for less metal between the rod & main journals. The 67 Camaro 350s were the only large journal engines made in 67. Grumpy Jenkins talks about it in his book "The Chevrolet Racing Engine" now out of print I believe but you can find them on Amazon sometimes. I've had my copy since about 1974.. For all you guys wanting to build 302s think real carefully about how you plan to drive your car. I've owned several including the 52k mile 69 Z/28 in this pic that I owned for 20 years. (please excuse the OT pic you post cops) They suck on the street. They need at least 3500 rpms to run worth a shit and they are the happiest between about 4000 & 7000 rpm. If you're gonna cruise around town in 2nd gear all the time you'll be fine but normal driving they like to load up & foul plugs. You can get away from all that with a cam swap but then all you'll have is a little smallblock. I rebuilt one a couple years ago for a buddy with a 69 Z/28 who had never driven the car or owned one. He got it all bolted up & called me & told me I fucked up his engine and that it had no power. So I took him for a ride banging gears at 7500 rpm and when we stopped he was white as a sheet and complaining that I was trying to break his car. I explained to him that those engines were designed to be run that way and they don't run worth crap at low rpms. The standard rear end ratio from the factory on the Z/28s was 3.73 but alot of guys ordered them with 4.11s.
     

    Attached Files:

    Last edited: Feb 8, 2010
    kidcampbell71 likes this.
  9. super-six
    Joined: Nov 20, 2008
    Posts: 190

    super-six
    Member


    Jeff/21 is correct. And for a street car, an M-20, not a 2.20 low.
     
  10. HEATHEN
    Joined: Nov 22, 2005
    Posts: 7,592

    HEATHEN
    Member
    from SIDNEY, NY

    Case in point----years ago, my brother owned a '69 Z/28, immediately followed by a '69 Chevelle SS 396/350HP, with a close ratio Muncie and 4.10 gears. Both cars were about even in acceleration on the street, but the big block car was WAY easier to live with in everyday use.
     
    kidcampbell71 likes this.
  11. Larry T
    Joined: Nov 24, 2004
    Posts: 7,675

    Larry T
    Member

    Actually the main reason to run a 302 is to meet a cubic inch rule or weight/cu. in. class. A well built 327 or 350 will turn as many RPMs and make more horsepower.
    .000000002
    Larry T
     
  12. So, I just happen to have a factory, short block, windage tray, and factory re pop pan 11 1/2 compression factory. Large journal 4 bolt block 69 motor
    With ported ( CJ Batten did then in the mid 1970's ) camel hump no accessory hole, big block springs. Shifted at 7200 all day long.
    Sounded like a bee in a barrel
    Rock crusher Trans, 391 gear ,8 3/4 sure grip, in a sleeper Vega. Did a lot of street racing up and down telegraph in Michigan.
    It was a friggin rocket, side step the clutch between 1 and 2 and pull the front end about 6 inches.
    What do think I should do with it ? It has been in the corner for twenty years, needs to be gone thru.
     
    kidcampbell71 likes this.
  13. Big Block Bill
    Joined: May 14, 2009
    Posts: 300

    Big Block Bill
    Member

    _______________________________________________________________

    You are on the right track. You need to be sure you have a small journal 327 so the small journal 283 crank drops in. That is what Chevy did in the pinch to come up with a motor about 305 cu in for I think trans-am racing. I know they did this for '67 and maybe '68 too. Then they got the large journal 4 bolt main block and crank to go along. That is the history of the Z-28 in a nut shell
     
  14. Big Block Bill
    Joined: May 14, 2009
    Posts: 300

    Big Block Bill
    Member

    _______________________________________________________________ You have been mis informed... the 327 didn't have 4 bolt mains although it could be converted. 4 bolt mains came with the 302 and 350 then the 400
     
  15. rcnut223
    Joined: Oct 12, 2006
    Posts: 1,233

    rcnut223
    Member
    from wisconsin

    Might have been addresses already, but the two bolt block drilled for 4 bolt caps is the strongest.

    Dirt track racers did this all the time in the day.
     
  16. Big Block Bill
    Joined: May 14, 2009
    Posts: 300

    Big Block Bill
    Member

    ________________________________________________________________

    I believe the designation of DZ is for the '69 302 block only, making them a rare item
     
  17. Larry T
    Joined: Nov 24, 2004
    Posts: 7,675

    Larry T
    Member

    Bill,
    That's kinda splitting hairs. True, you couldn't get a 4 bolt 327 but the 302/327/350 all used the same block castings in 69. They were just machined for 2 or 4 bolt mains.
    Larry T
     
  18. Big Block Bill
    Joined: May 14, 2009
    Posts: 300

    Big Block Bill
    Member

    _____________________________________________________________

    The 283 crank was a small journal forged steel piece. I doubt the 265 L-99 crank would be forged or even small journal
     
  19. Larry T
    Joined: Nov 24, 2004
    Posts: 7,675

    Larry T
    Member

    If you drilled it for splayed bolts.
     
  20. Big Block Bill
    Joined: May 14, 2009
    Posts: 300

    Big Block Bill
    Member

    ______________________________________________________________

    You are talking a 1/8"difference between a 283 and any 302,327 or 350....all had 4" bores except for the 283 with 3 7/8" bore Easy enough to check with a simple ruler.
     
  21. Big Block Bill
    Joined: May 14, 2009
    Posts: 300

    Big Block Bill
    Member

    ______________________________________________________________

    I think it is a matter of preference. You can't change the numbers. The combo works out to be just over 301.5 cu in. Old timers might call it a 301 because that is the full number size. I can't picture someone saying I have a 301 and a half cu in motor, so they left it at 301. In math you round anything more than a half up to the next number,being the combo is something like 301.59 cu in, it is rounded off to 302.
     
  22. Big Block Bill
    Joined: May 14, 2009
    Posts: 300

    Big Block Bill
    Member

    __________________________________________________________________

    That question about journal size has been argued to death over the years. If you talk to 10 engine builders, 5 will say the large journal is the best with their reasoning, the other 5 will say the small is the way to go with their reasoning. I think it has not been solved completely yet.
     
  23. olscrounger
    Joined: Feb 23, 2008
    Posts: 3,505

    olscrounger
    ALLIANCE MEMBER

    what NH bandit said--very narrow power band--not happy below 3500-327 small journal will wind high too (factory redline at 6500 on HIPO motors) with a much better power band and be much more user friendly on the street-have had both
     
  24. Big Block Bill
    Joined: May 14, 2009
    Posts: 300

    Big Block Bill
    Member

    ______________________________________________________________

    I never saw a 327 or 283 painted black from the factory. Most 283's could go .125 over, but should sonic check before spending money. I've heard the '57 block and the nova blocks were the desired blocks to go .125 over safely.
     
  25. Big Block Bill
    Joined: May 14, 2009
    Posts: 300

    Big Block Bill
    Member

    _______________________________________________________________

    There is no reason not to build that motor. It doesn't make torque. If you are looking for torque, you build a bigger motor, 383 on up, 383 being a minimum. If you have the parts to build the motor, by all means build it. If you have to buy everything, start with like a .030 over 327(331) or bigger and have fun. If you are building a car for a certain class that requires a motor that small, you have no choice.
     
  26. Big Block Bill
    Joined: May 14, 2009
    Posts: 300

    Big Block Bill
    Member

    ________________________________________________________________

    You should have no problem getting the pistons. You might have to buy a quality piston though and that gets costly, but getting the propper pistons are no big deal
     
  27. PSB
    Joined: May 28, 2009
    Posts: 70

    PSB
    Member


    DZ is for a 69 Z28.. Mo is for a 68.. The DZ is not just a 350 block. It is a High Nickel alloy block .. If its a DZ it is High in Nickle,
     
  28. 4ever18
    Joined: Nov 1, 2007
    Posts: 466

    4ever18
    Member

    I'm glad to see a renewed interest in this combination. As a kid in the 60's I grew up hearing stories of 301s in '55/7 Chevys and well they performed. But being a kid and with almost every year the engine size and horsepower offerings in new cars becoming larger, I grew up thinking that the only thing better than cubic inches was cubic feet! Bigger is better. It was only much later that I learned that Chevrolet's "mouse that roared", the Z28 302 was pretty much the same engine that the "old guys" had talked about for years. Given that most of the '55/7 Chevys weighed less than the '67/9 Camaro, I no longer doubt that these cars did run well - at least for drag racing. I've never driven one of these little beasts, but that will soon change. Hopefully, sometime in the next few months to be able to report how well one of these engines performs in my '34 Ford 5 window coupe. I've already narrowed a '64 Pontiac rear for the car. I have a 3.90 posi third member for it. The transmission is a Borg-Warner T10 4 speed. Old school all the way, Baby!
     
  29. Big Block Bill
    Joined: May 14, 2009
    Posts: 300

    Big Block Bill
    Member

    ______________________________________________________________

    I have never used either option but I hear you have 2 ways to go. Bearing spacers or oversized bearings, which I'd think was the better way to go, but the bearings cost a bunch
     
  30. Larry T
    Joined: Nov 24, 2004
    Posts: 7,675

    Larry T
    Member

    As to why a 302 was a popular engine, it's because of several different things.

    The biggest is that all of the engineering and development work was done (because of cu. in. rules and weight. cu. in. classes) to wring every last horse out of the engine. Put together an engine according to standard Chevy performance specs and, bingo, you're gonna have an engine that is real competitive with other engines of the same size. And it doesn't cost as much as most other manufacturers engines of the same size.

    For street driving and torque, an engine has to move a certain amount of air to make a certain amount of torque. Since a 302 can't move the amount of air a larger engine can at matching RPMs then you have to turn it tighter than the larger engine to make the same horsepower. With the shorter stroke and less piston speed, you CAN turn the engine tighter with marginal parts with less chance of making a paper weight out of the whole mess. But it's a trade off, like folks have said it's a dog at low rpms.

    As far as torque goes, since horsepower is a mathmatical function of measured torque and rpm you're really figuring out what rpm range you wanna run in and build your engine for horsepower AND torque in that rpm.

    I guess the shop has warmed up a little, better get to work.
    Larry T
     

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