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383 Questions?

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by LittlePig, Aug 10, 2000.

  1. LittlePig

    LittlePig 1/2 ton status

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    Why is it everyone who is down on the 400 for being externally balanced (as opposed to having siamesed bores so it doesn't cool as well) in the same sentence says "make a 383 instead since they make so much torque"? The 383 is externally balanced too, since it is made using the externally balanced 400 crank.

    As a corollary to this, do any aftermarket manufacturers make stroker cranks for the 350? As I understand it, in order to use the 400 crank, the mains have to be turned down some ungodly amount. I would think there would be a pretty good market for a long-throw internally balanced crank for the 350, so you could get the stroker torque advantage without dealing with external balancers or way-undersized mains. Any help on this one?
     
  2. tRustyK5

    tRustyK5 Big meanie Staff Member Super Moderator GMOTM Winner Author

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    I don't know why anyone would slag the 400 for being externally balanced either, so is the big block! Good question on the crank, I have seen a number of "stroker" kits advertised and I got the (mistaken maybe) impression that they were using custom aftermarket cranks. Check out the P.A.W. ads.
    ...later

    Rene 81 Jimmy,350,SM465/NP205,FF14 bolt,HD Dana 44,3.73's,4"susp.,35"Grabber MT's,body in progress
     
  3. LittlePig

    LittlePig 1/2 ton status

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    I just looked at the PAW ad. They say "Custom ground crank" and in small type at the bottom they say "requires harmonic balancer from 400 Chevy", which sounds a lot to me like they grind down 400 cranks for their kit.
     
  4. LittlePig

    LittlePig 1/2 ton status

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    Just a side note, Lunati has a Nodular Iron crank with a 3.750 stroke and 350-sized mains. I believe this is the stroker crank, but they don't list prices, and even a nodular from lunati ain't gonna be cheap. Anyone know of any other suppliers that might make a stroker crank?
     
  5. Emmettology 101

    Emmettology 101 3/4 ton status

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    Summit lists a stroker crank, well they list it as a 383 crank, but I am not sure if it has a note that you need a 400 balancer though.

    Mike [​IMG]
    1982 GMC Jimmy - <font color=green>Emmett</font color=green>
    http://emmett.coloradok5.com
     
  6. LittlePig

    LittlePig 1/2 ton status

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    Nope, according to Summit's website, their crank requires an external balancer too.
     
  7. BUDDY

    BUDDY 1/2 ton status

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    Check out SCAT cranks. They make cast steel stroker cranks for the 350 for just about any displacement you can think of and they're cheap too. About $250.00. It uses the same journal size as the stock 350 but has a 1/4" more stroke. They even make them internally balanced so you can use a standard 350 flywheel and damper. Just do a search for "scat cranks" and you'll find all kinds of stuff.

    HTH

    Buddy

    I've got my dream truck and it's a 72 K-5 that is getting there!!
     
  8. tRustyK5

    tRustyK5 Big meanie Staff Member Super Moderator GMOTM Winner Author

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    If I use the word "scat" in a search query, cranks are the last thing that come up. Yuck
    ...later

    Rene 81 Jimmy,350,SM465/NP205,FF14 bolt,HD Dana 44,3.73's,4"susp.,35"Grabber MT's,body in progress
     
  9. ken

    ken 1/2 ton status

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    400s are the way to go. But 383s are the current "flavor of the month". Both are externally balanced. The only big block that is externally balanced is the 454 and 502. Summit sells new 383 cast cranks for $320, forged steel $550. This is the only way to go if you just gotta build a smaller displacement, less HP and torque (than a 400) SB Chevy at nearly double the price. Good luck! Me, I'll stick with my big blocks!!

    ken
     
  10. 90K5

    90K5 1/2 ton status

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    I heard somewhere that GM was making a 383 Vortech crate engine. Does anybody know if this is true? If it is I know what my next engine will be

    90K5
     
  11. dumbfounded

    dumbfounded 1/2 ton status

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    If you really think about this the 86 and later 350 can be defined as externally balanced b/c the flywheel/flexplate is NOT neutral balanced. As for external balancing It is all the same as long as all the parts remain in sync. 400's have been known to have heating problems. The cylinder walls are thin and can have localized boiling around the cylinders for a non race vehicle they should be fine. A high flow water pump would take care of most problems. You can also "destroke" a 400 to a 383 with the use of a 350 crank. This means a shorter stroke than a 350 stroker and properly balanced can make a mean high reving machine. Maybe not what you need. Also look into a really good machine shop you can take a 400 crank and with some time and careful work a good machinest can make a 400 crank internally balanced so you can use a 350 flywheel. This is a pretty trick idea b/c the money saved if you have a manual transmission would pay for the balance. Most machine shops would charge $400-500 for balancing the crank. Me I'd just go for the cubic inches and stroke a 400 to a 420 but that's a high dollar crank to stick in there. Scat does make a stroker crank which is balanced identically to a 86 and newer 350. But for a price which isnt bad. Just depends on how much room in your pockets or on the good old plastic. Look in some super chevy magazines they may have articles. I know the corvette mags have them.

    Love, Peace, and Hair Grease...........
     
  12. Blazer79

    Blazer79 1/2 ton status

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  13. BUDDY

    BUDDY 1/2 ton status

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    look up "scat cranks" (both words) and lots of stuff will come up.

    buddy


    I've got my dream truck and it's a 72 K-5 that is getting there!!
     
  14. Burt4x4

    Burt4x4 3/4 ton status

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  15. richardc

    richardc Registered Member

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    Call SDP. Last time I talked to them, gm was having trouble in the test phase. I elected to build my own. I do everything for 3k. Not just a long block.
     
  16. richardc

    richardc Registered Member

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    Lots of posts here, I won't take time to read, so this might be a repeat. The 400 is not dog doo. It got a bad rep, find someone who builds small blocks for a living, he will probably tell you what follows. Every hot rodder in this country is hording them up as I type. The problem was the goofy rod length of 5.65. This is corrected by using 5.7" rods and the correct after market piston. If you build one right, you will not have over heating. And you will have (don't hit me big blocky guys) tremedous torque. That said, 383s work, there will not be any over heating. Am I gona stuff a 406 in my truck? No. But if I had one to start out with I would. There are many crank manufactures scat, lunati, etc. If you're into building motors, I highly recommend chevy performance and get the speedomotive catalog. I've got one of their cranks, and it's new not custom ground. On the trail, 350-370 horses is way plenty. Move up to the 400+hp with the 406 and it's probably too much. If you got the 400, all you need are the 5.7 rods and the pistons and some spare change for machine work. Think about this, I'm gona have 90$ in machine work to clearance the block for the crank + $300 for the crank. If you've got the 400 go for it. I'm buying a block for $50 and storing it away. The original 400s were also way under compression. Bump one up to 9.5-10:1 and it will go.
     
  17. Blazer79

    Blazer79 1/2 ton status

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    Can you explain why a 5.7" rod is better than a 5.65" rod? I know I'll buy a stroker kit this or next year, so I want to learn everything I can.

    <font color=blue>//////
    http://blazer79.coloradok5.com
    </font color=blue>[​IMG]
     
  18. richardc

    richardc Registered Member

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    why 5.7 rod is better

    Why longer is always better right? ;> I just know what I've read, this is straight out of speedomotives catalog: "This kit corrects the short rod problem which earned this motor a reputation for overheating and oil consumption. The longer 5.7 rod maintains a superior rod angle reducing cylinder wall distortion and loss of ring seal at bottom dead center. Power is also increased by reducing the tremedous amount of wear on the thrust or outside facing wall of the cylinder bore. SOM claims 420 ft lbs at 3000 rpm. with a 10-1 compression engine." So, the side skirts and pistons scuffed at the BDC which caused cylinder walls to distort and heat(ie blow head gaskets). Chevy High Performance magazine April 2000 had a 406 build up article where they built a streatable small block 468 ft lbs at 3000 rpm max hp 455 at 5500 rpm and max torqe 498 at 3800 rpm. Man that makes my old LT-1 Z28 look like a dog! Hot rodding has changed very much since I quit in 1978( I sold my Z28 because I could not afford the av gas and could not afford to replace the engine) So today, we can do more with less compression. That 406 that CHP built had 9.7:1 comp ratio. That's what (in theory, I don't have the block yet) my 383 will have. I still think a re-buildable 400 is one way to go. Correct the rod problem, use a good oil pump, a high flow water pump, mill the heads/block and with todays new collant tech (additives, fans, etc) you will not have a heat problem. You may however, have a u joint problem ;> PS if anyone has any 400s in the TX NM area, I haul them away for free. haha
     
  19. blazer72

    blazer72 1/2 ton status

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    Re: why 5.7 rod is better

    Yea the 400 was bad only over a 1,000,000. made most were in trucks Van and the like. 400 do not like high RPM due to the rod being shorter. 400 do make the tork at lower RPM. 400's do over heat with head other that 400 heads. 400"S DO NOT OVER HEAT EASLYER THAN ANY OTHER SB!!!!.

    And any 400 block is worth 200.00 and up, a crank is worth 350 and up. All 400's had pink rod's and forged cranks.

    400 had a lower red line that other SB (about 4200 to 4500 tops)

    I have 5 of them the last one I got was running and I payed 600.00 for it a I got a steal!!!!!!

    I understand the jeep thing I drive a BLAZER!!

    Ken
     
  20. BigBadBowTie

    BigBadBowTie 1/2 ton status

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    I just got done building my 383Stroker. One of the reasons I went with it as do many people is they already have most of the parts, where they'd have to buy everything for the 400. My specs are as follows.

    350 4bolt main
    Chevy 350 6.00" rods
    Scat 383 Crank 9-350-3750-5700
    Keith Black Pistons KB121 (required for the longer rods)
    Moly Rings
    Vortec Heads (Factory new, resurfaced & valves re-lapped)
    Competiton Cams XTreme Cam CS X4 262H-11
    Competiton Cams Valve Springs 981-16
    Competiton Cams Rail type roller tip rockers 1417-16
    Edelbrock Performer Vortec Intake Manifold

    The block was line honed, balenced & blueprinted. Running 9.1:1 Compression, 795CFM Q-JET, JBA Shorty Block Hugger Headers, Hooker 2 1/2" mandrell bent dual exhaust, 3 Chamber Flowmasters.

    The total on this motor completely assembeled was $3200.00

    Est HP 425
    Est Torque 435



    <font color=purple>Rick
    86 K-5</font color=purple>

    http://www.BigBadBowTie.ColoradoK5.com
     

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