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Technical 6-71 on 383 Chrysler

Discussion in 'The Hokey Ass Message Board' started by Pickled_asparagus, Apr 26, 2015.

  1. Pickled_asparagus
    Joined: Aug 12, 2009
    Posts: 47

    Pickled_asparagus
    Member

    Was wondering if anyone out there has put a Blower on a Chrysler 383. I'm mainly interested in reference dimensions as I'm currently blazing my own trail creating a manifold. The motor is currently in my T-Bucket topped with a six pack setup but I have a 6-71 I'de like to install. I plan to have a short block done to knock down the compression with a blower cam etc...

    Nobody really makes purpose built blower manifolds for 383-400 chryslers so hopefully I can figure this out and share. BDS, Dyers, etc. have manifolds however it appears they are just modified dual quad manifolds with an adapter welded on, which is what I have and plan on doing without forking over $1600 for just a manifold.

    I have measured the bottom of the blower and the top of the offy intake, and modeled up a "dry" run in Solidworks (just like they did in the 50's). I have the advantage of being able to lasercut a plate out of thinner steel to mock up before I buy a 1" plate of aluminum for the real deal (again, just like in the 50's). My question is, how do I get the currect length for the drive and position the blower on my adaper plate? I currently set it up so that the blower would be centered on the Offy intake. Can I just get a longer drive snout to accomodate? What is the proper method for measuring this? I do have access to a full mockup motor with balancer and heads installed. Once I have all that figured out I will worry about milling the top of the offy intake flat.
     
  2. earlymopar
    Joined: Feb 26, 2007
    Posts: 1,082

    earlymopar
    Member

    I would get the pulleys you're going to use bolted on the engine and then align the blower pulley with the crankshaft pulley. I think you can do a lot of paper work and CAD calculations but unless you have real hard (reliable)numbers, the results aren't going to be accurate. I also don't think you need to go to that level of work anyway.

    - EM
     
  3. Pickled_asparagus
    Joined: Aug 12, 2009
    Posts: 47

    Pickled_asparagus
    Member

    340 and 383 are very different with the 340 being a small block. So if I buy the crank hub I can build backwards from there? Any preference on supplier? I was going to use Dyers because they are closest to where I live. May give them a call this afternoon to see how much knowledge they'll share based off of buying a drive etc...

    I would like to make a CAD machining drawing of the plate to share on here so others can use.

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  4. porknbeaner
    Joined: Sep 12, 2003
    Posts: 41,384

    porknbeaner
    Member

    No a 383 is a low deck big block and a 340 is a small block. ^^^ Well not all 383s were low deck motors the early 383 was a tall deck but very rare.

    I don't have reference numbers. I don't know what you are using for a blower snout but I do know that they are not all the same length. What I would do is bolt it all together and then slide the plate until the pullies were lined up and mark it LOL just like they did in the '50s. :D
     
    Last edited: Apr 27, 2015
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  5. Pickled_asparagus
    Joined: Aug 12, 2009
    Posts: 47

    Pickled_asparagus
    Member

    Ya, I'm new to the blower world. So in order to do as you said I need a drive (for a 383 as a starting point), a belt, and a crank hub? The blower has a drive and cog for a SBC on it right now (from a friend of mine) but based off rough measurements its about 6" short.

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  6. porknbeaner
    Joined: Sep 12, 2003
    Posts: 41,384

    porknbeaner
    Member

    The snout is not necessarily engine specific, if you find a snout recommended for a B/RB or a B/B motor they will be the same length. You just need to find a drive with a long snout or on with a longer snout then what you are using. probably 10" is about as long as you are going to find. I may have seen a 12" at some point though so don't hole me to that.

    Get what you are going to use and go from there. Make life easy on yourself.
     
  7. 73RR
    Joined: Jan 29, 2007
    Posts: 6,252

    73RR
    Member

    Gale is my 'blower-guy' 808-329-9037 he is usually very eager to help...years and years of experience.

    .
     
  8. RacerRick
    Joined: May 16, 2005
    Posts: 2,753

    RacerRick
    Member

    We put a 6-71 on my friends 451 stroker using a BDS manifold. We were using MP Stage VI heads so we used the 440 manifold. Since my friend is an old fuel racer he setup the blower himself using a BDS drive kit. The kit is the same as the 426 hemi kit and is pretty common. BDS makes a manifold for the 383 but it is the 2 piece one and very expensive.

    Is there any reason you want to use a 383? Of the chrysler big blocks, a 383 would actually be one my my last choices.

    The mains support are thin on a 383, and tend to crack when you really start making some power. I would prefer a 400 block since the mains support on a 400 is much thicker.- its actually the strongest big block mopar block.
     
  9. porknbeaner
    Joined: Sep 12, 2003
    Posts: 41,384

    porknbeaner
    Member

    The only problem I see using a 440 manifold for a blower on a 383 or a 400 is that they 440 is a raised block ( tall deck???) and it would be a bit wide.

    I am going to go out on a limb here and say that he is interested in using s 383 because that is what he has. The suggestion of the 400 block is good and lots of times we all suggest a different rout than the one being followed but some times some of us just have to use what we have and can't really go looking for something different. Anyway not busting your chops here just making an observation.
     
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  10. Pickled_asparagus
    Joined: Aug 12, 2009
    Posts: 47

    Pickled_asparagus
    Member

    Correct. There is a running 383 in the car right now (should be around 9:1 but I will check this). I figured if I went with a different Chrysler motor I would need a forged crank and rods when my 383 already has them. Your point on the main webbing is well taken. I don't know what the availability is on 400 blocks (can't imagine a smogger 400 goes for all that much) and my forged 383 crank would drop in.

    The flipside of this is how much power do you really need to make to crack main caps and block webbing? (Asking those with experience.) Say you have an NA 450hp motor and a "bolted-on" 450hp Blower engine. Do the internals of the blown engine get put under more stress than the NA motor of equal power? Although strength is never a bad thing, I'm trying to make educated decisions on which direction to go with cost and currently owned (or fabricated) parts in mind. I'm open to buying more stuff, just want to get a feel for if it's necessary from people who have some experience.

    Thanks for all the responses!
     
  11. 73RR
    Joined: Jan 29, 2007
    Posts: 6,252

    73RR
    Member

    There are actually two different 400 blocks and one does have significantly thicker main webs. IIRC, the 440source web site has a detailed photo section on the subject.
    The difference that I have found in NA vs. pressurized engines is that connecting rods seem to be a weak point under a blower. Spend a little extra on some good ones.
    As far a MotherMopar blocks-cranks-rods and general such parts I have faith in any B-RB not needing much
    'extra' help until in the range of 500hp or so. Your results may vary.

    .
     
  12. I will vouch for both Gary and Gale! Stand up Gentleman, and if you ever needed anything Mother Mopar related or Blower info- These are the Guy's! They BOTH get my stamp of approval!:D
     
  13. Pickled_asparagus
    Joined: Aug 12, 2009
    Posts: 47

    Pickled_asparagus
    Member

    Awesome! Thanks much! Do these guys have a buisiness or are they just up to answer random hotrod phone calls?? :)
     
  14. They are both in the biz----- Gary can be found here= Check, Gale is only a phone call away.......
    VERY smart cookies if I must say,and I DO. It will be worth your while............:D
    Many years of experience,and like yourself,a lot of Q's..... they are willing to help,and offer vast knowledge. I would be lost with my stuff if it wasn't for them.......
    not a sales pitch,but where credit is due........
     
  15. el Scotto
    Joined: Mar 3, 2004
    Posts: 4,183

    el Scotto
    Member
    from Tracy, CA

    Even the cast crank B/RB models can take a ton of power. One of those Chry-Pile mags did a buildup years ago using the cast junk and made over 500 without much modification, just a rebuilt shortblock, cam, mild heads.

    I've got a '73 motor home 440 swinging factory forged guts and heavy duty piston I've got a 6-71 strapped to. Once I get the blower drive set up I'll figure out which car I have that needs a slightly overdriven blown 440.

    1970 Challenger or 1956 Chevy? Model A coupe on deuce rails? Choices, choices...
     

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  16. porknbeaner
    Joined: Sep 12, 2003
    Posts: 41,384

    porknbeaner
    Member

    The pan rail on a B block MOPAR hangs below the main center and the really serious ones are cross bolted. The lower end itself in its natural state is pretty stout.

    73RR is correct the rods are going to be your weak link in a force fed motor. But Mother MOPAR makes some pretty stout ( if not too heavy) factory rods.

    Here is a tid bit that I picked up from someone at MOPAR performance in the '90s. it doesn't pertain to a blown motor but it is an interesting tidbit anyway. I was doing some research on the cast lower end as far as necessity for a street strip motor was concerned. The man I was talking with told me that internally balanced and set up properly that the cast crank and corresponding rods from say a mid '70s external balance B/RB was good for 700Hp with a 6.5 to7K redline. That they had tested them to that.

    Anyway so much for useless knowledge from the beaner.
     
  17. mohr hp
    Joined: Nov 18, 2009
    Posts: 220

    mohr hp
    Member
    from Georgia

    I wouldn't be afraid of a converted N/A manifold with a plate welded on, we used to think those 80's Dyers based on a SINGLE 4 barrel were junk, but then the hi helix and screw stuff came along and they all made huge power feeding through a tiny opening. Also, power level isn't such a big factor in lower end strength requirement as much as detonation tolerance (crankshaft jumping around) and RPM level. Plenty of 383's were supercharged in the early 80's with good results.
     
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