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Hot Rods dodge poly and hemi

Discussion in 'The Hokey Ass Message Board' started by silent rick, Mar 3, 2017.

  1. silent rick
    Joined: Nov 7, 2002
    Posts: 3,868

    silent rick
    Member

    i'll be picking up my low deck dodge 241/270 short block next Friday(thanks Jack).

    it's got me on the look out for hemi heads. then I got to thinking. I already have the firedome in my 46, what I need is a poly. everybody is taking off their poly heads to turn their mills into hemis. poly heads should be laying all over the place.:)

    so what parts do I need? all I have is a rotating short block. poly pistons will have different valve reliefs. are the intakes the same? I hope the intakes are the same. are all poly heads the same? is there a better choice?

    let's share the knowledge.
     
  2. brigrat
    Joined: Nov 9, 2007
    Posts: 4,779

    brigrat
    ALLIANCE MEMBER
    from Wa.St.

    I have some ready to go 259-260 Ploy heads, converting the Poly to Baby hemi as you said so lot's of extra parts, push rods, pistons, VC's, etc....................................................
     
  3. George
    Joined: Jan 1, 2005
    Posts: 7,015

    George
    Member

    To make a poly you need the complete head assymbly, push rods, ex mans. On @ least some of the low comp low decks the factory apparently put hemi pistons in some Polys & vice versa. Guess the low comp pistons & cam didn't create interference. With high comp pistons 7 higher lift cam proper pistons would be the way to go. Advertised C/R on 241 was 7 or 7.7:1, one measured an actual 6.19:1. Don't know if high comp poly pistons are available.
     
  4. silent rick
    Joined: Nov 7, 2002
    Posts: 3,868

    silent rick
    Member

    do the two use the same water pump/crossover and intake manifolds? as long as they're both low deck.
     
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  5. Jalopy Joker
    Joined: Sep 3, 2006
    Posts: 23,019

    Jalopy Joker
    Member

  6. 35desoto
    Joined: Oct 6, 2009
    Posts: 760

    35desoto
    Member

    Water pump crossover and intake manifolds are all interchangeable
     
  7. sunbeam
    Joined: Oct 22, 2010
    Posts: 4,206

    sunbeam
    Member

    If it is a 270 I have a set of ..040 over NOS poly pistons for $150. If its a 241 you may have to open up the push rod holes.
     
  8. dang...I'm so far behind.....tear downs are in my future....241 poly/hemi -270 poly - 315 hemi....
     
  9. jack_pine
    Joined: Jan 20, 2007
    Posts: 343

    jack_pine
    Member
    from Motor City

    I have a 270 poly and trying to figure out headers. I was thinking of flanges from Headers By Ed and then adapting to Sanderson headers for Dodge hemi. Anybody tried this?

    Sent from my SAMSUNG-SM-G870A using The H.A.M.B. mobile app
     
  10. 35desoto
    Joined: Oct 6, 2009
    Posts: 760

    35desoto
    Member

    Your better to use the header flanges and make your own. The exhaust ports are not the same and all you will do is cut up a perfectly good set of headers for the hemi and create a patchwork poly set
     
    jack_pine likes this.
  11. 35desoto
    Joined: Oct 6, 2009
    Posts: 760

    35desoto
    Member

    Our if interest does anyone have a good low block crank? Good friend lunched his 259 Plymouth poly and the crank is the last part we need for a darn good rebuild.
    Any 241 or 270 crank will fit
     
  12. Andy
    Joined: Nov 17, 2002
    Posts: 4,445

    Andy
    Member

    I have a nice set of 241 heads,pushrods,rockers,bolts, and covers for $300.
    The crank has one journal worn .016. Machine shop says it will need ground .030 on the rods.
     

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