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Mild 400ci stroker build, opinions?

Discussion in 'The Garage' started by madmike, Mar 1, 2007.

  1. madmike

    madmike 1/2 ton status

    Jan 23, 2002
    Likes Received:
    I'm thinking of building a 400ci small block that I have laying around, and turning it into a mild stroker engine for daily driving/light towing in a late 70's K20, SM465/NP205 with 3:73 or 4:10 gears, with 35's probably being max tire height.

    I have used a Speed-o-Motive stroker crank kit in my 454 (now a 489), with great success.

    I'm just looking for thoughts, opinions, and issues on building a nice, mild, stroker 400 mill. Also, would the stock cast iron cylinder heads be worth re-using, if in good condition?


  2. CDA 455

    CDA 455 3/4 ton status

    Jun 2, 2006
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    43rd State
    What year is the 400CIB?

    From what I can remember (I could be wrong), late '70's 400 blocks suck due to cooling problems.
  3. rjfguitar

    rjfguitar 3/4 ton status GMOTM Winner

    Aug 28, 2002
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    They all cool just a like, there is little difference in the blocks from early to late model.

    The problem with a stroker kit for a 400 is it makes it a 430ish and is not very popular. Last time this conversation went on there wasn't much for piston selection and IIRC you would have 10.1:1 or more on a 76cc chamber. Also, I think there was some wrist pin problems.

    The stock heads choke out a 350, they want to completely cork a big 400..... Go with an aftermarket head if you actually want to make some good power.

    AFR says if I would have went with their heads on my 406 I would have 70HP more over my stock heads. Other sources confirm that.
  4. twoslo4five0

    twoslo4five0 3/4 ton status Premium Member GMOTM Winner

    Oct 5, 2006
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    Living in a dump, VA
    i know a guy with a ohio rotating assembly in a 400 stroked to a 434...it will run all day and night...theese days they consider a 406 a stocker...i built a 408 (.40 over) and i ran casting 241 heads double humps and it bumped my compression up to 11.5 to 1 with a flat top pistion..i ran a solid cam and had aroung 500 hp...you can run 350 heads or 305 heads but you have to drill the steam holes 305 and 350 heads dont run steam holes....another buddy of mine ran vortecs on a 400 and it kicked a$$...he had a ton of power...
  5. folkenheath

    folkenheath Worthless Trash Premium Member GMOTM Winner

    Nov 12, 2004
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    If you want it relaible go for a 421, I've heard the block has to be sonic checked and near perfect alignment to go with the 434 or you get into water jackets when grinding for clearance. Unless you have an aftermarket block $$$. If you want really cheap, go with vortecs and a pretty mild cam. But to be honest I don't know if it's worth the trouble for the extra 15 cubes to go stroker for your purpose (and I do like stroker motors). You would probably be better of saving the money on the shortblock and spending it on the heads. Just make sure you get the correct compression pistons for the heads you plan on using so you don't run into detonation issues. I have an excel spreadsheet I wrote that calculates static and dynamic compression, if you want it I can send it to you.

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