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Mopar BB Interchangeability ?'s

Discussion in 'The Hokey Ass Message Board' started by Chriso.0, Jan 12, 2013.

  1. Chriso.0
    Joined: Oct 20, 2012
    Posts: 20

    Chriso.0
    Member

    I have a 62 Dodge 880 with a 361 that's losing a lot of compression. I found a 400 with a date stamp of 77 to replace it. From what I've been able to find out, it should work except for the fact that the crank is lighter. Would a harmonic balancer and heavier flexplate fix the problem or is there a better way to go about it? I'm assuming I'm not the first person to try to mix these models of engine.
    Thanks,
    Chris
     
  2. the 77 crank is cast the 62 is forged changing anything but the crank itself isnt going to do anything excpet throw the engine out of balance

    there is nothing wrong with the cast crank unless you making more then 600 horses
     
  3. el Scotto
    Joined: Mar 3, 2004
    Posts: 4,357

    el Scotto
    Member
    from Tracy, CA

    The 400 is externally balanced and the torque convertor hub is a different size.

    Find a 1967 and earlier B/RB and it will bolt right in and up to your existing tranny.
     
  4. Hemiken
    Joined: Sep 21, 2012
    Posts: 492

    Hemiken
    Member
    from Australia

    A 400 is just a big bore 361, same deck height. Your 361 will have different heads but still bolt straight on to a 400, therefore the exhaust manifolds are different, but the intake manifold will bolt straight on from either engine. I agree, leave the 400 crank in it, it will do the job fine. Everything else should bolt straight up for you. Depending on what box you run, will determine what you will have to do with a convertor if it is auto.
     

  5. skicker
    Joined: Jan 10, 2013
    Posts: 12

    skicker
    Member
    from Gone

    If the 400 and the 361 both have 727's behind them you can make this work by simply using the 400 torque converter. ;)
     
  6. Chriso.0
    Joined: Oct 20, 2012
    Posts: 20

    Chriso.0
    Member

    Thanks guys. I just got more information here than I was able to find on a plethora of MOPAR message boards. The 400 is a running, non leaking engine that in getting for 150 so I'm glad I'll be able to make it work ( and add a bit of displacement :p).
     
  7. alphabet soup
    Joined: Jan 8, 2011
    Posts: 1,471

    alphabet soup
    ALLIANCE MEMBER

    I don't think you can use the 400 converter. Splines in the front pump are not the same. However Mopar Performance used to sell a balancing kit with weld on weights. And I think some of the aftermarket trans people sell a flex-plate to do this conversion.
     
  8. im not sure either on the converter i do know the 77 converter is a lock up or should be anyway

    im fairly certain the splines are the same though if you order a converter for a 727 or 904 all they want to know is if its a lock up or not
     
  9. Chriso.0
    Joined: Oct 20, 2012
    Posts: 20

    Chriso.0
    Member

    I looked into it and I can find 727 torque converters with a combination of all the different options and sizes so when I pull it all apart I'll just have to measure everything. With a new torque converter, I'm still getting a bigger motor for less $$ than a re-ring kit.
     
  10. dartracer
    Joined: Apr 18, 2009
    Posts: 241

    dartracer
    Member

    Just drop it in, B&M makes a flex plate to go between your cast crank and zero balance converter. Everything else should bolt up.
     
  11. Chriso.0
    Joined: Oct 20, 2012
    Posts: 20

    Chriso.0
    Member

    Problem may be solved. The guy has the 727 that came with the engine. If my push-button shifter will work with the trans, the car should be back on the road in a couple days with tons of left-over money to make it prettier.
     
  12. dartracer
    Joined: Apr 18, 2009
    Posts: 241

    dartracer
    Member

    Push button shifter will not work on a later 727.
     
  13. fiveohnick2932
    Joined: Mar 29, 2006
    Posts: 889

    fiveohnick2932
    Member
    from Napa, Ca.

    That low compression 361 probably still has more compression than a 77 400. Get a b&m flexplate and that will solve your cast to forged converter issues but you still have the early crank flange. On top of that your crank pulley will not fit because the balancer has a few bolts offset from the standard 6 bolt circle. Maybe a valve job would be your best bet for that 361 if your cylinders are not too bad.
     
  14. fiveohnick2932
    Joined: Mar 29, 2006
    Posts: 889

    fiveohnick2932
    Member
    from Napa, Ca.

    I think that early trans has a companion flange and not a regular slip yoke. Look into that valve job buddy!
     
  15. if he uses the pulleys from the 77 on the 77 he wont have aproblem there

    yeah there is the issue of the drive shaft the 62 probably does have the ball and tunion front ujoint
     
  16. yep,what the others said.use a new flex plate with weights on it for a cast crank.summit sells various brands.do not use mp performance weld on weights,wont work.
     
  17. As stated, the push-button shift will NOT work with the later 727, nor will the early ball and trunnion driveshaft. If your early tranny is good, it'll physically bolt up to the 400, and you can keep the push-button shifter. IIRC, you can use the 400 crank, balancer, converter and the B&M flexplate. The 400 heads have hardened seats, where the 361 doesn't. The exhaust manifolds will swap, and the 400 units have better flow than the 361 logs.

    Sounds like a good, economical swap.
     
  18. Chriso.0
    Joined: Oct 20, 2012
    Posts: 20

    Chriso.0
    Member

    So, 77 engine with new flexplate on 62 torque converter and trans. Thanks again for all the help, gentlemen. I'll hopefully let you know how it went next weekend.
     
  19. monc440
    Joined: Feb 1, 2011
    Posts: 260

    monc440
    Member

    Pro's
    400 has more cubes (no replacemnt for displacemant)
    400 has better flow heads with hardened seats.
    361 heads are closed chamber around 72-74 cc for better compression.

    Cons
    400 compression is around 8 to 1 (I have a 400 on the stand at home now that the pistons at TDC are 0.180 in the hole and I have seen late 70's 440 .210 in the hole). I agree that your pumping 361 still has more compression than the stock 400.
    400 heads have open chambers around 88 to 90 cc (making it worse for comprssion)
    Need a weighted flex plate to mate to the early trans and converter. (yes the splines on a pre 65 727 input shaft are differant than post 65)
    Cam in that stock 400 will not be all that good.

    If I were you this is what I would do (I have accually done this for many post 73 440 and 400 engines over the years to getem moving on a budget)

    Pull the 361 heads and have them freshend up. At a min put new valve seals in them. You will loose a little flow with these heads but you gain more HP with the better compression. Your 62 heads might have hardened exhaust seats but prob not. I don't worry about the unleaded gas hurting the seats as long as you keep the engine temp down you shouldn't have problems. I have a 383 with 63 heads with about 70,000 miles running unleaded with no problems.
    Pull the 361 cam and lifters (number the lifters to match the cam)
    Order a set of steel shim head gaskets from mancini racing, DO NOT use the felpro perma torque. (The steel gaskets are only 0.021 thick and the felpros are twice that and will add to the already challenged compression)
    Put the 361 heads, cam, lifters and timing chain in the 440.
    Use the 400 manifolds.
    Use the weighted flex plate to mate the 400 to the push button 727.
    Use whatever front end pulley system you want just make sure you use the 400 balancer. All the other 361 parts will bolt up to the 400

    This setup will get you "around" 9 to 1 compression and usually a bit better. If you get into trouble or want more B & RB Mopar info just PM meI'll be happy to help.
     
    Last edited: Jan 18, 2013
  20. I would just throw the 400 in there and drive it - build a better 400 later.

    I have built a few 400's the cheap way - mill the heads .060, put a street Hemi grind cam in it, good carb and intake, 1 3/4' headers and go hunting. Best one I built I pocket ported the 452's and it ran hard.

    With the stocker I would look at changing the cam to a Magnum grind, something around 268-270 duration, four barrel and recurve the distributor, I bet it will surprise you, even with the 7.5:1 real compression.
     
  21. 73RR
    Joined: Jan 29, 2007
    Posts: 6,538

    73RR
    Member

    I think far too many folks like to dis the 400 as some kind of anemic has-been without ever having had a fresh one to actually drive. The other issue is folks simply looking at a motors manual and seeing the numbers change for 1972 but having no clue as to what was actually happening.

    The heads are very good even with a large chamber. Ports and cooling are excellent.
    Depending on the application, some 400-4 had decent cam profiles. If you want to swap cams there are plenty for use with low c/r engines.
    http://www.crower.com/catalogsearch/result/index/?cat=1541&q=chrysler

    There is no shortage of intake systems for the B engine.

    .
     
    Last edited: Jan 18, 2013
  22. well the 452, 346 casting heads are the same as the 906's from 68-70 just have harden valve seats

    ive had acouple 400's i like em but i like 383's and 440's better
     
  23. Hemiken
    Joined: Sep 21, 2012
    Posts: 492

    Hemiken
    Member
    from Australia

    The 400 is the biggest standard bore Big Block Mopar made, they are 20thou larger than a standard 440 bore size, they are an excellent choice as a standard replacement and also a very desirable foundation for a modified stroker engine, you can not go wrong with a 400 Mopar.
     
  24. 270dodge
    Joined: Feb 11, 2012
    Posts: 742

    270dodge
    Member
    from Ohio

    Mopar changed the input spline count in mid 1967 from 19 to 24. The later torque converter with the 24 spline converter, if adapted with a special flex plate, might bolt up but you'll go nuts trying to figure out why the car wont move! The best approach to this is to freshen up the 361.
    Sell the 400 (I've heard that some use that block to build stroker motors).
     
  25. 270dodge
    Joined: Feb 11, 2012
    Posts: 742

    270dodge
    Member
    from Ohio

    Uh, I'm working from memory here but I think that if the 400's casting number ends in 630 it's a good one and of value. If it ends in 230 way better!
     

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