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History Mopar engine with a Chevrolet rotating assembly??

Discussion in 'The Hokey Ass Message Board' started by FRANK GRELLE, Mar 2, 2023.

    Joined: Oct 15, 2018
    Posts: 127


    I may be crazy but i remember a year or so ago a guy on a you tube channel was talking old school racing and mentioned how some race engine builder (if i remember correctly ) took a 327 Chevy crank. pistons, rods and put them in a 340 Mopar, With some machine work. Kinda sounded like some Smoky Yunick B.S. to me . What had me thinking about it was I was talking to my brother and stoker moters came up and I mentioned this to him ,and we goggled it and found nothing so I figured i would ask here were there are people wiser then I, What you guys know?
  2. lemondana
    Joined: Feb 21, 2009
    Posts: 204

    from Lincoln NE

    Why? The Mopar 340 is perfectly good with Mopar parts. Remember the 340 was a performance engine only-no 2 bbl engines, unlike the 327.
  3. TA DAD
    Joined: Mar 2, 2014
    Posts: 952

    TA DAD
    from NC

    Never heard of using the crank , but running Chevy rods is a common in a small block Chrysler is common.
  4. BamaMav
    Joined: Jun 19, 2011
    Posts: 6,228

    from Berry, AL

    Heard of using other make bearings and rods and even pistons in different engines before, now this is the first I’ve heard of using a different crankshaft, but I guess with a good machinist a lot of things are possible I’ve thought about. Don’t always understand the whys and why nots of using other stuff, but guess it all goes back to experimenting to get to a conceived result.
    FRANK GRELLE and Deuces like this.

    Joined: Nov 22, 2005
    Posts: 8,310

    from SIDNEY, NY

    That makes no sense. A 327 crank has a .060 shorter stroke, and the pistons have a .040 smaller bore.
    hemihotrod66 likes this.
  6. Deuces
    Joined: Nov 3, 2009
    Posts: 22,772


    Longer connecting rods maybe???....
  7. Why would anyone use SBC rods in a SBM,,,,,,what would possibly be gained .
    The Chevy rod is 5.7,,,,center to center,,,,,the Mopar is 6.123 ,,,,center to center .

    And I’m pretty certain that a Chevy crank can’t be adapted to a Mopar block .

    It’s amazing how stories are told and they become convoluted over the years .

    Now,,,,,,,many guys used to adapt transmissions and other things,,,,,,but that’s hardly a crankshaft .
    In very high torque situations,,,,,with a big slick,,,,,,the Mopar A833 was used in sone Chevies because of the stronger gears and iron case .
    The Muncie was a great transmission,,,,,, but the aluminum case was a weak link after a while in service .
    They have corrected those problems now,,,,,,but that was 50 years ago when the only choice was to adapt something .

    lemondana likes this.
  8. TA DAD
    Joined: Mar 2, 2014
    Posts: 952

    TA DAD
    from NC

    If memory serves me correctly, they used a 6.125 in rod with a custom piston and it was done to get a smaller bearing diameter. But that was like in the early 80's.
  9. Jmountainjr
    Joined: Dec 29, 2006
    Posts: 1,531


    Back in the 70's and 80's a lot of cross swapping parts was common. Olds diesel rods in SBC, cutting crank main bearings down to smaller size or using spacers to fit different blocks, cutting SBC crank rod bearings to Honda size, etc. was common. That was before Scat, Eagle, etc. came to market with so many parts to make it easier to accomplish the same thing.
    Deuces and Okie Pete like this.
  10. alphabet soup
    Joined: Jan 8, 2011
    Posts: 1,957

    alphabet soup

    I think TA DAD is correct. Chevy long rod, offset grind the crank to SBC journal diameter for added stroke. Gene.
    seb fontana, Deuces and razoo lew like this.
  11. PackardV8
    Joined: Jun 7, 2007
    Posts: 1,007


    Back in the bad old days, the knowledgeable SBC racers threw away the 3" or 3.25" Chevy crank and machined a Studebaker 289" V8 crank to fit the SBC main bores and gain a 3.625" forged steel stroker.

    jack vines
  12. Mr48chev
    Joined: Dec 28, 2007
    Posts: 32,629


    I'd say that your correct answer is right there. Racers were looking for the combination that got a certain displacement and a good bore/stroke rato for cars that had to run engines with said displacement to fit in a class. That more often than not was circle track racing. If the factory didn't provide a combination that would work to get your engine of choice in that displacement class or just as critical the aftermarket at the time didn't provide rods or other pieces that would work. You sat down with the shop manuals with the specs pages open and you had the engine parts catalogs next to them on the table and you started figuring out what might work and how much your machinist was going to fuss when you asked them to do somethign a bit out of the norm. In some area it was also about $$ tied up in the engine as there were limits and a lot of tracks rain claimer races where someone could claim your engine For X $$. That kept the high rollers from having 10 K engines running in a 1500 dollar engine class.
  13. I doubt that anyone put an SBC rotating assembly in a 340 MOPAR.
    the bore spacing on a small block MOPAR is 4.460. The bore spacing on a Small Block Chevy is 4.840. That is .380 difference. 3/8" is .375. 3/8" is a lot to overcome.

    Someone may have used Chevy rods in a MOPAR but custom rods are so cheap now that there is no reason to do it.
  14. Speed Gems
    Joined: Jul 17, 2012
    Posts: 5,810

    Speed Gems

  15. gsjohnny
    Joined: Nov 27, 2007
    Posts: 215


    my 350 buick uses a modified mopar 340 intake, chevy valves, honda rod bearings, roush nascar con rods, 283 forged pistons and a modified ford ati balancer. 6-71 on top. going to go to 8-71 just because.
    that's called r&d. lol
    alanp561 likes this.
  16. Kevin Ardinger
    Joined: Aug 31, 2019
    Posts: 639

    Kevin Ardinger

    If your brother googled it and nothing came up then that’s that. Right? Google is great for most things but not everything.
  17. X-cpe
    Joined: Mar 9, 2018
    Posts: 1,732


    My references say:
    Mopar - 4.460
    BBC - 4.840
    SBC - 4.400
    Still 0.060, or almost 1/16".
    Hnstray and Deuces like this.
  18. You may be correct, I looked at an old notebook and if I grabbed the wrong one I could have referenced BBC. :oops: still .060 is a lot to overcome. .030 per side of rod journal not taking into account of the main journal spacing and block length. Won't say it cannot be done, will say that it is a Don Quixote adventure.
  19. gene-koning
    Joined: Oct 28, 2016
    Posts: 3,443


    I think someone had a love affair with a 327 and a hate relationship with a 340 and held a grudge. :D

    Lots of internal motor parts were swapped from one brand into others back in the 70s & 80s.
    In the early 70s Mopar ran in the Trans Am Racing Series, the motors were limited to 305 CI (or something close). That was a cubic inch displacement no combination of Mopar motor parts could create, but the motor had to match the body, so the boys came up with a combination of parts to get the job done. If those parts were specially made, or came off someone else's parts shelves may never be known. Of course, those parts suddenly had Mopar part numbers on them and were available through their Direct Connection program. Where ever those special parts came from, they must have worked pretty well. The Dodge boys did pretty good for beginners in an established series.
    lemondana and Desoto291Hemi like this.
  20. Kerrynzl
    Joined: Jun 20, 2010
    Posts: 2,589


    I betcha the damn thing ran so hard you couldn't grab the $100 note stuck on the dash
    X-cpe likes this.
  21. indyjps
    Joined: Feb 21, 2007
    Posts: 5,349


    Let's get a list going, I've heard of most of these, what else is out there. Most require you have personal access to a machine shop, and we're created when there weren't aftermarket options.

    Oldsmobile 6" rods in sbc, both ends of rod need reworked, for off shelf sbc 6" rod pistons.

    Chevy SBC or BBC rods in any combo, take advantage of lower cost aftermarket rods.

    Chevy 5.94" powdered metal rods from 4.3L (L99) b-body V8's of the mid to late 90's. Weird little engine, and medium duty long rod, sounds good, ends up with more machine work than it's worth.

    Honda bearing size, mainly nascar but has trickled down - smaller rod and main for long duration high rpm.

    Studebaker crank in SBC, first I've heard of it, very cool.
    Last edited: Mar 5, 2023
  22. indyjps
    Joined: Feb 21, 2007
    Posts: 5,349


    Mid 90's, I had a set of Olds rods that had been reworked for a sbc, bushed pin and resized main. Along with 6 JE forged 4.030 pistons. Was looking for the other 2 pistons. Bought at circle track swap meet. At the time I'd buy used partial sets of JE or TRW forged, lotta circle track used the same spec rotating assy.
    Never built that Olds rod combo, don't even recall what happened to the rods....they may still be somewhere in the shop.
  23. It’s wasn’t odd to see Chrysler rods in a ford
    That cubic inch is off. Pic from another forum. small block dodge rods was used. I think I remember a 408 or something like that from using them
    alphabet soup likes this.
    Joined: Oct 15, 2018
    Posts: 127


    LOL ...did you name it Frankenstein?
    X-cpe and anthony myrick like this.
  25. gimpyshotrods
    Joined: May 20, 2009
    Posts: 22,618


    My blown Chrysler 354 has BBC rods.

    It may come as a shock to some, but connecting rods can be located on the rod journal by the piston pin, with way more room on the journal than old-school folks would ever consider acceptable.

    Modern NASCAR stuff comes to mind.
  26. sunbeam
    Joined: Oct 22, 2010
    Posts: 6,032


    hemihotrod66 likes this.
  27. gimpyshotrods
    Joined: May 20, 2009
    Posts: 22,618


  28. Speed Gems
    Joined: Jul 17, 2012
    Posts: 5,810

    Speed Gems

    Ford I 6 rods in a 400 SBC.
    I also seem to recall reading an old HOT ROD magazine article where they used Cadillac rods in a 392 hemi.
    Last edited: Mar 7, 2023
    indyjps likes this.
  29. gimpyshotrods
    Joined: May 20, 2009
    Posts: 22,618


    Now we put Honda rods in the Ford inline-6.
    Speed Gems likes this.
  30. cabong
    Joined: Nov 29, 2005
    Posts: 816


    Ak Miller used a 292 Y-Block crank to stroke his 260 Ford that he used in one of his first Devins at Pikes peak. Ran like stink and he won the sports class. Ray Brock told me it sounded like no other V8....

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