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Why do I read about so many 4.3 spun bearings??

Discussion in '1994-2004 V6 Mustang Tech' started by 2003/2013, Jun 21, 2017.

  1. 2003/2013

    2003/2013 Member

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    is there some weakness with the bottom end???

    Thanks!
     
  2. 6 Shooter

    6 Shooter Well-Known Member

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    Nope. The key is to not reuse the factory bolts which are stretch fit. Bite the bullet and go with ARP bolts, or factory brand new rod and main bolts each time. The other issue is precise rod and main bolt bearing clearances which should be 0.0015" on both the mains and the rod bearings, then switch to 5W20 weight oil. Will say that about only a machinist should build the bottom end to get the rod and main bolt clearances needed. Torquing the bolts is also critical. The rest can be done by handy hobbyists or any good auto mechanic.
     
  3. Lonnie-S

    Lonnie-S Member

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    This seems like a good opportunity to ask about the 4.2 crank, and what it fits into.

    I know the 4.2L crank was in the F150. Which blocks will it fit into and what must be done to make it work?

    I have a '97 Mustang 3.8 with a known history, and a 2000 Mustang 3.8 with a sketchy history, that I bought primarily for the top end (heads, intakes, throttle body, fuel rail, etc.). I'd much rather use the '97 block, bore it over 0.030", transfer the split port top end to it, and then use a 4.2L crank in the bottom end. Is that a workable strategy?

    Cheers,
     
  4. 6 Shooter

    6 Shooter Well-Known Member

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    Yes, but the 4.2L crank requires different short skirt pistions. Best to call Tom at Super 6 Motorsports and he will be able to tell you exactly which mix and match parts will work on the '97.
     
  5. Lonnie-S

    Lonnie-S Member

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    @6_Shooter

    Thank you, sir.

    Cheers,