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  1. gearhead

    gearhead Well-Known Member

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    I've inherited an '87 Wrangler. It originally had a 2.5l engine. It's had an engine swap and now has a 6cyl.
    1- How can I tell whether the engine is a 4.2l or a 4.0l?
    There is no mechanical fuel pump boss on the block, but from what I can determine the 4.2 was available with F.I. for a couple of years and didn't have the boss in those years.
    The intake manifold looks like an OEM aluminum 2bbl manifold. Both bores are the same size. There is a circular electric heating element in the bottom of the manifold held in with 3 bolts. A Carter 2bbl for a 273/318 fits on it perfectly, It had a Motorcraft progressive 2bbl on it, but the mounting bolt holes were totally buggered to make it fit. The exhaust "manifold" is a tubular header style with round ports and looks OEM.
    Any ideas on exactly what I might have? Thanks.
     
  2. ImperialCrown

    Level III Supporter

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    Engine #? It should be stamped into a boss on the passenger side of the engine.
     
  3. gearhead

    gearhead Well-Known Member

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    312MXI7
    I'm pretty sure it's at least got a 4.0 head on it since I bought a 4.0 intake/exhaust gasket for it today and it fits.
    This is the other one of the unfinished father/son projects that I've decided to complete, but this one doesn't need any bodywork. LOL!
     
  4. ImperialCrown

    Level III Supporter

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  5. gearhead

    gearhead Well-Known Member

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    I'm almost positive it's a mongrel. LOL! I have noticed on a couple of Jeep forums I've browsed that the 4.0 swap for pre '90 Jeeps is relatively common, and that it usually involves using the 4.2l intake manifold. I think by now I'm pretty certain I've got a 4.0 (and not a 4.2 with a 4.0 head on it, which is also a popular "upgrade") since there's no provision for a mechanical fuel pump on the block.
     

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