4.2 with 3.8 crank

Performance mods and Advanced Stroker discussion.
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Plaisanced
Posts: 3
Joined: December 17th, 2024, 10:59 am
Stroker Displacement: 4.8
Vehicle Year: 1979
Vehicle Make: Jeep
Vehicle Model: Cj7

4.2 with 3.8 crank

Post by Plaisanced »

Pulled my engine apart and was shocked it has 4.0 length rods and 3.8 crank it’s bored .030 what would the reason to put this combination together. The root cause of tear down was #2 cylinder had a diffrent sound and it had a 4.2 rod so a good 3/8inch below head deck
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Cheromaniac
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Re: 4.2 with 3.8 crank

Post by Cheromaniac »

Evidently someone attempted to build a 4.1L mini-stroker (4121cc to be exact) using the 232 crankshaft, except that they should have used 4.0L rods in all of the cylinders with pistons that have a compression height of ~1.58".
1992 XJ 4.6 I6 - 5MT - Stroker build-up, Stroker "recipes" Sold
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dwg86
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Re: 4.2 with 3.8 crank

Post by dwg86 »

Plaisanced wrote: December 17th, 2024, 11:03 am Pulled my engine apart and was shocked it has 4.0 length rods and 3.8 crank it’s bored .030 what would the reason to put this combination together. The root cause of tear down was #2 cylinder had a diffrent sound and it had a 4.2 rod so a good 3/8inch below head deck
good gosh! How does someone screw up that bad...sheez!
Plaisanced
Posts: 3
Joined: December 17th, 2024, 10:59 am
Stroker Displacement: 4.8
Vehicle Year: 1979
Vehicle Make: Jeep
Vehicle Model: Cj7

Re: 4.2 with 3.8 crank

Post by Plaisanced »

I think the previous owner purchased a 4.2 rod after possibly bending one the jeep was used as a mud bog racer and motor sucked in water so they just ordered a 4.2 rod for it and never paid attention to casting numbers on it.
Plaisanced
Posts: 3
Joined: December 17th, 2024, 10:59 am
Stroker Displacement: 4.8
Vehicle Year: 1979
Vehicle Make: Jeep
Vehicle Model: Cj7

Re: 4.2 with 3.8 crank

Post by Plaisanced »

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Cheromaniac
I live here
I live here
Posts: 3258
Joined: March 8th, 2008, 12:58 pm
Stroker Displacement: 4563cc
Vehicle Year: 1992
Vehicle Make: Jeep
Vehicle Model: Cherokee
Location: Cyprus
Contact:

Re: 4.2 with 3.8 crank

Post by Cheromaniac »

Unbelievable!
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