Installing a 4.2 crankshaft into a 4.0 block
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JT Ranch
- Posts: 3
- Joined: August 27th, 2019, 5:12 pm
- Vehicle Year: 1979
- Vehicle Make: jeep
- Vehicle Model: cj5
Installing a 4.2 crankshaft into a 4.0 block
Are modifications necessary? What about the snout length of the 4.2 crank??? The crankshaft is from a 1979 4.2 CJ5, Depending upon what's available, would like to put this 4.2 crankshaft into a 1991-98 4.0.
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Cheromaniac
- I live here

- Posts: 3290
- Joined: March 8th, 2008, 12:58 pm
- Stroker Displacement: 4563cc
- Vehicle Year: 1992
- Vehicle Make: Jeep
- Vehicle Model: Cherokee
- Location: Cyprus
Re: Installing a 4.2 crankshaft into a 4.0 block
You'll either need to shorten the crank snout by 10mm, or cut the rearmost 10mm from an old harmonic balancer and use that as a spacer in front of the new harmonic balancer.
1992 XJ 4.6 I6 Stroker - 5MT - 200rwhp 258rwtq - Sold
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JT Ranch
- Posts: 3
- Joined: August 27th, 2019, 5:12 pm
- Vehicle Year: 1979
- Vehicle Make: jeep
- Vehicle Model: cj5
Re: Installing a 4.2 crankshaft into a 4.0 block
Thank you, appreciate your comment!