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4.2 with 3.8 crank

Posted: December 17th, 2024, 11:03 am
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

Re: 4.2 with 3.8 crank

Posted: December 19th, 2024, 11:38 pm
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".

Re: 4.2 with 3.8 crank

Posted: December 20th, 2024, 8:08 pm
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!

Re: 4.2 with 3.8 crank

Posted: December 22nd, 2024, 4:00 am
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.

Re: 4.2 with 3.8 crank

Posted: December 22nd, 2024, 4:07 am
by Plaisanced
IMG_3562.jpeg

Re: 4.2 with 3.8 crank

Posted: December 22nd, 2024, 10:58 pm
by Cheromaniac
Unbelievable!