1985 jeep cj 4.2 swapping in 1990 4.2 from yj

[pooch59]

Hello, I'm new to this jeep forum and I have a project 1985 cj7 that is in good shape. I just purchased a 1990 yj 4.2motor I want to swap it out but noticed the motor mounts are different. The 3 bolt pattern is reversed 2.bolt down 1 on top for the 1985 and the 1990 is 1 bolt down and 2 bolt on the mount plate. Other than the mounts what else would be needed for this swap to happen? I want to use the 1985 manifolds.

 

[superj]

Valve cover bolt pattern might be different also. Other then that, put it in

 

[pooch59]

On the cj7 frame the motor mounts are different from the yj 1990 motor, is there a vendor that sells motor mounts for 1990 4.2 to 1985 cj7 frame or do you have to fabricate one yourself?

 

[PoliceMonkey161]

The motor mounts are different on the YJ to accommodate the larger oil filter that was used by Chrysler. AMC 's design had an internal to the block oil bypass and drain back valve, the Chrysler re-design was external and inside the filter. Unfortunately, the two different era blocks can't interchange these oil system parts, so you'll need to modify the CJ frame for the YJ mounts ( fairly easy to do).