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General Forums => The Mess Hall => Topic started by: sbeltinc on September 12, 2006, 09:16:21 AM

Title: 2.5 interchangeability, CJ block in a TJ
Post by: sbeltinc on September 12, 2006, 09:16:21 AM
I have a 99 TJ (2.5) with a bad short block, will a short block from a 85 CJ (2.5) interchange?. Have found one locally for cheap.
I'd keep my MPFI head and all accessories so basically I'm wondering if changes where made to the block to prevent a direct swap into my TJ?
I understand the CJ fuel pump was mechanical whereas my TJ is electric, not sure if this is a problem.  

Thks
Scott
Title: 2.5 interchangeability, CJ block in a TJ
Post by: Jeffy on September 12, 2006, 11:32:55 AM
I believe it should work as long as you're using the block only.  You might have to fab up a cover plate for the fuel pump.  Although, I can't see how a YJ/XJ/MJ or even a TJ block couldn't be found.  The CJ block will no doudt have many miles on it.  Probably rust too if it's been sitting.
Title: 2.5 interchangeability, CJ block in a TJ
Post by: sbeltinc on September 12, 2006, 03:20:11 PM
Thks, considering the CJ shortblock since it's cheap and I'm only looking to make the rig mobile for a few months while gathering the necessary bits for a more adventurous swap.

Anyone else have experience with the differences between the 2.5 blocks?
Title: 2.5 interchangeability, CJ block in a TJ
Post by: dunklervogel on September 12, 2006, 09:25:08 PM
Well from all I've read the blocks should be the same.  I know over the years (84-02) some external stuff was shifted around and changed but the block itself should be the same I'd say.  Only problem I could see would be like bolt patterns for the exhaust manifold or something else eternal like that.
Title: 2.5 interchangeability, CJ block in a TJ
Post by: Jeffy on September 12, 2006, 11:03:54 PM
All the ports and studs should line up but like I said, I'd probably get a newer core.  Rust, broken thread holes and just general age could mean the block is toast and would need a bore job.