TheDirtyJeep401 Posted November 6, 2023 Share Posted November 6, 2023 Well, after running a compression test. Turns out the original 2.5 is worn out. Worse than I originally anticipated. I have a few 2.5s laying around but have few questions. I have an 92 2.5 sitting on an engine stand. From what I have found, all 2.5 blocks are the same. I know there is a slight variation in the heads over the years, but still work on a TBI motor. The big question I have is the cam. The TBI models from what I’ve seen have a slightly bigger cam than the MPFI models. So with that, does the MPFI cam work fine in a 86 TBI? Or does it need swapped over? Are there any other variations that would need swapped over other than the normal stuff (Intake,flywheel,sensors,etc..)? Link to comment Share on other sites More sharing options...
eaglescout526 Posted November 6, 2023 Share Posted November 6, 2023 Flywheel you will need to swap. I don't know a lot about the HO year motors but I can’t imagine any issues with swapping a while HO motor to be with a Renix set up. Link to comment Share on other sites More sharing options...
cruiser54 Posted November 6, 2023 Share Posted November 6, 2023 Early 2.46s had a manual fuel pump on the block. That can be blocked off. Your engine won't care which injection system you have or which cam you use. Link to comment Share on other sites More sharing options...
TheDirtyJeep401 Posted November 13, 2023 Author Share Posted November 13, 2023 On 11/6/2023 at 5:53 AM, cruiser54 said: Early 2.46s had a manual fuel pump on the block. That can be blocked off. Your engine won't care which injection system you have or which cam you use. On 11/5/2023 at 8:17 PM, eaglescout526 said: Flywheel you will need to swap. I don't know a lot about the HO year motors but I can’t imagine any issues with swapping a while HO motor to be with a Renix set up. What about water pumps? It’s been a while since I put one in on the 86. I started tearing down the 92 and noticed that it has a reverse water pump. Did all of them have reverse rotation? Or is it something that they did on the 91+ motors? I can’t remember for the life of me on if the 86 was reverse or not. Link to comment Share on other sites More sharing options...
eaglescout526 Posted November 13, 2023 Share Posted November 13, 2023 84-86 had both V-belts and serps as an option. 87-01 was just serp so it really is more on the belt set up than anything else for the rotation of the pump. Link to comment Share on other sites More sharing options...
GrandBoost98 Posted November 13, 2023 Share Posted November 13, 2023 9 hours ago, eaglescout526 said: 87-01 was just serp FWIW, I have an 89 with vbelts Link to comment Share on other sites More sharing options...
cruiser54 Posted November 13, 2023 Share Posted November 13, 2023 Okay, so here's what we have. Any 2.46 will work in a fuel injected application. You MIGHT have to install a fuel pump block off plate. You need to be aware of which water pump your MJ uses based on the belt drive. v-belt or serpentine. Link to comment Share on other sites More sharing options...
eaglescout526 Posted November 13, 2023 Share Posted November 13, 2023 3 hours ago, GrandBoost98 said: FWIW, I have an 89 with vbelts WTF?! Link to comment Share on other sites More sharing options...
acfortier Posted November 13, 2023 Share Posted November 13, 2023 3 hours ago, GrandBoost98 said: FWIW, I have an 89 with vbelts Are you referring to your Wrangler? Link to comment Share on other sites More sharing options...
eaglescout526 Posted November 13, 2023 Share Posted November 13, 2023 I can see the 4.2L having V-belts in the YJ but not so much the 2.5L either. Link to comment Share on other sites More sharing options...
GrandBoost98 Posted November 13, 2023 Share Posted November 13, 2023 Yes, I'm referring to my 89 YJ motor. eaglescout said 87-01 was serpentine, so I was assuming he was referring to any jeep 2.5L Link to comment Share on other sites More sharing options...
eaglescout526 Posted November 13, 2023 Share Posted November 13, 2023 Most of the YJs I have seen have had the 4.2L and if I saw a 2.5L, it was a serp set up. So that’s interesting that Chrysler would’ve kept using the V-belts for the YJ when every XJ and MJ had serp for the 2.5L. Link to comment Share on other sites More sharing options...
GrandBoost98 Posted November 13, 2023 Share Posted November 13, 2023 I believe YJ 2.5Ls switched to serp in 90' or 91' when they also switched from TBI to MPFI. Link to comment Share on other sites More sharing options...
eaglescout526 Posted November 13, 2023 Share Posted November 13, 2023 That’s a really weird anti saving money thing for Chrysler to do after they bought AMC. Link to comment Share on other sites More sharing options...
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