1990 YJ engine swap. 2.5L to 4.3L - JeepForum.com
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post #1 of 4 Old 11-26-2013, 09:50 PM Thread Starter
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1990 YJ Wrangler 
Join Date: Feb 2013
Location: Conroe
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Yj 1990 YJ engine swap. 2.5L to 4.3L

Hey guys. I have a 1990 YJ 2.5 with the ax5 5 speed. No ac, no power steering. All stock. I have a 1999 Chevy Blazer with a 4.3 that I'd like to put in the jeep in place of the 2.5L. Going to be posting as I go through this project, and any support on this from people who have done it would be greatly appreciated. The blazer is a 2wd, so i will be getting a chevy t case this week (231c). Still trying to decide what to do as far as a trans... My grandfather owns a transmission shop, so i can get whatever, just havent decided what to go with yet.... Wanting to keep it a standard.. Dont know if the ax15 or NV3550 would be easier/better..... Opinions...???

Last edited by F3RG; 11-27-2013 at 09:18 PM.
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post #2 of 4 Old 12-05-2013, 04:50 PM
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1991 YJ Wrangler 
Join Date: Jun 2012
Location: Walcott
Posts: 4,504
4.3 is a solid motor, I have one in a 94 blazer, but man the FI system is a pain on these things. you will need to upgrade fuel pump, as they require alot of psi (iirc mine is 55, the newer one closer to 60) and most of the regulator and all that is inside the upper intake and has a tendancy to cause problems. Im not trying to steer ya away just sharing my experience with them, YMMV
as far as the tranny goes thats well over my head. just watch the overall length of the drivetrain

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post #3 of 4 Old 12-07-2013, 06:52 PM
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1978 CJ5 
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I'd skip the 3550 and ax15 and go with a chevy nv3500.

It's the same as the jeep nv3550 but with the bellhousing built into the transmission case and will bolt straight up the 4.3 or any chevy 4.6 or v8 engines.

The output I belive is a 32 spline that should bolt up to the 241c.

Also double check on the 241c as certain years may be drivers or passenger drop.
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post #4 of 4 Old 12-07-2013, 07:02 PM
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Originally Posted by UltimatE View Post
Max has a picture of every Jeep part ever made.
Originally Posted by Benderff View Post
No one here knows what they are talking about. You should try Pirate 4x4 they will be happy to help you.

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