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post #1 of 5 Old 08-17-2011, 08:42 PM Thread Starter
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1987 YJ Wrangler 
Join Date: Jul 2009
Location: Downingtown
Posts: 869
Need some guidance

Alrighty fellow Jeepers, I need some advice or guidance. Within the past year my grandmother has passed and left the family with some money. My dad decided to give my sister and I each $1000 and then put the rest into savings. I've been struggling with the carburetor as of late and wonder if FI is my answer. Alright, here is the decision to be made. Do I use the money to install a FI onto my 4.2 or do I look around and swap in a 4.0L? Any other ideas are surely welcome. Thanks and hope you all can help me sway my decision.

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post #2 of 5 Old 08-18-2011, 08:00 AM
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1989 YJ Wrangler 
Join Date: Apr 2008
Location: Detroit
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Your 4.2L Is pretty much a 4.0L already. You can just get the intake and underhood electrical from a 91-95 4.0L and swap it over to get FI. It would be much cheaper too.
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post #3 of 5 Old 08-18-2011, 08:07 AM Thread Starter
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I like where your going with this? Is there special casting numbers for the intakes and such? I will have to do some research when I get a chance.
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post #4 of 5 Old 08-18-2011, 08:25 AM
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1990 YJ Wrangler 
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Location: colorado springs
Posts: 700
There is a very good thread on that swap. Some mods are needed for the power steering box and to the intake itself but looks easy enought.

Another option is a TBI from a gm. No mods (just adapter plate) but lots of wires which I think you have to do with the 4.0 intake also. (I went this way. Less labor but more thinking.)

You can also do the entire 4.0 head swap.

Warning: This poster has infinite knowledge of useless information and redneck tendencies. Use info at your own discretion. :wave:
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post #5 of 5 Old 08-18-2011, 08:56 AM
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1989 YJ Wrangler 
Join Date: Apr 2008
Location: Detroit
Posts: 24,680
There is no special numbers for castings. The intake from a 91-95 4.0L wrangler or Cherokee and all the wiring from under the hood because they are very similar. No Grands because the ECU and wiring are different. Everything is pretty much bolt on. The ECU needs a crank position sensor input and a Vehicle Speed sensor input. So you need a Flywheel from a FI or the Hesco cranks setup and a VSS that combines the mechanical cable with a electronic output like the 91YJ. Last is the fuel. The MPFI have a closed loop system with high pressure pump in the tank. You can get a used tank and pump setup for around $100(It gives you an extra 5 gallons) and replumb the gas or get an external one that is self regulating.

You can do it on the cheap and I think for under $500 be MPFI.

The head swap is something different and not needed for the MPFI. It suppose to give you an extra 40HP.
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