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post #1 of (permalink) Old 01-19-2004, 08:33 AM
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Couple of questions about my YJ

Hi all, this is my second post on these boards. I just bought a 87 yj that needs some work and i had hoped you guys/girls can help. needs a new muffler. do i buy a cheap cruddy muffler, or do i go all out and get a borola or something nice? Is the price of the borola worth the performance? Second....I'm runnin 35's so I want to increase the horsepower of the wimpy but sturdy 4.2L engine. What are some cheap ways you can do that? Lastly... i think i need to replace the carborator. Do I buy a used stock one for $40, or get an aftermarket upgrade. I hear the stock ones can have problems at higher grades but I do mostly mud and trail adventures, not alot of hard climbing. Thank you in advance for answering any or all of the questions!! See ya on the trails!
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post #2 of (permalink) Old 01-19-2004, 09:48 AM
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Re: Couple of questions about my YJ

Hi. Thanks for stopping buy. There are a lot of things you can do to your Jeep to make it better, but please go here first. Thanks.
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post #3 of (permalink) Old 01-19-2004, 11:33 AM
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Re: Couple of questions about my YJ

Big87YJ, Couple of things first, Please fill out your profile, atleast the basics, it's nice to know who we are talking to. Second, do a search on each item, most have been covered ad nauseum...with that said, here are my suggestions.

I put a Borla on. NO power gain as I could notice, but does give it a good sound and it will never rust...

The 4.2 is a good motor, lots of botom end but not a lot of top end, to help it simply run better, ditch the Carter BBL carb, Nutter it (do a search) and put on a Motorcraft 2100 carb. This is the cheapest reliable route. On the other end of the scale, Get the Mopar MPI (~$2300) easy to install, everything fits, and your Jeep will always start. With the MPI you will also get some power gains, but not a lot.

The 4.2 will run forever if you take care of it, but it's not gonna win alot of's a draft horse not a quarter horse :-)
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post #4 of (permalink) Old 01-19-2004, 01:01 PM
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Re: Couple of questions about my YJ

What gears are you running? If you are pushing around 35" tires with stock gears, that is where most of your power is going. The 4.2 should be able to push 35" tires, as long as they are geared correctly. You will never beat a Neon off the line, but you should be able to drive it comfortably. I believe you should be at a minimum of 4.10's, but most will tell you 4.56.
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post #5 of (permalink) Old 01-19-2004, 02:26 PM
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Re: Couple of questions about my YJ

Yep Like was said do the profile thing let us know who and where you are and what you have.

I also have an 87

What tranny do you have? Has there been any mods made to the Jeep by the PO?

If not you more than likely have the BA/5 tranny, (sad sad, real sad) commonly refered to as the "please go". your t case may or may not be the NP207, this too is a weak x-case. The fix there is to get a NP231 to replace it. You will also have the 30/35 axle set up front and rear, although you do not have the "c" clip axle the axles will not last long pushing 35's,,, lol,, or so I have been told by various people and I see them all the time out here running happily around.

For the exhaust get rid of the stock setup and replace it with a good Midas built or Borla if you have the money 2.5" exhaust system that will give you more power than any other mod.

410 geraing will get you back to near stock power output for the motor with the 35" tires but 4;56 will put you on the top side of the power output band.

You will get to know your clutch slave cylinder/throw out bearing very well when that system breaks down, and it will.

All in all the 87 was a cross over year for the CJ/YJ getting the better YJ frame and body but keeping the better starter, non clip rearend. It also got a lot of the XJ stuff that was not so good like the NP207 and vacuum disconnect front axle.
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