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Discussion Starter · #1 ·
Looking for some advice on which carb will work best on my 87 YJ 4.2. Was considering Weber K551-38. YJ has a fresh rebuilt motor- balanced, shaved head, slightly larger cam. I have also done away with ALL emissons crap, and done the nutter bypass. YJ still not running well. I'm hoping that a new carb will help. I've heard that the Weber carb with a fuel pressure regulator is a good way to go, but not talked with anyone who has done it. Also considering HEI upgrade. Any suggestions would be appreciated.
 

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I run a weber 32/36, and a GM HEI on my 88YJ, and have for many years now. I think it's a great combo, and has worked well for me for a long time.

However, you will likely find that most people here will tell you that a rebuilt Motorcraft 2100 carb, with a TFI system is the best bang for the buck.

Do a search on "MC2100", "TFI" and "HEI", and you will likely find more info than you would ever have time to read.

Good luck
Pete
 

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Both of these topics have been discussed within the last couple of weeks. /ubbthreads/images/graemlins/smile.gif
 
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Discussion Starter · #4 ·
And until you put some of the emissions 'crap' back on, don't expect it to run to well.....

There are a few mods that work...but overall, trying to re-engineer the engines is a loosing battle...if you really want better performance, go fuel injection...like the Howell or Mopar system.
 

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I've had very good results with the MC2100, a remote mounted HEI module driving a TFI or HEI coil (ignition resistor eliminated.)
The distributor easily converts with the adapter to the big cap and rotor, and use the 8MM plug wires.
Disable the EGR vacuum line.
Run the distributor vacuum on ported vacuum, not manifold vacuum.
Use the original equipped plugs but gap them a little wider - .040's fine.

You'll love the difference - lots more power, better mileage, and less emissions.

The MC 2100 is simple, easy to fix, cheap and plentiful. You just need the adapter.

I've done about 15 of them now.
 
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Discussion Starter · #6 ·
Thanks for all the info. I'm going to look into the fuel injection kits for my YJ. When I started this project I was a little over my head when it comes to the engine replacement and the guy that was helping me, who says he has worked on many jeeps told me I didn't need all that emissions crap so we took it out and threw it ALL away. Needless to say now the YJ runs like crap. The nutter bypass did help some.
 

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I guess I may fall on the 'minimalist' side of the emissions argument.

Most of my emissions crap is gone - the pulse air system, solenoids, etc.

I do run a catalytic converter, and I do run an EGR valve. My YJ passes emissions on the dyno in Massachusetts, where you have to run 3 times, up to about 35 MPH, and back to idle. She runs clean, and runs well.

Just my $0.02 on emissions.
Good luck
Pete
 

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I agree... any engine can run well and clean with emmisions equipment removed. IMHO a non-computer controlled emmision clogged engine may be easier to get to pass simply because there are easier to work on and tweak without setting off bells and whistles and effecting other emmisions components.

You may want to go back through your nutter bypass procedure just to double check your work.
 
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