i have a 86 cj7 w/ a 4.2liter 258. i installed a holley 2 barrel 500cfm carb and eliminated the on board computer. the engine is bored .060 over w/ stock cam i also put on a single outlet in frame headman header. im not happy w/  the constant tunning the carb needs. i have thought about buying a holley pro jection kit or a weber 2 barrel 300 cfm . the jeep is used for off-road use only . any info will be helpful thanks.  

    From the info you gave at this point, that Holley carb. is a little on the large side for a 60 over 258-6 with a stock cam. This engine makes its best power under 2500 RPM. That 500cfm Holley is over-kill for your cam. Also the same goes for the header you installed on that head with its thumb-nail size ports on the exit side. This is not a 5000rpm small block V-8, and it never will be. If you plan on keeping this carb, you will have to match it to your cam, gearing torq. conv, if auto. trans. The weber carb would have been the better choice, or a Holley with a rating of 350 to 400 cfm, I would stay closer to the 350 side of this. Remember, again, these are high torq. low RPM engines!!! I have been in this same boat that you are sinking in right now. I diched any more ideas of finding the golden carb that will fix all of the problems you are having right now. The Webber works very well, but its still a carb, with drawbacks they all have. tuning for one. It will still cut out on a steep climb, sticky chokes, and on and on. At this time I am running the Howell Inc. E.F.I. in my 1990 YJ with the 258-6. This has worked the best to date. Its matched very nice to the stock cam torq curve, and pulls like a monster from 800 to 3200 RPM, best money I've spent to date on it. This is  also a stock cammed 60 over 258. Works in a word,"MINT". Everything you will need comes in the kit, but an air cleaner & housing, also will need a crankcase vent for the valve cover, and one 2 dollar panel light for check engine, and codes. Total cost to me was about $1150.00. Worth every penny! You may need your manifold heater in good working order if you live in a area with cold weather. The only other info on that 500cfm Holley that might help is to try and rejet the thing, size I don't know. all you can do is drop a size or 2 at a time and for GOD sake watch the plugs, and don't let it get too lean, witch can happen fast with a bigger cab and small jets !!!!! Also your timing should be set at 6 to 10 degrees BTD with the factory feed-back system unhooked, @800 RPM, vacum advance disco. & plugged. Remember too that 500cfm carb will feed a 400 plus c.i.d. engine all day and night with out any problems, it has no place on a 4.2liter inline six. the word of the day? "OVERKILL"!! Good luck with what ever you end up doing with it. Just do it as a package, and take in to account the whole powertrain and drive line. This adds up to more wheeling & less time under the hood!!!!  

i would go with a motorcraft 2100 carb or 2150.  their cheap and easy to find in a bone yard. you'll need an adapter plate from summit. its a small bore to a big bore. you can get the carb from and early 80s ford 302 or an amc 304. just a little modification to the throttle linkage and your good to go.