Spooledwhat

i just bought an 87 cherokee with a 7in lift and built for beating the crap out of, ill get pics soon. we got it running and it idles really high untill it heats up which im not worried about. what im worried about it that within 5 min of driving it went from good temp to beyond 330 degrees. which im sure its the thermostat?? but befor that i had it to the floor and it would get to 45 mph and the rpms would be dead and it wouldnt go any faster.. would this be something with the motor or the tranny? and i think it needs a new throttal body or carb, dont even know what it has. but any help would be awsome.

solderjunkie

You have several issues.

A new throttle body won't fix anything.

Fix the overheating problem first (since it will destroy the engine). Get it up to temperature, then see if the fan is pulling hot air from the radiator... this tests three things: thermostat-opening, fan clutch, and water pump.

XJ Stryker

You could have some cooling issue you need to inspect the entire cooling system including water pump.

7 inches of lift so what size tires does it have. What are the axles if you got 35's on 3.55 gear ratio I would be surprised if you could get to 45 lol. Bad thing about buying someone else's project rig is you never know what they did with it.

BuckB91XJ

Fix your cooling problem first. Most likely a T-stat but, since this rig was already lifted and has seen off road thumping. It could be leaking out out of anywhere or it could just be straight up clogged with corroded crap. Check for leaks. Give it a new T-stat and flush the cooling system out really good.
Your not being able to get it over 45 with the pedal mashed could definitely be a result of a BIG tire and gear mismatch. If it's a problem of the engine not going over a certain rpm, that is mostlikely a fuel pressure or ignition timing problem.

Spooledwhat

yeah stryker it only had 33 12.5s on it and there the same tires i have on my white jeep and i have stock gears from a manual so its like 3.05 i think. the kid said he put new gears in it but like what you said who really knows cause its wasnt my project jeep. and im buying it for a grand and it has 6 brand new 33 12.5 mud kings on rims, SYE and upgaded everything else .but im thinking about just taking the whole underside of the jeep seeing how its built for rock crawling and mudding and swapping it out on mine and maybe scrapping out the rest but im not sure yet. but ill be trying to get it running and ill let you know how it goes.