96lockednloaded

I've done some reading and I come up with the 7120 being a better flowing head more so if you port it. I have the 0630 head on my Jeep now but it's overheating and all signs are leading to a cracked head. The 7120 heads sitting on my bench so was gonna clean it up and throw it on. Anyone have any experience with swapping these heads, anything I should know besides the 7120 exhaust ports are a tad different. Any input is appreciated.

bluejeep2001

The 7120 heads have the hole for the coolant temp gauge sensor near the back of the head...drivers side depending on your year 0630 you might have that sensor or its plugged... The valve covers are different...the 7120 valve cover has a lip that will not match up to the 0630 untill its ground off flat...the 0630 valve cover has a flat bottom so it might sit correctly on the 7120...I liked the lip held everything from moving around...I thought the 0630 was a fairly robust head...they usually don't crack like the 0331..your overheat issue is probably not due to the head unless your pressurizing your water jacket and blowing the coolant out the overflow

96lockednloaded

Good to know about the valve cover never saw anything about that in my reading. I have the cover and everything for the 7120 head so that's no big deal. Ya this over heating has been killing me. I've check and tested everything. Just put a new head gasket in,thought that was my problem but still doing it. Some how I'm building pressure in the coolant system. Has new thermostat,head gasket,water pump, duel electric fans new radiator. Basically everything but the heads been replaced. I'm lost on this thing

Martlor13

What signs are being shown of a cracked head?

96lockednloaded

Multiple misfire, loosing coolant, pressure builds in the coolant system (exhaust pushing into it?). Pretty much entire coolant system been replaced minus the head.

Martlor13

have you done tests? Pressure test and block test?

96lockednloaded

I have pressure tested the coolant system and I loose pressure with the engine off. But if I have the motor running and put the pressure tester on I built almost 19 lbs of pressure in the coolant system.

Martlor13

Try a block test to see if you have exhaust gases coming in.

Nevic1

I have a 96 cherokee. Everywhere I read says it should have a 0630 on it but i pulled a cracked 0331 off of it. I want to put a 7120 head on it. I was wondering can i just bolt it up with no problems or do I need an adaptor plate? Please help