First stoker build

[SilverXJ]

No reason to change a 0630 for a 7120. Never heard of either having cracking issues.

[jcori3]

Is a 7120 a better head performance wise since i have to replace mine? Will it interchange with no modification?

[Cheromaniac]

Great, its the only way it made sense to me. Also having to get a new head. I read that a 7120 head will fit my 97 block with no modification, is this true?
I was told that the 0630 heads crack easier than the 7120 so that is the reason i was wanting to go with the 7120 head. Also heard that out of all the heads the 7120 flows better than the others. Also a thing i liked about the 7120. Is all this correct?

The only real difference between the 7120 head and the 0630 is that the earlier head has a threaded port at the back for the coolant temp. gauge sending unit. Either head would be fine for you.

[rammit11]

strange as it may seem the 6320 on the donor engine i used was cracked if I remember correctly between 1 and 2. I just think however the engine was pretty much abused and overheated severly as my current engine has the 6320 on and the replacement i got at the yard was fine also.

[SilverXJ]

0630

[jcori3]

putting my valve cover on and it wont go all the way down. there are two rocker arm bridges that have a little threaded post coming up about a inch. what cylinders do these go on. i had put them on the first and last but valve cover wont clear. thanks. I took both of the threaded bridges off and valve cover goes on just fine.

[jcori3]

But i need to whow which cylinders they go on so the rockers wont fly off. thanks

[SilverXJ]

We found that these were from a 4.2L and the machine shop just got his parts mixed up. Not from a 4.0L.

[jcori3]

Got my motor in and its running good. Cranks right up and good response. I am throwing some codes. 11,12, and 55. This is on a 97 tj. Anyone have any ideas?

[Cheromaniac]

Codes 12 and 55 are normal. Code 11 indicates a problem with either the CPS or the cam position sensor.

[jcori3]

You are right on the codes. So i went and got a new cam sensor and took my old one off and when i went to test drive with the new one my motor started misfiring and popping and would hardly run when i reached 1500 to 2000 rpm. i reset the computer and the code 11 came right back. So the next morning i got up and installed my old one and test drove it and jeep runs fine except i still get the code 11. So i went to autozone and got a new crank sensor and put it on. Reset the computer and it runs ok except the idle drops down and then comes back up when i get off the gas. It is a standard. But light came right back on and it was the code 11 again. So im kinda stumped. The motor runs great good power, runs and idles smooth doesnt miss or anything but i got to get it inspected so i got to fix that check engine light. I have heard that those two sesors you have to buy at the dealership cause aftermarket ones dont jive with the jeeps pcm. I am at a loss to what to do next. Any ideas?

[Cheromaniac]

I have heard that those two sesors you have to buy at the dealership cause aftermarket ones dont jive with the jeeps pcm.

I think it's more a case of some aftermarket sensors being of poor quality, and it's not unheard of for a small number of new sensors to be complete duds right out of the box.

[jcori3]

Any for sure way to figure out which sensor it is since the code says it could be either or?

[Cheromaniac]

Unfortunately not but from the symptoms you've described it's more likely to be the cam position sensor.

[jcori3]

went and got a autozone crank sensor and intalled it. Light stays on and after a day it left me stranded. Fortunately i had the old one in the jeep and the tools to replace it where i was broke down. Put the old one back in and fired right up and runs fine. Took that one back and got my money back. Also the only thing i can see as far as the running of the motor is when i put the clutch in sometimes the rpms drop real low like it is gonna die and then goes right back up to normal. Is this more of a cam or crank sensor? The dealership wants to rape me for the two sensors but i found a place online to get mopar sensors at a decent price. Any ideas on the rpms dropping down like that when i go to stop? Thanks