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Discussion Starter · #1 ·
hey guys, so i got this 1990 trooper with the 4ze1 engine in it. it had a bad casting number 2 head in it. so i bought a new head from j and c heads, it has a 1 year warranty. so on so fourth. so my question is. can i run this engine without all the smog on it? will it run the same or run crappy? i live in oregon. so no smog regulations to worry about. i know my old 2.3 carbed engine didnt have any of the smog on it and it ran great. but it was also carby fed. so i want to get rid of all the smog junk. but im afraid ill get crapy results since its efi and has a oxygen senser and what not. anybody already done this? know the side effects and tricks? please let me know.

wil
 

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I just did a smog delete on mine and didn't notice any difference at all (some even say they get small improvements). It's a great way to clean up the engine bay but be careful what you use to plug the holes in the head. I stuck some spare spark plugs in mine because that's the only thing I could find in size m14 with a 1.25 pitch and it has a really annoying whistling now. Still hunting for something to plug it up that won't whistle so bad.
 

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You can pull it off with no issues. I pulled both of mine.
 

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Discussion Starter · #4 ·
Ok. So that's good to know that I can do it. So get rid of air pump. Cap off things for air pump. Wat about the oxygen censor? Do I have to keep that? And Wat about the reched tube going from the exhaust manifold to intake? Wats that thing good for? I kept it on my 86 but never got it to thred back into the exhaust manifold. Anything else I should know? Thanks guys.

Wil
 

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I just cut the tubes off the air tube in the manifold and welded them up and ground smooth. Looks like funny bolts now. Be sure and use the tubes and the nuts, as someone said these are 14 x 1.25 and NOT NPT . The tube bottoms out and does the sealing. Same thing on the EGR tube. My truck runs better with the converter on it than just a pipe.

Gotta have O2. Required for injection system to reference for mixture and timing calculations.

Billy
 

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Discussion Starter · #6 ·
so i got the new head, and i relized something. these heads arrent the same. the original head off the motor has round parts where the cylinder goes. the new head has heart shaped cylinder places. and the valvles are bigger on the new head. and it looks like it will have smaller cc chambers meaning higher compression, so the true question is will this new head clear the vavles from the pistons or are they gonna clash like the titans and screw everything up? please let me know if you know.
 

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86trooperman said:
so i got the new head, and i relized something. these heads arrent the same. the original head off the motor has round parts where the cylinder goes. the new head has heart shaped cylinder places. and the valvles are bigger on the new head. and it looks like it will have smaller cc chambers meaning higher compression, so the true question is will this new head clear the vavles from the pistons or are they gonna clash like the titans and screw everything up? please let me know if you know.
There are some folks on here who have done a lot of checking around regarding cylinder heads. psgaurdian is one of them and hopefully he will chime in. I *think* what you have is a later casting and if my memory serves me, you should be able to use it. In fact, I think it offers three advantages: 1) bigger valves, 2) smaller quench and 3) lack of AIR ports. Again, I hope someone with first hand knowledge & experience can chime in. I am just repeating what I recall having read here.

One piece of actual info that I can provide: The thread size for the EGR tube going into the Exhaust manifold is M22 x 1.5. I found a plug for this by searching napaonline.com for oil pan plugs of this size...

Here is another piece of real info, if your cylinder head does have the AIR tube holes, the oil drain plug from a 1984 2.5l Jeep Commanchee fits nicely. You have to remove the flange though. Some chock the plug up in a lathe and cut off the flange, but I just got creative with a drill and a die grinder...

On a related note, NPT pipe plugs "kinda" fit in the AIR tube holes and in the EGR hole on the exhaust manifold, but I found it better to use plugs above with the correct actual metric thread size. On the intake manifold side I did use NPT pipe plugs (1/8, 1/4 an 1/2") to plug various unused ports.

As to your original question, I run a 4ze1 with no emissions equipment other than the charcoal canister and it runs fine. Not better than it did before the delete, but exactly the same...
 

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Discussion Starter · #8 ·
ok. so i figured out how to do the smog removal. pretty easy and straigh forward.

now i cant figure out how to put all the rest back together. like the wiring harness for the fuel injectors and the air lines going to it all.... help?
 
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