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4.0 Head Question


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something tells me no, and i think its cuz i someone told me that they changed the engine block slightly...but i don't think thats correct...

 

everthing from 91 on was an HO head? so even though it doesnt have the badging its not like ur 89. i think u will eng up running into electrical issues

 

BUT it would be a good power gain if you could get it to work with the renix wiring

 

somebody correct me if i am wrong, I'm going off of little tid bits that i've read

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It can be done, but it will take some work. Here is a little info that I found in one write up about it...

 

The other issue that required some time was mixing different generations of EFI. The truck was 1989, non-HO. The new engine and intake was 1993. Rewiring the truck to use the HO computer was considered, but this task was considered too unwieldy. Instead, the older Renix (non-HO) EFI was retained and fitted to the HO block and intake. To get the engine running, the following tasks had to be done:

 

-Fit the older TPS onto the newer throttle body: the new TPS is not at all compatible with the older EFI.

 

-Re-wire the temperature sensor: on the non-HO block, this sensor is located on the driver's side of the block; the HO block locates this near the thermostat, which will produce a more accurate reading.

 

-Mate the non-HO fuel lines to the HO intake: the HO intake has both the fuel feed and return lines at the front of the fuel rail; the non-HO intake places the fuel feed at the back of the fuel rail, and the return line at the front.

 

-We used all of the older engine brackets to hold the air conditioning compressor, alternator, etc.

 

-We also used the non-HO distributor and flywheel to use the non-HO sensors. This is absolutely necessary, since the non-HO and HO flywheels are keyed differently.

 

-An HO throttle cable had to be used, and a slight modification to the gas pedal was needed.

 

-The HO exhaust header is needed with the HO cylinder head; luckily the non-HO oxygen sensor fits the HO header.

 

-The HO injectors that came with my new block had been sitting too long, and every one had become completely seized, or gummed up from old gas. In the interim, I used Ford Mustang 5.0L injectors, as they are cheap and compatible replacements for Jeep injectors. These injectors will have to be replaced with larger ones. Flow testing various injectors confirmed specifications that were finally located:

 

Stock Jeep non-HO injectors 201 cc/min; 19.7 lbs/hr

Stock Mustang 5.0L injectors 194 cc/min; 19 lbs/hr

Jeep/Chrysler #33007127 injectors 225 cc/min; 22 lbs/hr

Jeep/Chrysler #53030778 injectors 235 cc/min; 23 lbs/hr

 

The flow testing also indicated that Jeep injectors have a very narrow spray pattern whereas the Ford injectors spray at about a 60-degree spray pattern making them a better choice in terms of air/fuel mixture. Further research indicates that Ford injectors that should be compatible with the Jeep injector rail can be found in 22, 24, 30, and 36 lbs/hr flow rates. For this application, injectors in the range of 23-24 lbs/hr seem ideal.

 

The complete article is here... http://www.bc4x4.com/tech/bryce/stroker/install.cfm

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F@#$ all that mess for just a few HP I'll have to save up and do something else. I was able to get the upper end of the 98 motor minus the intake and exhaust for a good deal and was thinking if it would be easy enough to swap heads and cam I would but now its not sounding like I'm going to do that, to much BS. thanks for the info

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I was reading over taz reply thats for swapping the whole motor I want to swap just the head and cam and still use my intake and exhaust if it will work. The guy I have been talking to doesnt have the complete motor. Well he does but it threw a rod.

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Thats ok. So its not as big of a project then. Just rewire the temp sensor thats not so bad. So the only thing left to know if my intake and exhaust with fit to that head and the cam will fit in my motor. I don't care about the O2 sensor mines not hooked up now so thats not a big deal. Its the bolt holes I'm worried about.

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I know that the exhaust manifolds are not interchangeable between the HO & non-HO, but I am not sure about the intake. Try some google searching on this too... ;)

 

I know nothing of the cam situation as I was never an internal engine tech in my years of being a tech.

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F@#$ all that mess for just a few HP I'll have to save up and do something else. I was able to get the upper end of the 98 motor minus the intake and exhaust for a good deal and was thinking if it would be easy enough to swap heads and cam I would but now its not sounding like I'm going to do that, to much BS. thanks for the info

Two things I haven't seen mentioned yet:

 

(1) The 97 and newer heads aren't drilled for the temperature sender that controls the dash gauge. On the OBD-2 systems the gauges receive input from the central data bus, so there's only one temp sender. The Renix has one in the head for the gauge, and one on the block for the ECU.

 

(2) The height of the ports was raised and the shape changed in 91 when the HO engine came out. It is theoretically possible to fit the old Renix manifolds onto the new heads (it has been done), but it's a far cry from "bolt-on," and whatever gains you might otherwise get from the HO head you probably lose because the mismatch between the ports and the manifolds messes up the air flow. It's better to change the manifolds if you change to an HO head -- but then you get into throttle body and linkage issues.

 

BTW -- the cam in the 4.0L is not "upper end" stuff -- it's in the block and would not be touched by a head replacement unless you choose to also replace the cam while the engine is halfway torn down.

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