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4.0l ho head to a non ho 4.0 block

JASPERW_13

NAXJA Forum User
Location
virginia
is it possible to put a 91-later HO head on a 90 non HO block using the 90' intake and exhaust? If so would it be worth doing or would i need to swap manifolds to get any type of power increase?
 
Been there, done that. Its a great swap (4.0 HO ported, 3 weber 45DCOE, roller rockers, bigger valves offset for improved flow) on a 258 motor. There are several good sites covering the swap in great detail. Search on google but start with the link below.

http://monsterslayer.com/jeep/40Head/40Head.htm

John
 
More to the point of your post:

The head fits the non HO block just fine and you dont have to plug the water passages. Change to headers, port match and use your old manifold FI system. Did the swap on non HO 4.0 block that was put into a Rambler Classic. We had to make big changes to the fuel system for the FI which you wont.

John
 
thanks for clearing things up. I have been reading about some guys putting a ho motor in a non ho xj and having to cut and splice and chang out cables and i really wasn't looking forward to it.
 
I would consider drilling/tapping more of a pain than a few wires and lines if you have the parts/funds available. The hard parts I found were adapting the TPS & fuel lines (which wasn't that hard IMO). I believe you'd just need the new exhaust, tranny kickdown cable, accel cable to use the new intake, as all the other sensors from the old motor should fit right in.
 
Are you doing a head swap or a motor replacement?

The head swap is simple.
The motor swap may not be.
 
nosigma said:
Are you doing a head swap or a motor replacement?
The head swap is simple.
The motor swap may not be.

I have a 93 HO in my 89 renix system right now.
This was my first motor swap ever. From the head down everything is basicly the same; the intake is where everything got kinda complicated.

My above comments concern putting an OBD1 HO 4.0L engine into a Renix 4.0L system.
 
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