Need infos on head difference

BigDan

TJ Enthusiast
Supporting Member
Joined
Aug 21, 2021
Messages
120
Location
St-Jean Baptiste , Quebec.
2005 LJ , auto ,

I want to modify the engine , get the compression ratio to around 9.0 to 1 ,
Will port the int/exh ports , shave around .040 to obtain my desired CR ,
Plan to work on the exhaust system too
Read that the original 2005 head is very restrictive


I did it on my 98 4.0L that is in my 86 CJ , got way better power/torque and gained economy ,,,,,,dynoed at 237 hp, very satisfied !

So I need to know :
Will a 0630 or 0720 head casting ( 91-99) fit on my engine block without major mods ?
Are the original exhaust manifolds fit direct ?
I plan to install doug thorley headers ( reason that I need to know if fits on both heads )

Thanks
Dan,