Jasper 4.0

Wes

Wes

Well-Known Member
Joined
Oct 14, 2007
Location
Ridgeway, SC
I’ve found a 2001 XJ with a Jasper 4.0 that I’m interested in. I have no other info. Haven’t contacted the seller yet. I’ve been told by many to stay away from the 2000-2001 XJ’s due to the head problems. Just curious if a replacement Jasper would have this issue. Tried to google the specs for jasper to see if it had the 0331 heads but no dice. Not sure if it’s a crate or remanufactured. Any ideas?
 
Cant ya just swap older 4.0 heads on it? My fav xj is 01 sport and I've seen maybe 3 out 30 with head issues all three had overheating which lead to warped head or cracks! I do believe Jasper's 4.0 has 0331 and I've heard of most common bad spot is between 3-4 cylinders!! not positive but I believe 2000 xj and zj were worst for head probs and cooling issues I'd say fawk it throw a 96 set of heads on it and roll on...?
 
Any casting with 0331 is going to crack when it’s gets hot. It’s pretty common for any XJ to get hot at some point so it’s almost a sure thing.
I put a 97 engine in my 2000 when it blew. Because I had a stupid CA emmsions jeep with dual cats right in the manifold I had to run an adaptor plate I found from a guy online. @Possumb84 has that adaptor now for sale in fact.

But yes you can swap heads on those engines with that manifold setup with that adaptor. It creates a very very small exhaust restriction right on the port but myself and many others have done the swap succefully with no issues.
 
C.Berry said:
Cant ya just swap older 4.0 heads on it? My fav xj is 01 sport and I've seen maybe 3 out 30 with head issues all three had overheating which lead to warped head or cracks! I do believe Jasper's 4.0 has 0331 and I've heard of most common bad spot is between 3-4 cylinders!! not positive but I believe 2000 xj and zj were worst for head probs and cooling issues I'd say fawk it throw a 96 set of heads on it and roll on...?
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True. I could always swap heads, but I’d rather be lazy and put the effort towards a bunch of light bars and stickers.
 
96-99 heads are 0631 or something like that!? They have dowel pins in same location if I recall but Intake ports are diff and ya gotta fab coil bracket I've not done this personally but it will work! You may be able to find a low mileage 03 head same casting I'm 70% sure they are less prone to the fuckery that 00-01 0331!!
 
C.Berry said:
96-99 heads are 0631 or something like that!? They have dowel pins in same location if I recall but Intake ports are diff and ya gotta fab coil bracket I've not done this personally! You may be able to find a low mileage 03 head same casting I'm 70% sure they are less prone to the fuckery that 00-01 0331!!
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You are correct, I forgot about the coil rail. I actually did not even make brackets for mine. Simply sticking it in place on the plugs, along with the wire harness and hoses on top kept that thing so secure it wasn’t going anywhere.
 
Wes said:
True. I could always swap heads, but I’d rather be lazy and put the effort towards a bunch of light bars and stickers.
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This is a valid and understandable point! @REDLYNER has hair gel and hookup on stunner shades FYI!
 
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