Is the 0331 head a high output, or is it a regular head? Also how can i identify the block to know what year its from?

 

00-01 have these heads. I don't believe any older XJ's did.

 

Get the number off the driver's side of the block.

 

i found out the block is from a renix era xj. is the head still a high output? because i a going to build a stroker and wanted the HO head and intake manifold

 

0331 heads are prone to cracking between the #3 and #4 cylinder.

 

all I6 heads are prone to cracking. just some more than others lol

 

Not true at all.

 

Get the number off the head. Driver's side about 1/2 way down.

 

Agree with cruiser54 that not all I6 heads are prone to cracking.

Actually the heads from 87-99 are quite hardy.

It's the 00-01 that you need to keep your eye on because of the casting defect between cylinders 3-4.

 

the guy down at the machine shop has seen cracked heads from all years and so did the engine i just bought, 88-90 block with a 2004 head cause the old head cracked

 

from the reasearch i did, the head i have appears to be the revised 0331 that has "TUPY" stamped on in

 

Machinist is mistaken.

 

clearwater cylinder heads makes the aftermarket 0331 head i just bought. it is beefed up in the 3-4 clack prone areas.

 

the head i have is a "revised" 0331. anyways, found a crank and hope to buy it tomorrow

 

Is crack between valve seats?