Post by XJ Zone on Feb 8, 2016 12:27:40 GMT -4
So I’m doing my homework (google first 
) but was hoping for some feedback here.
I’ve got a ’00 XJ with a 4.0L with 320k km’s…so she’s had a good life, but I’m losing compression on cylinder 5. It seems to be the piston rings cause the others had about 120psi, it only had about 75psi, but after doing a wet compression test it jumped up to about 100psi. So in order to limit my down time and keep it on a budget, I’m looking into a new motor.
The 00-01 XJ seems to be the mix breed, using the 96-99 HO block used in XJ’s, TJ’s, & ZJ’s, along with the 0331 head used in ‘00+ TJ’s & WJ’s. I’ve read bad things about the 0331 heads used on the 00-01 XJ’s so I’d rather not replace it with another one. The 0331 head issues were supposedly fixed on ’02+ models, but the ’00+ TJ & WJ blocks are different.
My plan is to replace it with a complete motor from a 96-99 XJ, ZJ, or TJ with the 0630 head. I’ve got a lead on a 97 ZJ 4.0L but I’m not sure what exhaust manifold it has yet.
From what I’ve read there are 3 main differences between mine and the 96-99.
The older one uses a distributor and the newer uses a camshaft position synchronizer in its place, which can be swapped.
The newer one uses a coil rail which bolts to the 0331 head, but the 0630 head doesn’t have the bolt holes for it, but you can make brackets to attach it to the valve cover bolts, like this
The exhaust posts are smaller on the 0331 so my exhaust manifold won’t work on the 0630 head. Here’s roughly the difference
You can make an adaptor plate and sandwich it between the head and manifold using a gasket on both sides. This seems like a PITA and would restrict the exhaust flow.
The other solution is to use the manifold off a 0630 head, or buy an aftermarket header (which isn’t in my budget). Mine is an early ’00 model so it doesn’t have the pre cats and only has 2 O2 sensors. My manifolds look like this
After the manifolds, there’s 2 pipes that Y into one and is a single pipe right back to the cat. The upstream O2 is just after the Y
From what I can tell there were a few different manifolds used on the 0630 heads, but most look like this
I’d have to cut my pipe between the Y and O2 and add a shorter single flange pipe to match the 0630 manifold.
This can be done but I’m wondering if any of the 0630 manifolds are like my 0331 so I don’t have to modify the pipe?
If not, what 0630 manifold is the best to use, year/model?
I think some were prone to cracking.
I’d be reusing my 0331 intake manifold which is supposed to be better based on its freer flowing design and larger volume.
Has anyone else done this, am I overlooking anything?
Thanks for reading
