Hi all. I've been following this forum off and on for the last 4 years that I've been working at an independent Jag shop. The other day I became the proud owner of an 01 coupe w/ 58k whose owner did not upgrade the tensioners. Two exhaust valves into the B3 or #7 piston, combustion chamber damaged. Not a big deal as the cylinder wall was not damaged, just needs a piston and rings.
So here's the question- are the AJ26 and AJ27 B (left) side heads the same except for the cams? If not, what's different? We have some used heads at the shop that look the same, but I haven't yet done a thorough exam.

 

I've not tried using AJ26 heads swapped for AJ27s or reverse, so I cannot speak to every bolt, hole or dimension, but a couple of obvious differences that you'll need to inspect closely.

1. The AJ27 upgraded from one to two cam position sensors. The change was made on the A bank. If you're comparing the B bank, the AJ26, with one cps, came through the B bank, just make sure the AJ27 sensor fits with the same location. The sensor from your engine/car must be used along with your cams if you're going backwards to an AJ26 head, but, I personally would not swap cams that have been worn in on one set of cam journals in another set of worn journals
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2. The solenoid used on the VVT enters from a different point on the AJ26. It came in on the front of the cylinder head. The AJ27 moved it to the cam cover. A blanking plug was installed for AJ27s, but I don't know if you can field install one in an AJ26. The VVT units and carriers are upgraded in the AJ27, so close inspection to see if all the correct clearances and machining exist for the AJ27 VVT assembly will be important.

3. Your MY AJ27 should be using the single row primary chain, not the Morse chain, so all that should be compatible.

4. Intake manifolds are different between an AJ26/AJ27, however, I cannot think of any impact on the cylinder heads themselves.

Every other aspect of the heads, valve sizes, valve angle, cam, shim clearances are the same, but if it were mine, I'd keep searching until I found the correct AJ27 replacement head.

 

thanks, Steve.

I know about VVT, actuator, cam differences, sensor. Point taken on cams into another head. As it turns out, I have a complete w/ cams AJ27 head here, so I'm in good shape.

John

 

car is all together and running smooth as silk. 1 piston, 1 head, gaskets, hoses, etc. driving it locally to work out the bugs.