Few weeks ago I bought nice looking (on photos) 2001 4.0 sovereign from a nice guy in Switzerland.
Ex owner told me that the engine starts, but is uneven on idle and stops after some seconds.
I was expecting to have 1 tooth misalignment on some bank, but when the car arrived on friday same night it turns out that secondary timing chain was snaped on left cylinder head.

Today I removed everything except damping pulley and timing cover, so I can pull the head off, but I was wondering is it possible to get something more in terms of performance, while rebuilding this head.

As I know AJ26 have intake camshaft with slightly wider duration than AJ27.. So now I'm thinking to buy intake camshafts from AJ26 and change triggers from my camshafts.
Also I have on the shelf exhaust manifolds from AJ33, which looks better with right couple of cylinders grouped, not like earlier all in one type. And as I understand, it is not possible to take off exhaust manifold, without pulling the head or dropping the whole engine, so maybe now is the right time for this.

How do you think guys.. Is it possible to get some ponies from these mods?

Cheers,
Christo

 

Just a heads up- you may want to remove the exhaust cam from the broken chain side and to a compression check before rebuilding- unless you want to rebuild anyway.

 

Thank you mate!
Anyway I'm quite sure I'll have 0 compression on cyl #3 on this bank



Maybe it is hard to be seen, but it is obvious that cam followers on this cylinder stays deeper than others.
I'm sure I have bent valves on those cylinder. Anyway I hope there is only 2 exhaust valves for change. (cross fingers, Cyl#4 valves survived).
Today I already ordered 2 exhaust valves, but for Range Rover 4.2 supercharged (2 times lower price, than the same thing from Jaguar).
However I'm not comfortable only fixing broken parts
It is not reasonable to do repair job without some "tuning"

 

You are in for some pain with the valve spring keepers! They are tiny.

 

Hello, if you can fit the AJ33 exhaust manifolds into your car- there is definitely some benefit - as yours is not a supercharged. You will gain about 20-30 Nm of low speed torque due to pulse tuning and good separation of exhaust pulses.


It is correct that the original AJ26 has longer duration cams than the AJ27 (240 inlet period vs 230) but an overhyped Austrian consultancy screwed up the inlet ports so badly on the AJ33 that that engine went back to 240 period cams to get the power back. IN addition the AJ33 has 'larger diameter' (not actually larger but the tappet top has a bigger diameter wipe' area) graded bucket tappets and the cams take advantage of this for greater accels. The AJ33 cams also has shorter ramps- which has a BIG impact on low speed torque and some on power too. So Aj26 are longer duration - but I don't know if you can get hold of AJ33 cams and tappets too? That could help.

 

Thank you very much for this valuable info! (as always)

Sure I'll pull also the right head, so I can put AJ33 exhaust manifold on it, and maybe some mild polish on ports (I'm not a fan of over ported heads on NA engine).

Do you have any idea about Land Rover 4.4 equivalent of AJ33 engine?
I can get those heads and if they use the same cams and buckets as AJ33, they will be perfect choice for me. (it is mentioned that valves and seats are toasted - maybe improper lpg tuning and this is not a problem for my case).

btw.. is there different ramps on exhaust cams of AJ33 also or it is only intake cams, that changed from AJ27?

Cheers,
Christo

 

BUMMER- I can definitely see you have bent valve(s). I would personally like to hear and see if polishing gives a better sound/snap to the throttle.

 

The Land Rover equivalent to the AJ33 - the 4.4 litre is known as the AJ41. It has similar Cam Profile developments.
the heads themselves should be the same as the AJ33- they are nasty ports for a 300 Bhp engine- but they ARE a good basis for porting- as they have alot of metal to be fettled

 

What about exhaust cams in aj33? Are they different design too, or they are equal with aj27?

Wait a minute.. You mean that this Austrian consultancy guys make changes in the head ports for some flaps, that was ditched after that?
I was thinking these changes was made on intake manifold.. I didn't realize the head casting was screwed.

Anyway, I think I will use my own (AJ27) heads, and just "implant" in them AJ33/AJ41 cams&buckets

These evening I manage to take damper pulley bolt off, and after that I realize that it is not possible to remove the pulley without the right tool. So tomorrow I must try to make the tool for this.

Cheers,
Christo

 

The Exhaust cams on the AJ33 also have lower ramps and so benefit.
Yes! How do you know about the flaps?
The flaps were supposed to be in the lower manifold- which I still there but now it serves no purpose.


The ports were compromised based on the reccomendations of those clowns and they aren't optimised the way they should be. The Aston Martin Ports are a lot better and for the smaller engine size the AJ27 ports are good too

 

Thanks again!


I read somewhere about these intensions to use some flaps in the intake.. maybe in your posts somewhere, but I'm not sure.
It is strange thing, because at this time almost everyone already trashed the idea of blocking some part of intake port, to gain velocity.
I have also Celica ST205 with 3S-GTE engine, and it is rally funny to see 2nd and 3rd gen 3S-GTE heads side by side.
Even VW throw out this design on FSI engines after short usage.

However I don't know why Jaguar don't use variable length intakes back at these years, while it shows good results in flattening torque curve.


Anyway I already ordered another set of 10 headbolts, so right head will be also down for "maintenance" with another cams, and exhaust mani.


Yesterday I dropped an e-mail to one nice guy (best local remaper) asking him to check possibility to switch off downstream o2 sensors, so I can make decat downpipes for X350 manifolds. Unfortunately DENSO injection system (even don't know how they call it) is not so well known like Bosch motronic here.

 

How much is peak intake port flow for stock AJ33 head? Data shows that it's at 0.3L/D: 0.55 for X308 4.0 XJR / (Alpha K ) : 0.16

What are exact combustion chamber volumes for 4.0 and 4.2 heads?
Can not find this data from any engine manuals.

 

I was involved in some prototype work using a variable length intake manifold for AJ33. It gave a lot of torque. I wanted it included in the assumptions pack for AJ33- but it was dropped. I was a young engineer at the time without any clout and the Ford worshippers kowtowed to them. That's why we wasted money on Flap rubbish. In my view the AJ33 should have been a lot more different to the outgoing AJ27.


Where I work now, things are different and i'm older and I push things to happen.


Yeah, Denso is a bit unknown here in the USA too

 

Count Iblis: Do you remember combustion chamber volumes for 4.0 and 4.2 heads?

 

AJ27 42.5cc


AJ33 little over 44

I checked my files and I don't remember sorry. I looked up my values on my valve clearance spread sheet- and I found about 42.5ccs for the AJ27 (10.75:1) and a little over 44ccs for the Aj33 4.2 (11:1 CR). There are a lot of academic assumptions from my data such as a nominal head gasket thickness and nominal tolerances etc. My data is from old CAD and calcs and has some tolerance values but its never as accurate as actual measurements- so you're better off measuring anyway.

 

You got those X308 numbers from my website didn't you?


The AJ33 head DOES flow better- but it didn't initially and we only achieved it last minute through bigger sizing with nasty transitions and removing a lot of the squish that the Austrians recommended which was flow shrouding. It flows 0.6 at 0.3 L/D which is about 0.17 Alpha K. It definitely respresents a good starting point to start modifying a performance Jag V8 but as an out of the box OEM design that had to meet emissions etc for the size of port it should have been better- like the AJ27 was.

 

I'm really glad to see this tread start ro collect such interesting data.

Yesterday evening I manage to pull the head off, and leave it @ head workshop of a friend to check if only exhaust on 3rd cylinder were damaged. The good news is that really only these two valves are bend. The bad news is that land rover valves that I ordered are on backorder, so it will take 2 weeks instead of one to be delivered.

Tomorrow evening I'll visit this friend with AJ33 exhaust manifold in hand, so I can check how they fit and to check how good is port design and casting imperfections of the head. From previous experiance of AJ16 head I must admit casting is pretty good, not like old fiat castings, that looks like I was doing it on part time job in a hole in the ground

Forget to mention that I measured intake camshaft lift to be 9mm.. It seems pretty low number for NA engine.

I didn't measured until now intake port cross section, but anyway I think 9mm is too mild.
Btw.. Is there a difference in cam profile for different capacity NA engines in the same era? 3.2&4.0 for AJ27 and 3.5&4.2 for AJ33. I noticed that cams have different part numbers, but I dont't know where is the difference.

 

This is your website? 1998-2003 Jaguar X308 XJ8(R)- An under rated scorching luxury Saloon | Auto-Scape

 

The Landrover valves are about 105mm, instead of the 101.5 from Jaguar.

 

Yes it is!