hi all,

ive finally got my seriess 3 xj6 on the road and although the old 4.2 xk engine runs well and seems to do what i want i cant help but think about how nice a 4 speed auto would be. if i ever have gearbox issues or a blown headgasket ide be inclined to swap rather then repair

i have 2 thoughts,

the first is an aj6 from and xj40

the second is a 4.0l ford engine that is very common in out Australian falcons. its as common and as bulletproof as they come and has a very good electronic 4 speed auto and efi system attached to it. its no jaguar engine tho.

currently ide be more inclined to go the aj6 as its much more advanced and powerful but the ford is a really good and deserving engine. its cheap, reliable and not that bad on fuel.

ide love to hear from someone with an aj6 conversion. especially what they had to do and how fuel efficient it is.

i do love the xk but its a bit heavy on fuel and im no huge fan of the injection system, but the main thing is i believe it would be a much more pleasant car if it had overdrive.

otherwise any links / thoughts would be greatly appreciated.

regards jay

 

Jay,

A crowd here "Sovereign Auto Services" have done quite a few AJ6/trans swaps into S3, and from what I have seen and heard, very nice.

I think the 3.6 with ZF 4HP22 trans was used, but dont quote me, maybe 4ltr were used also??.

I believe they once did a mounting kit for that task, but is was quite a few years ago.

 

From what I've heard the fundamentals of the swap are very straightforward. That is, getting the engine and transmission mounted into the car.

LOTS of details after that but it's quite doable, as Grant says.

I'd want the donor car alongside so whatever must be/can be used in the swap is immediately at hand.

Cheers
DD

 

Jay,

I fully appreciate what you are saying. I drive my XJ6 daily, and the fuel economy is the only negative thing I can say about the car.

One more option that you didn't list is the John's Cars 4 speed auto (w/OD) kit out of a later model GM car. Don't know if that would be easy for you to source down under, but that would give a more relaxed cruising gear, and I believe a little quicker off the line gearing as well.

The XK engine is still thirsty so I am assuming something like an AJ6 would be more effiecent, but not sure.

Hopefully we'll see some more comments on this thread.

Eric

 

Just drove my AJ6 powered XJS down to Bristol Classic Car Show and back to London, which is about 90 miles each way.

On the way there at 85-90mph it indicated about 25mpg. On the way back at 70mph I was getting 29-30mpg... unitl I got bored.

Saw an xjs the same colour as mine but with twin headlights as I was approching the M25 on the way back!

 

Hi Aussie ser 3 i have done several of these conversions useing the 3.6 with 4 speed ZF and 5 speed getrag manual.One was my XJS which was a v12 now a 3.6 with 5 speed as my race car with the AJ Engngeering revised inlet manifold and bored out airflow meter and throttle body..The others were series 3 and a series 2 both done for customers . The 4 litre has the sport mode in gearbox which has its own ECU that makes it a bit more difficult. To start off the engine mounts can be sourced from the 3.6 XJS as they are the same front suspension and cross member as series 3. If you go ahead on an AJ 3.6 OR 4 LITRE keep in touch
Cheers Ray from down under

 

so overall it seems pretty easy and worthwhile.

can you use the 4.0 xjs mounts if your using a 4.0 engine? ide be more inclined to use a 4.0 because they are more readily available here in aus and i wouldnt mind more torque.

how does it sit in the series 3 engine bay. ide assume better then the xj40 because the series 3 was designed for a v12 but the xj40 was not. being slanted ide be interested in seeing how they look.

hows the gearbox mount need to be modified? can you keep a series 3 shifter?

ide imagine you can just strip the loom out of the xj40 and basically connect up the gauges, fuel pump and power feeds? is there any bypassing or hacks needed ie an immobiliser?

thanks for your opinions,
jay

 

Very much looking forward to seeing more on this. I agree, I'd love to see some pictures of the AJ6 engine in an XJ. Also more details on what is involved electrically.

Ray, by chance do you have or can you get some mpg figures for those cars you have converted?

Are the ZF 4 speed auto and Getrag 5 speed manual the only 2 trannys offered for these engines?

Thanks,

Eric

 

Hi the engine mounts are same as 2.9 single over head cam 3.6 and4.0.surpriseingly the part numbers are the same on all AJ blocks; Jaguar just altered the stroke except the 2.9 had the single overhead cam which is the same head i beleive as the right hand head on the V12.The gearboxes i mentioned are the only ones i have used mainly because of the starter motor is on the correct side; Series 1-2-and 3 are on opposite side. I have heard of Toyota supra or seleka gearboxes fitted but i think they were to the earlier XJ SERIES. The series 2 and 3 were averaging 26 to 27 mpg iff not 2 heavy footed. There is more room in the engine bay of the series 2 and 3 than the XJ40 untill about 1994 when they fitted the 6 litre v12 and widend the chassis.The series 3 shifter could be modified to fit but i prefered the J gate on ZF box.I had to modify the console and tunnel a bit cutting the tunnel from a wrecked XJ40 and fabricating to fit series 3. The wireing is easy all you need is the xj40 MAIN ECU and find a home under the left hand side of dash maybe behind the glovebox and the wireing harness on engine for the injection and ignition module -coil -crankspeed sensor.In the wireing loom near the ECU there are 3 relays you need. I will have to look up my own diary for the wireing colour code for ignition from your existing series 3 ignition and fuel pump also the revcounter -oilpressure switch and temp switch. The only hassle i had was running the speedo depend on wether yours is cable or electronic
Cheers Ray

 

The series 2 was a bit more work as they were not fuel injected unless V12.Ifitted series 3 fuel tanks as they have larger fuel feed +fuel return pipes also needed series 3 solenoids and change over valve. But the wireing was basicly the same as series 3. On both cars i used XJ40 radiator and header tank. by using xj40 radiator you have auto trans cooling on one side and power steer cooling on the other side. I can elaborate on other issues latter sa there will probibly be some iff you go ahead with it. Time to return to my man cave for a beer
cheers Ray

 

This is some great info. I just remembered that there are differences in US mpg and UK mpg. For example 20 mpg US = 24 mpg UK Which mpg version does Australia and New Zealand use?

Thanks again for the info.

Eric

 

Hi ronin im fairly certain Australia and N Z are the same as UK
Cheers Ray

 

ok, 26~27mpg UK = 22mpg US.

So here's my run down of Jaguar engine/automatic tranny combos as I understand:

4.2L XK engine (series 3 w/ fuel injection) and stock BW 3 speed non-od:
16mpg US/19mpg UK (this is what I average which includes some highway miles)

4.2L XK engine and GM T700 4 speed w/ od (John's Cars conversion kit):
Not sure, I haven't seen anyone post mpg #s, but my guess is 19mpg US/23mpg UK should be possible. Can anyone confirm some mpg #s with this setup?

3.6L AJ6 engine and ZF 4 speed w/ od:
22mpg US/26mpg UK

Does this sound right to everyone? Would the 4.0L engine get better, same or worse mpg? Is the AJ16 engine an option or too difficult to wire up? If possible, any ideas on effect to mpg?

Eric

 

Ray,

One more question, I just remembered that the AJ6 engine should weigh less than the XK engine. Were any changes made to the front suspension of the cars that were converted?

Thanks for all the insight.

Eric

 

Sounds plausible if a fair amont of highway driving is included, as this is where the OD 4th gear would have the most effect, I'd say.






The AJ16 might not be that hard to wire up if a non-electronic transmission was used...but I wonder how heavily the transmission electronics are integrated into engine management electronics. It might not be feasible. I'll do some mulling.

Cheers
DD

 

Hi Eric
Thats correct the AJ engine is slightly lighter but did not make a big difference in ride hieght' i think from memory i removed nylon spacers under front springs on one car and put spacers between bottom spring pan and lower arms.It depended on how the customer wanted it set up.I will try and dig out some photos today as it was back in 203 and 204 when i did the series 2 and 3. I am semi retired now and mainly work on my own projects sa i have plenty to do. I will be fitting a 4.0AJ to my series 2 coupe at some stage for now i amgetting set up to fit a 5 speed getrag to my 1976 XJS.
To Dougs reply the ZF 4-HP-22 Auto trans needs no wireing as the kick down is cable these were fitted to the 2.9 + 3.6 . The ZF 4-HP 24 which were fitted to the 4.0 were electronic with sport mode could be more of a problem i have not fitted one of these for that reason. my preference is 5 speed manuals but not easy to find here in NewZealand.Ihave collected 4 x 5 speeds over the last couple of years for my retirement projects. All Jaguars should be manuals and all daimlers be Autos.
Cheers Ray from down under.

 

Ray,

I like your thinking. Which model Getrag 5 speed bolts up to the AJ6 engine? Here in the US, I don't believe Jaguar shipped any manual tranny cars, but I wonder if the same tranny was used in a BMW or something.

Do you know which model of ZF was installed in the XJ40 cars, ZF 4-HP 22 or ZF 4-HP 24?

Looking forward to some pics, thanks again for the help!

Eric

 

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