1975 Jaguar XJ Coupe 6.0 V12

[craigjm]

When it is 100% complete with nothing at all left to do there will be an unveiling at the next PH Sunday Service. Going to try and arrange this so they can do an article on it.

[bob-lad]

[mark387mw]

This one looks nice and shiny

https://www.trademe.co.nz/1278822147 Chassis:252337BW

[fatbutt]

Anyone see this?

http://jalopnik.com/this-corvette-powered-1976-jag...

[Minemapper]

fatbutt said:

Anyone see this?

http://jalopnik.com/this-corvette-powered-1976-jag...

That is very tasty indeed. Not much I would change at all.

[craigjm]

The turquoise car is begging to be lowered

I have been battling with what to do engine wise with mine and have considered a 430bhp LS3 although I like the calm waft of the v12. I will get the car how I want it and then think if I go for the heart transplant although it would almost definitely destroy the cars value in the UK but I guess to some I am doing that anyway

[bob-lad]

I bet some sporty 2½" stainless pipes on the V12 will make a very special sound indeed.

[fatbutt]

craigjm said:

The turquoise car is begging to be lowered

I have been battling with what to do engine wise with mine and have considered a 430bhp LS3 although I like the calm waft of the v12. I will get the car how I want it and then think if I go for the heart transplant although it would almost definitely destroy the cars value in the UK but I guess to some I am doing that anyway

I thought that when I put an LS3 in my rolls but at the time the rolls was only worth about £10K. The LS3 has given me a far more reliable power plant that is emmissions compliant (of that matters) and also 20+ mpg (again, if that matters). The engine note is gruff and not as smooth but you can tune that with the exhaust. A big difference you'll find though is in the weight: the LS3 is about as heavy as cotton wool compared to the cast iron lump I had in there. The same should be the case for you. It messes up the front suspension and also handling CoG will move. I've also found that the jacking points below the car are now next to useless as you end up lifting 1/2 the car off the ground instead of one wheel or the other. I loved the experience of doing all the work and drive my car every day, so it worked out well.

[craigjm]

bob-lad said:

I bet some sporty 2½" stainless pipes on the V12 will make a very special sound indeed.

engine wise which is a long way off as its last thing I will consider I am thinking options not concerned about acceleration speed here -

Option 1 - Cost Zero
Keep the 6.0 v12
Live with the 15MPG

Option 2 - Cost about 3500
Keep the 6.0 v12
Add a gear vendors overdrive kit
Should return about 21MPG

Option 3 - Cost 2100
Keep the 6.0 v12
Add LPG
Should return equivalent of 28MPG

Option 4 - Cost 5600
Keep the 6.0 v12
Add LPG
Add Gear Vendors overdrive kit
Should return equivalent of 40MPG

Option 5 - cost 12000
Junk the 6.0 v12 and replace with LS3 6.2 430BHP
Should return equivalent of 25MPG

[EJH]

craigjm said:

engine wise which is a long way off as its last thing I will consider I am thinking options not concerned about acceleration speed here -

Option 1 - Cost Zero
Keep the 6.0 v12
Live with the 15MPG

Option 2 - Cost about 3500
Keep the 6.0 v12
Add a gear vendors overdrive kit
Should return about 21MPG

Option 3 - Cost 2100
Keep the 6.0 v12
Add LPG
Should return equivalent of 28MPG

Option 4 - Cost 5600
Keep the 6.0 v12
Add LPG
Add Gear Vendors overdrive kit
Should return equivalent of 40MPG

Option 5 - cost 12000
Junk the 6.0 v12 and replace with LS3 6.2 430BHP
Should return equivalent of 25MPG

To my mind, it's option 1, 2 or 5.

I didn't think I would like the execution of an LS3...but having seen the videos of those done, I can see the advantages.

As I've said before, it's neither my car nor my budget so just my opinion!

[bob-lad]

craigjm said:

bob-lad said:

I bet some sporty 2½" stainless pipes on the V12 will make a very special sound indeed.

engine wise which is a long way off as its last thing I will consider I am thinking options not concerned about acceleration speed here -

Option 1 - Cost Zero
Keep the 6.0 v12
Live with the 15MPG

Option 2 - Cost about 3500
Keep the 6.0 v12
Add a gear vendors overdrive kit
Should return about 21MPG

Option 3 - Cost 2100
Keep the 6.0 v12
Add LPG
Should return equivalent of 28MPG

Option 4 - Cost 5600
Keep the 6.0 v12
Add LPG
Add Gear Vendors overdrive kit
Should return equivalent of 40MPG

Option 5 - cost 12000
Junk the 6.0 v12 and replace with LS3 6.2 430BHP
Should return equivalent of 25MPG

Absolutely, I was purely thinking of aural performance enhancement

I'd go essentially with option 1, then option 2 some time later if necessary.

[anonymous-user]

craigjm said:

engine wise which is a long way off as its last thing I will consider I am thinking options not concerned about acceleration speed here -

Option 1 - Cost Zero
Keep the 6.0 v12
Live with the 15MPG

Option 2 - Cost about 3500
Keep the 6.0 v12
Add a gear vendors overdrive kit
Should return about 21MPG

Option 3 - Cost 2100
Keep the 6.0 v12
Add LPG
Should return equivalent of 28MPG

Option 4 - Cost 5600
Keep the 6.0 v12
Add LPG
Add Gear Vendors overdrive kit
Should return equivalent of 40MPG

Option 5 - cost 12000
Junk the 6.0 v12 and replace with LS3 6.2 430BHP
Should return equivalent of 25MPG

I would see a move to a V8 as a downgrade personally. Given the choice between any two Jaguars with a V12 in good health and a modern V8 I wouldn't look twice at the bdized car, 100bhp power difference or not. You could possibly get very good money from a genuine JaguarSport 6.0 engine though, if you can find the right buyer.

Have you considered fitting a manual gearbox? There is a chap with an XJR-S that has been converted and I'm told it has utterly transformed the car. Or you could consider a TH700 transmission swap if all you want is an overdrive gear for cruising. I know KWE offer these and I'm sure I've seen a few V12 Jaguars that have had one fitted.

[Alfa Pete]

Harry Metcalfe seems to like his manual conversion.

https://youtu.be/7TMgIkx40tI

[craigjm]

I don't want a manual. One doesn't build a car like this then stir ones own porridge
The problem with the TH700 is that they are really hard to get hold of with the right bell housing for the Jaguar as it was not the same as other models

[Shakermaker]

craigjm said:

engine wise which is a long way off as its last thing I will consider I am thinking options not concerned about acceleration speed here -

Option 1 - Cost Zero
Keep the 6.0 v12
Live with the 15MPG

Option 2 - Cost about 3500
Keep the 6.0 v12
Add a gear vendors overdrive kit
Should return about 21MPG

Option 3 - Cost 2100
Keep the 6.0 v12
Add LPG
Should return equivalent of 28MPG

Option 4 - Cost 5600
Keep the 6.0 v12
Add LPG
Add Gear Vendors overdrive kit
Should return equivalent of 40MPG

Option 5 - cost 12000
Junk the 6.0 v12 and replace with LS3 6.2 430BHP
Should return equivalent of 25MPG

Option 1 or 2 from me.

[TheLordJohn]

Personally number 1, then if I couldn't do number 1 for whatever reason, number 2.
Never number 3, 4 and number 5 would be a bit of a fk up.

[craigjm]

Number 2 / some kind of improved gearbox is a bit of a no-brainer if you are going to keep the car for a long time which I pretty much am.

Number 5 would change the character dramatically but would make it lighter and faster I am just not a fan of getting rid of the original engine as surely part of the appeal is the v12

[bob-lad]

Is it too late to talk to the paint shop?

https://www.youtube.com/watch?v=v1WLblU0eNY

[Coatesy351]

craigjm said:

I don't want a manual. One doesn't build a car like this then stir ones own porridge
The problem with the TH700 is that they are really hard to get hold of with the right bell housing for the Jaguar as it was not the same as other models

Adaptor plate?

http://dellowconversions.com.au/product/gm-v8-th-7...

[fatbutt]

If you're looking at option 5, take a look at the e-rod package from Chevy. Its what I bought (6.2, 430HP) and it comes pretty much plug and play. All the other bits like belt drive/ pulleys, etc. can come from chevy too. I bought the engine and gearbox (TR6060) as one package but it also comes in automatic configuration.