Hello forum,

restoring a XJS V12 5.3 with the HE engine. Lucky us we got this almost rust free example, it had a blown engine when we got it.
So now getting the engine back to life, we are having sever problems finding pistons for the HE engine. We also have a XJ12 with more or less the same V12 engine, so thats even more shocking since we are not new to the jaguar engine world at all ...

Our model is the european version with the higher compression, well I guess we would be OK to get 12 new pistons with only the 9.5:1 US compression if this solves the problem.

Anyone can help where to get jagaur pistons here in the US?

thanks

If it comes right down to it I'm sure a set of pistons can be made to order....for a price. It isn't particularly unusual to do so.

It might be easier and cheaper to find a different engine rather than overhaul the existing one.

On the HE engine the high versus low compression ratios were 11.5 and 12.5

Cheers
DD

I am building a V12 ATM and it is cheaper to bore the block for 95mm liners and use Chev 305 pistons than to have custom pistons made. I think my total cost was about $2000USD. You will also have a 6.0L from 5.3L

Thanks for all the infos so far ... but does this actually mean that there are no more stock pistons for the HE5.3 available at all (?)

Three minutes of Googling revealed nothing. But, that obviously doesn't prove that none exist.

Pre-HE pistons seem to be plentiful. One can presume there's a higher demand and thus a supply.

Cheers
DD

Home of Classic Jaguar and Team CJ

Could ask these guys if they have anything to sell, or what options are out there. Based out of Texas.

My british car mechanic might have spares to.

Part number for the piston and liner is JLM1960, it is listed at a number of USA dealers, so perhaps there is still some stock in the warehouse? David Manners in the UK list it as available, but inquire before ordering. Jaguar Partno_JLM1960#_PISTON V12 ENGINE_David Manners Group

New OEM V12 HE pistons are no longer available. Pre HE are, and liners for the 5.3 HE which are the same as for the 5.3 pre HE are.
Jaguar Parts by Model E Type S3 5.3L V12 - 12 cyl Engine Components

IIRC Mahle still makes the HE pistons... But that is probably not OEM.

How do the pistons distinguish if they have the high or low compression?
Same part number?

Thanks

All Marelli HE engines had the same 11:1 (?11.5:1, I forget) CR. Earlier Lucas HE engines for the USA had the 11:1, UK and many other markets had the 12.5:1. I have tried both CR engines in otherwise identival Lucas ignition UK spec cars and there is no power difference that I could detect. So as long as the pistons are all the same, I do not think it matters.

since it turns out to be so difficult to get pistons, I only need two actually with the 12.5 compression.

Since the piston would look different I think, I am confused if they have the same part number (?)

The High CR pistons have a different part number JLM1959 and were Europe only, the rest of the world got the low CR.

Greg is correct all Marelli engines are 11.5:1.

I think your only 2 avenues are to find used or buy a complete HE engine or have a set of custom pistons made.

I will say it again 96mm liners and Chev 305 pistons, a bit of machining is needed and is completely invisible. 6.0L way more torque and better fuel efficiency. And can be done with stock ECU.

JLM1959 is high compression (12.5:1)
JLM1960 is standard compression (11.5:1)
Both numbers are for the piston and liner assembly together. Jaguar didn't sell pistons for the HE engine separately. As mentioned upthread, Mahle might make pistons for the HE engine, without the liner.

Lucas ignition was 12.5:1 for Europe, 11.5:1 ROW, Marelli was 11.5:1 across the board, 6.0 litre was 11:1 for everything I believe.

I'm digging this idea. Any more info on it?

Norman Lutz used to sell big bore kits, I know he has built at least half a dozen 6.0L's from a 5.3L.. Next time I talk to him I'll ask if he still has the kit available.

Basically
My Jaguar rods were modified for a Chev wrist pin, plus I lightened them further.
Bore the block for the liners.
New 95mm liners although you could go 96mm and oversize 305 pistons
Pistons are KB145 with the 6.0L crank they needed 0.040" off the crown then the dish machining to lower CR to 11:1

Over 2kg was removed from rotating/reciprocating weight

a possible answer may be that there is no call/market for those type pistons ,so none are manufactured,, mainly that the HE engine does not lend itself well to performance modifications!
Pre HE is more modification friendly so more people buy parts! less costly.

Jags cars have a tradition of losing resale value,(sad shame), so to spend quite a bit of money on engine is rarely done! you can buy complete cars for less than a PROPER engine rebuild!

and like has been said there are many of the engines just laying around , and end going to the the smelter/crusher etc.
you may be better off to use some used pistons , i personally have sent 3 Jag V12 engines to to the great Chinese smelters!

BUT have fun with your endevuors.
ron

Hi warren,
you are talking about an HE engine, correct? I would be interested in options for a pre-he.