Hey guys. In rebuilding (building?) my first 6.0, I came across something I've not seen in any info anywhere. It started when I lost one of my spring retainers during disassembly of my heads. I found that there were two different part numbers, so I had the vendor send me one of each. In looking at them, it was very hard to tell any difference. However, be it visual inspection, or luck, I installed the correct one. Now fast forward to installation of Isky MX 5 cams, springs, and new valve lash caps. They came .170 thick. My clearances dictated on the A head anywhere from .153-.168 needed thickness. So far so good. Not my first rodeo in setting valve lash on a Jag V12. I decide to grind down my thinnest one first, in a effort to make the job seems easier as I went. I get it down to .153 on the dot, walk over to the engine, and DAMN! it won't fit in the spring retainer. I give up for the night. I call Isky today, and spoke with Nolin. Very nice, yet assured me that as far as he knew, nobody offers a 6.0 valve lash pad for the Jag!. The 5.3 has a valve lash pad that is .170 in diameter, whereas the 6.0 has a .610-.615 diameter! So....... it was to my good friend Bill who does all my weird machine work for me. (retired, and finds humor in my lunacy). He is going to attempt to put them in a lathe, and turn (grind) them down from .170 to .160 for me. What a pita....
With all that said, if any of you are thinking of installing aftermarket or reground cams in a 6.0, you may want to look at using 5.3 heads, or changing all the valves in the 6.0 heads to 5.3 valves and spring retainers.
Another alterative would be to buy a stick of hardened steel (maybe two feet) .160 in diameter, and using a cutoff wheel, cut your own.
If you are just adjusting your 6.0 valves, you will be fine reusing your lash pads, and grinding them, but be sure you don't lose one. Stock lash pads may be available, but felt some of you just "might" appreciate this tidbit of 6.0 information.

 

SS6
Is a lash pad what we call over here a tappet shim? Or is it something else, as 0.16 inch seems a bit too narrow to be the diameter of a tappet shim.
Thanks, Greg

 

Those diameters are dyslexic. .170" should be .710" and your stick of hardened steel should Be .610" or am l missing something right in front of me.
Jaguar show most thicknesses as being available.

 

Baxtor is completely correct. I think I am working far too many hours in my business to be involved in my hobbies. The lash pads, tappet shims, are .710 in diameter on the 5.3, and .610 on the 6.0. I just thought grinding the thickness was time consuming. Try grinding the diameter on one of these little suckers (X24). Not sure what the outcome will be just yet.

 

SC6
Grinding the shims thinner (rather than smaller in diameter) is, I believe, not a good idea, as you will remove the case hardening from the wear surface, and they will fail very quickly.
Thanks for the clarification, great project.
Greg

 

all you guys are correct! when doing my V12 heads i had regrind cams,smaller base circle, and got someplace(that a cant remember), a box full pads thicker than factory!

but i did not know 6.0L lash pads are smaller diameter,than 5.3L

maybe lighter weight, or a simple more plentiful pad from another engine ford engine!

whats sad for me when moving from florida to texas and in a hurry , i sold a box on 5.3 pads(over 100 pieces) of all kinds and sizes for $10.dollars.

also junked 3 complete V12s, got $75 for the bunch!

sometimes things change so fast you lose touch with reality.

but on a somber note, what in hell would do with that stuff today anyway.

just collect more dust. altho it had no realistic value back 15yrs ago, and now it is becoming of more value.

 

Interestingly the tappet for the 5.3 and 6.0 are listed as the same part number, but the shims are listed differently.

Exhaust valves are also same part number for 5.3 and 6.0. Inlet valves are different 6.0 have a machined section in the center see pics. I suspect this is just a CR adjustment.

 

On grinding shims: This is the only option you have as far as I know. Isky sends them to you .170 thick, and that is what you do. Jaguar never offered shims that thick. I have spoken with several tool and die makers, machinists, and grinding a piece or hardened steel doesn't effect it as long as it isn't super heated. I've done this before. Its a long slow process, but I keep a small bowl of water next to my bench grinder when I do this. I put the shim against the side of the wheel, and then drop it in the water. Its not fun, but it can be done. I asked how a shop does it, and for those that are set up for it, there evidently is a magnetic base that will hold the shim, and then is ground down slowly from there. I was told that they only take .001 at a time, but never cool the shim. That is about how much I take off at a time, and constantly check it with a micrometer.

 

I may can post pics at some point, but looking at the pics Warrjon sent, I have machined the combustion chamber down to the surface of the face on the intake side. It completely removed the "swirl" effect you see, and created a bowl all the way out to the gasket. I will be cc'ing them before long, and will know my exact compression ratio. From my calculator, I'm thinking in the low 9:1 range including the copper gaskets. On supercharging, from what I've read, the swirl design would just be in the way, lol. I doubt this engine will be much on economy though.

 

that brings to my memory, i made a small tool ,aluminum, 1" dia rod , and machined in the end a recess to hold the pad, and alum. draws heat awat quickly.

but i made it for holding the pad, worked great, for my 5.3, all thick ones needed to be ground thinner, but most fit by just measure and check clearance. (musical pads) DUH.

 

The local shop is a neighboring town has a shim grinder.

My only issue is - doing it by hand its very difficult to ensure the shim is ground flat

 

My knowledge of differences between 5.3l and 6.0 l V12:

6.0 block casting mounting flange for transmission has been modified to accept GM 4L80E four speed auto.

6.0 crankshaft made from forged Steel with increased throw for 78.5mm stroke.

6.0 cylinder liner 2mm shorter to provide clearance for can rod.

Bearing shells for 6.0 are graded sizes to reduce maximum clearance s by 20%

6.0 has different crankcase breather.

Pistons on 6.0 have gudgeon pin (wrist pin) in different place for increased stroke and 11:1 compression ratio.

6.0 cylinder heads have increased volume combustion chamber for compression ratio change.

6.0 has cold air intake above radiator for induction system.

6.0 has fuel injection pressure at nominal 3 bar whilst 5.3 fuel injection pressure is set at 2.5bar



Inlet valve on 6.0 is 0.6mm shorter stem.

6.0 camshaft profile modified (quietening ramps) and 0.025mm reduction in maximum lift to reduce valve train noise.

 

Paul ,good info about the 6.0L engine , especially the valve and cam info.

this question was raised on another forum,at the time nobody knew much about cam and valve train.

altho we had heard about early 6.0 cranks were forged steel later cranks were FORD Nodular cast cranks,, BUT im betting they are just as good as forged up to 750HP!

and i dont think anyone on this site has a 750HP car running at this time!!!

but good useful info never the less,, THANKS

 

I can tell you from experience it is very difficult to get shims ground flat the way I do it. But seeing as how I have more time than money (lololol no time anymore either), I choose to grind my own the way I do it, and have my micrometer constantly there checking it. I got it checked with a micrometer that goes down to tenths of thousandths, and was very close.

 

Other differences are

The 6.0L block can be drilled to accept the TH400, mine is.

Crank snout is different, no more dual keyway, it uses a Chev typeslip oin damper.

Injector rail is different with O'rings replacing the hoses.

The guy who will build my engine has an XJS pre-HE making 500hp NA and cruises at 300km/h, built for the Cannonball Run here in Aus. Oh it's a 6.0L 70 stroke 95 bore. He also has a NA 850hp V12 running in a boat.

I think 750hp in a road car is NUTS, my brother has a 67 Shelby GT500 making 800hp even though its easy to drive is also difficult, sneeze and the thing goes sideways.

450hp in a HE V12 is doable, look at the XJR15. Although my build will focus on HP under 5500rpm (ie Torque)

 

agree, 750HP on the street is dangerous/fun and easily out of control, wet roads,sand, debris,etc.

anything over 450HP becomes a hand full. but 750 has its bragging rights!

i do know i would(money and time dependent), build a realiable turbocharged JAG V12 , make a smooth 750/800HP betting good MPG also!

but as most here i'm still looking into an AUDI V12 Diesel , factory 500HP BUT 700 lbs.TORQUE.

without taking the engine apart ,reprogram ECU, and better Exhaust system, and inlet system, make a smooth ,economical, dependable 750HP(down low in the RPM range), 850 LBS.FT. of torque!
judging by the numbers cost of crazy head mods to an ANTIQUE Jag V12 , i know i'd be far better off !
and be the only XJS roadster with a Diesel engine, bragging rights again.

a HD built GM 4L80E, with a TCI 6 speed trans kit in it.

i do belive it would be less costly and more special.

 

just after posting my preferance for an AUDI V12 TDI engine,

YUP one shows up on e-bay , BUT i just may not be able to afford it, wife may talk divorce!

story of my life, honestly anytime i have wished for something it does come along, but not when i am serious enough to do.

damn i'm getting older, and now limited in cash flow, retired!!

someone should really buy this engine and make a very unusual XJS, i,m getting guys who want to put it in an old CHEVY ,65 Impala!!

betting it will show up in an american car soon!

 

I think the swirl allegedly created by this chamber is doubtful. IMHO its the large quench area and tight (for the day) squish that was most effective in burning lean mixtures.

I saw a pic David Vizard took of a single cylinder engine with transparent cylinder walls, yes you could see the combustion process.

It showed as the piston goes down the bore the swirl diminishes, and almost cease as the piston comes up on the compression stroke.

Swirl in the port is way more important to keep the fuel suspended. Too much swirl in the chamber showed the fuel thrown against the cylinder walls then as the piston comes up, the top ring wipes the fuel into the crevice.

Unshrouding valves the David Vizard way - Draw a circle around the valve 1.4D. So a 41mm valve draw a circle 57.4mm in diameter this is the shrouding envelope, removing metal outside this area will do nothing for geometric shrouding.

So keep the chamber as small as possible to unshroud the valve and dish the piston under the valves to lower CR.

This will keep the quench pad as large as possible and the squish tight, 1mm is as close as you can get. You could also dish the pistons to lower CR if needed.

 

I really appreciate the advice, but at this point I'm a little past that. I have milled the heads out unlike anything I've ever seen. I had talked about new pistons, cutting the pistons maybe. But after looking at cost vs value, and the fact that the liners and pistons had little to no wear, I decided to lower compression by cutting the heads. Cutting the pistons seemed my best option (still not too late), but at this point, I'm going to CC the heads, find my actual compression ratio, and go from there. With a 3.3L supercharger, I may have to stick with 4-6lbs of boost.

 

gene , it seems you have removed all the quench area(show pix?), and you will still have some swirl spin from the pocket, depends on piston top shape for quench and swirl!

like warron said, piston has to come close as possible to head without touching,for squish quench like .040 thou. but could still have an odd shaped bowl to lower compression #.

and most forced induction people say if you are not going to have at least 7 lbs boost ,

be waste of time and money,

proper hi comp. ratio, and head flow+ cams would be adequate, for N/A engines.

plus if only 4-5 boost you could easily go 10-1 ratio, and adjust tuning to suit things!

also quite often copper head gaskets in conjunction with open deck block, leak/weep around perimeter , sometimes have to add coolant each morning(been there,done that).