3.4 - Main bearing replacement with engine in ( Nigel Roskilly,
June 13, 2005
Jaguar's ignition timing settings for Saloon's are static numbers,
so there is no vacuum when the engine is off.† When you check
the timing dynamically with the engine running using a timing light,
you have to disconnect and plug the vacuum line and make sure
the idle speed is not higher than 500 rpm (usually not the case).
If the idle is high or the springs in the distributor are weak,
(they usually are), the advance will affect the idle setting and you
will wind up with retarded ignition timing.† It is better to look up
the Max advance number, in your case 5 + 26 = 31, and have someone
rev the engine to 3000 rpm while you check the timing with a light
(vacuum disconnected).† You can use an advance light or mark the
damper by measuring the 10 degree mark and doubling and tripling
it.† After you set the Max advance, if it is showing more than 5
BTDC at idle, say 12-15 degrees, then your springs are worn. You
will often hear people on this list saying their car doesn't run
right unless you set the timing 10 degrees advanced, it is usually
because the distributor is worn out and the idle is high enough
to bring in the advance.†
There is 4 crank degrees of slop in the spec for a ''new'' Lucas distributor, so the spec is really 27-31 BTDC.†
I can tell you from experience a hemi head does not make best power at 27 degrees.†
If your engine runs hot and you can only get lousy fuel, you may not be
able to run the optimum timing.†
The XK engine is a knock limited design and the optimum advance
figure varies with engine temp, air temp and octane.† The engine
will keep making more power if you advance the ignition, but you
will more than likely run out of octane before you get there.
The E-Type used the same 13 degree (dist) advance mechanism with a 10
degree static setting.† I have used those cams in the past and
they have a little more duration, which in theory should allow more
advance because they bleed off low speed compression.† If you
have 180 psi of cranking pressure, your milled head may be offsetting
this a bit. Cold air to the carbs is the best modification you
can make to allow you to run the best timing.
3.4.1 - ARP Con-Rod Bolts for the XK Engine ( Terry Handley,
September 19, 2001
The XK Jaguar has a nice long Forged Steel Con Rod & if your Shop say's
that to use the old bolts is OK, they are D...H.... & obviously don't know
much about building good engines, you do want a good engine ?
This is not some engine your building in your backyard to just go ticky
ticky down to the Supermarket, your paying a shop to do the job ?
There are bolts available from various sources but they don't fit XK Con
/Rods so well, they are generally too loose, some are ARP & or Similar Bolts
that have been Linished down so as to be able to be fitted by the DIY
backyarder or the ill equipped shop to an XK Con Rod.
I warned Listers about those bodged bolts some 2/3 years ago.
Don't be fooled tricked or conned, after building testing, racing XK
engines for over 35 years I believe the BEST BOLT FOR YOUR XK ENGINE is an
Ford 351/400 M V/8, ARP Part Number, AR154-6001. & it costs much less then a
Standard inferior Jaguar Bolt & much less then a Bodged Linished ARP Bolt.
There is some good information on ARP's homepage and also other places, read
about floppy fitting bolts and you will realise the advantages of using a
properly fitted ARP Bolt, it should not be hard even for the DIY Back Yarder
to deduce that a Bodged ARP Bolt is not going to be worth a Cracker & of no
advantage over a standard from Ford or Jaguar Con Rod Bolt.
OH! Yeah Get this for the record Ser,3 XJ6 Con Rod Bolts need to be torqued
to 45 Ft lbs, otherwise they do not clamp.
37 Ft lb torque is for earlier xk con rod bolts.
3.4.2 - Head stud replacement ( Paul Saltwick,
July 10, 2002
Question posted on the Saloons list:
Listers, the rebuilding of the engine on my 3.8 S-type is getting
close to being completed. The question to you all is, should I
replace the head bolts? and if so, should I go for the Racing
Quality Stud and Bolt kit on sale at XK's unlimited.
The head studs can be reused, but I recommend replacing them, especially if
there is any sign of corrosion. This is more important on the later 4.2 to
avoid serious disappointment. I haven't tried the XKS studs, but if they are
made by ARP, they should be good quality. Terry's also has uprated studs.
At this point, "new" 3.8 studs are probably made in someone's basement and at
least one vendor has sold studs with cut, rather than rolled threads, so ask
where they came from. Your engine should be fitted with four longer studs
for the lifting brackets, one of which (second row, exhaust side) is a
locating dowel with a thick waist. Some of the aftermarket studs do not have
this feature, which keeps the head from moving around. If you go for high
performance fasteners, you also need to increase the torque (usually up to
70ft/lbs) to take advantage of them.