[v12-engine] Head studs

Ok its time for me to get serious about building a new bottom end for my
engine. It keeps oiling up No 3 and 6 on the Rh side, so I figure the rings
are shot. I have rebuilt both heads not long ago.
So I am going to re ring and bearing my spare bottom end.
Problem is, the head studs are knackered!!!
We had to oxy cut them to get the heads off. I know, butchery at its worst.
Are stud sets available?
If so , from who? And hopefully in Aus.

Andrew Holley
77xjs

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Ok its time for me to get serious about building a new bottom end for my engine. It keeps oiling up No 3 and 6 on the Rh side, so I figure the rings are shot. I have rebuilt both heads not long ago. So I am going to re ring and bearing my spare bottom end. Problem is, the head studs are knackered!!!! We had to oxy cut them to get the heads off. I know, butchery at its worst. Are stud sets available? If so , from who? And hopefully in Aus.

Hey Andrew,

You might want to check with http://www.vicspiteri.com.au/frame.htm Under
Products–>Engine–>Head Studs. It says Chrome Moly set for the XK engines,
but you might call em up & inquire anyway.

Paul Kobres
85’ XJS
Columbia SC

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Is there an agreed opinion on a solution to corroded head studs in the V12?
(for example could coatings, sealing or o-rings help)

Is there a preferred option for a source of studs for a racing engine?
(is the standard Jag stud good enough? Are there aftermarket options (ARP
etc))

Is there an agreed solution to head sealing with adequate clamping force to
prevent problems in high capacity / power motors?

I’d be interested in the lists’ opinion.

Thanks
Mark

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In reply to a message from Mark Eaton sent Wed 13 Mar 2013:

Mark I used aftermarket chrome moly studs, but unfortunately the
company that supplied them is no longer trading. They are bright
zinc coated. I don’t think head stud corrosion is an issue on an
engine that is appropriately maintained with coolant inhibiter.
Such as yours will be.

Talking to Dave Silcock recently about head sealing, he maintains a
number of XK engine race cars with high compression. All use a
standard head gasket, and he considers O rings unnecessary. His own
4.5 litre 460hp XK motor is running 13.5:1 with no sealing issues.
You will be running less compression than an HE engine, Yes?–
The original message included these comments:

Is there an agreed opinion on a solution to corroded head studs in the V12?
(for example could coatings, sealing or o-rings help)
Is there a preferred option for a source of studs for a racing engine?
(is the standard Jag stud good enough? Are there aftermarket options (ARP
etc))
Is there an agreed solution to head sealing with adequate clamping force to
prevent problems in high capacity / power motors?
I’d be interested in the lists’ opinion.


Neville S1 XJ12, Megasquirt ECU
Christchurch, New Zealand
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1 Like

Is there an agreed opinion on a solution to corroded head studs in the
V12? (for example could coatings, sealing or o-rings help)

What WAS agreed, ten years ago now, was that corroded head studs
wasn’t even an issue with the V12. It had been a horrible issue with
the XK so everyone presumed it’d be an issue with the V12, but time
and again people pulled their heads off and found the studs to be in
good shape, no real call for replacement.

It’s ten years later now, though. Perhaps in the additional age
comes more issues with stud corrosion.

I’ll bet the answer is still that the best way to protect those studs
is to change the coolant regularly. You DON’T want to coat them,
because no coating is perfect and any void or crack in the coating
will concentrate the corrosion at that spot. It’s better to be
distributed over the entire stud.

The other rule of thumb, of course, is no Barr’s Leaks. It’s
commonly agreed that it’s the Barr’s Leaks that locks those heads to
the studs and makes them a b**ch to get off. Whatever the solids are
in Barr’s Leaks, they rise up into the stud passages in the head and
form a tapered plug that grabs the stud and won’t let go when you’re
trying to lift that head. But that’s not really a stud corrosion
issue, that’s foreign material.

Is there a preferred option for a source of studs for a racing engine?
(is the standard Jag stud good enough? Are there aftermarket options
(ARP etc))

I think that anyone seeking higher strength in the head studs
generally goes for a larger diameter stud. The OEM studs are high
grade, you can’t do THAT much better while retaining the stock size.

Is there an agreed solution to head sealing with adequate clamping
force to prevent problems in high capacity / power motors?

You might want to venture over to the racing@jag-lovers.org list.

– Kirbert

Visit the Jag Lovers homepage at http://www.jag-lovers.org for exciting services and resources including Photo Albums, Event Diary / Calendar, On Line Books and more !On 14 Mar 2013 at 11:24, Mark Eaton wrote:

In reply to a message from Mark Eaton sent Wed 13 Mar 2013:

For my race engines I always ‘‘Timesert’’ the block and use the std
studs. You will strip the block before the stud breaks.–
The original message included these comments:

Is there a preferred option for a source of studs for a racing engine?
(is the standard Jag stud good enough? Are there aftermarket options (ARP
etc))


850225/679,1E21003,2W2001BW,JNAEY3AC100218,SAJNV4841KC156072
HEIDELBERG HEIGHTS, Australia
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For my race engines I always ‘‘Timesert’’ the block and use the std
studs. You will strip the block before the stud breaks.

Wow. I suppose Timeserting the block would also be a good idea for a
race engine that gets torn down on a regular basis, as repeated
screwing and unscrewing doesn’t do much good for threads in aluminum.

For the regular Jaguar owner, is there any good reason to timesert
the block BEFORE you strip out a stud hole or two? Or can you just
wait until the problem arises?

– Kirbert

Visit the Jag Lovers homepage at http://www.jag-lovers.org for exciting services and resources including Photo Albums, Event Diary / Calendar, On Line Books and more !On 14 Mar 2013 at 14:38, Norman LUTZ wrote:

In reply to a message from Kirbert sent Thu 14 Mar 2013:

I now use ‘‘timeserts’’ on all V12 engine rebuilds because I find it
quicker to remove the heads if you over torque the studs and strip
the threads from the block.–
The original message included these comments:

For the regular Jaguar owner, is there any good reason to timesert
the block BEFORE you strip out a stud hole or two? Or can you just
wait until the problem arises?


850225/679,1E21003,2W2001BW,JNAEY3AC100218,SAJNV4841KC156072
HEIDELBERG HEIGHTS, Australia
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In reply to a message from Kirbert sent Thu 14 Mar 2013:

I’m confused here Norm.

I looked up the Timesert product. Interesting. The site
discusses the use of their product to repair damaged threads.

Why would you use them in your race engines ? Is Kirby right
in saying that it saves the block on frequent tear downs,
but is that what you do and why would you remove the studs
on a tear down ?

Are you spreading the stress of the stud threads over more
aluminum by using these inserts ?

Would that not be the same as drilling out the block for a
8/16’’ stud up from stock 7/16’’ stud ?

After looking at my block I also wonder if you do some
machining of the block in order for the flange on the
timesert to lie flush with the block ?

Whats the thinking here Norm ?–
The original message included these comments:

For my race engines I always ‘‘Timesert’’ the block and use the std
studs. You will strip the block before the stud breaks.
For the regular Jaguar owner, is there any good reason to timesert
the block BEFORE you strip out a stud hole or two? Or can you just
wait until the problem arises?


1987 XJ-S, 1988 XJ-S Tremec TK500. AJ6 Torque kit
Toronto, Canada
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I now use ‘‘timeserts’’ on all V12 engine rebuilds because I find it
quicker to remove the heads if you over torque the studs and strip the
threads from the block.

Lemme get this straight: Your PROCEDURE for removing the heads is to
torque the nuts until the studs pull out of the block? You don’t
even TRY removing the nuts and lifting the heads off? You don’t even
TRY unscrewing the studs?

And are you implying that virtually ALL V12 heads will get stuck
onto the studs when you’re trying to remove them? Even if the owner
hasn’t been using Barr’s Leaks?

And what happens if you run across an engine that someone has already
timeserted? Heck, what do you do if you need to go back into an
engine that YOU timeserted? Do you just remove the nuts and lift the
heads? Do they get stuck?

And, just outta curiosity: How much torque does it take to pull the
studs out of the block? Do you even measure, or do you just crank
until they come loose?

– Kirbert

Visit the Jag Lovers homepage at http://www.jag-lovers.org for exciting services and resources including Photo Albums, Event Diary / Calendar, On Line Books and more !On 16 Mar 2013 at 18:51, Norman LUTZ wrote:

In reply to a message from Repairman sent Sat 16 Mar 2013:

They don’t only repair, they increase the allowable thread load in
the block by increasing the thread size. equivalent to increasing
the studs to 1/2’’.
The insert tool automatically machines the block to recess the
insert into the block.–
The original message included these comments:

Are you spreading the stress of the stud threads over more
aluminum by using these inserts ?
Would that not be the same as drilling out the block for a
8/16’’ stud up from stock 7/16’’ stud ?
After looking at my block I also wonder if you do some
machining of the block in order for the flange on the
timesert to lie flush with the block ?


850225/679,1E21003,2W2001BW,JNAEY3AC100218,SAJNV4841KC156072
HEIDELBERG HEIGHTS, Australia
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In reply to a message from Norman LUTZ sent Sun 17 Mar 2013:

I have used Timeserts for over 20yrs, and yes,somtimes they
are a great, saved my a$s more than once.

for an expensive race engine(especially aluminum
castings), and problem places OK, but for V12 jag head
studs, on a close to stock engine, I think it would be over
kill and waste of money, if anything a set of good ARP or
like, installed properly, would more than surfice.

adding to this thread,Grp44 said head gasket sealing is
what took some long race wins,away from them,and they used
all available knowledge of the era.

a quick scenario; just say you have a small coolant loss
for each race lap,like couple table spoons per lap, after a
some hard laps, you will be down on coolant and overheating
becomes a problem, you lose!

on one of my shop engine builds,not V12) we machined a
groove up into the head, and cut the top of the block,but
not the liners,and recessed the liners into the grooves,with
a flat copper ring,not Oring, open deck blk, ran OK,but a
lot off work.

engine was highly turbocharged 4cyl, 2L at over 800hp. and
thats far from the limit of it. it topped over 1200hp before
unravelling, on a 1900lb car,YUP it was fast.

hey, repairman what kind of HP you shooting for?
N/A or forced induction,NOS etc?–
The original message included these comments:

They don’t only repair, they increase the allowable thread load in
the block by increasing the thread size. equivalent to increasing
the studs to 1/2’’.
The insert tool automatically machines the block to recess the
insert into the block.


Ronbros
daytona fl. / Austin TX., United States
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In reply to a message from Norman LUTZ sent Sun 17 Mar 2013:

and today, if I were going for a serious HP build, id use the
Gas filled O-ring seals! expand and contract with temps and
pressures.–
The original message included these comments:

Are you spreading the stress of the stud threads over more
aluminum by using these inserts ?


Ronbros
daytona fl. / Austin TX., United States
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In reply to a message from Ronbros sent Sun 17 Mar 2013:

Frankly Ron, replacing the stock studs with ARP is a waste of
money. The weakest link here is the block, you’ll pull the studs
out before they break.
The 6 litre Kit I produce oncreases the bore to 95mm, this
increases stud loading by more than 25%. But using ‘‘Timeserts’’ with
std studs I have never had a stud or block problem.–
The original message included these comments:

for an expensive race engine(especially aluminum
castings), and problem places OK, but for V12 jag head
studs, on a close to stock engine, I think it would be over
kill and waste of money, if anything a set of good ARP or
like, installed properly, would more than surfice.


850225/679,1E21003,2W2001BW,JNAEY3AC100218,SAJNV4841KC156072
HEIDELBERG HEIGHTS, Australia
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In reply to a message from Ronbros sent Sun 17 Mar 2013:

RonBros,

I’m taking my time re-building a stock 5.3 back to factory
spec. The budget is open for anything, all within reason. I
just want a safe reliable 5.3

I dismantled two v-12’s into over a hundred numbered plastic
bags, now putting it back together

Not looking to build a muscle car, 300HP is fine

Timeserts sounds like a great idea after I’ve damaged the
existing threads, so that idea can wait

Regarding ARP studs, ARP does not make studs for the XJ-S, I
emailed them the specs on the studs, they have nothing.

On a sidebar, ‘‘Made in the USA’’ stainless 316 bolts vs.
‘‘Preferred Vendor’’ 316 bolts are 5x more expensive ARP bolts
are actually cheaper than ‘‘Made in the USA’’, and are made in
the USA. So, all motor bolts are slowly being replaced with
ARP 12 Points. Not cheap, but all made in North America, and
I like the look.

I’m about to replace all my head studs with new, why,
because I then have a known standard, all will have good
threads, and be straight, nothing stretched.

My amazement of building the motor is just how ‘out of spec’
everything is, on both motors. My good motor oil pump was
way over the max clearance of 0.005, the housing all scored,
used the second motors pump, that was on spec. Maybe this is
why some people have low oil pressure…

Dizzies, have 3, all three have issues, again , the good one
has a tremendous amount of play on rotation and has a gritty
movement, the other the dizzy lower gear is pooched, on the
other the vac advance was corroded and just cracked.

Balancing the rotational mass this week. As you know the
1700(ish) gram mass has to be within 1 gram. My data with
cleaned everything gives a spread of 18 gram from the
heaviest to the lightest mass grouping. WTF.

The list goes on, just having fun with retirement…–
The original message included these comments:

castings), and problem places OK, but for V12 jag head
studs, on a close to stock engine, I think it would be over
kill and waste of money, if anything a set of good ARP or
like, installed properly, would more than surfice.


1987 XJ-S, 1988 XJ-S Tremec TK500. AJ6 Torque kit
Toronto, Canada
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In reply to a message from Kirbert sent Sun 17 Mar 2013:

In a word YES!
I’ve been rebuilding V12’s for nearly 40 years and any engine that
done 100K plus, 9 times out of 10, will have the heads seized on
the studs. Even if the heads do come off, the chances are some if
not most of the studs will be corroded in the block and will tear
the threads on removal.
So I don’t F*** around. the quickest and cheapest way is to ‘‘torque’’
the studs out, which means you don’t even have to drill the block,
you can run the tap straight down.
As for previously rebuilt engines, they are pretty obvious and as
for being ‘‘timeserted’’, highly unlikely. Most people have never
heard of them.
An Impact wrench has no consience!–
The original message included these comments:

Lemme get this straight: Your PROCEDURE for removing the heads is to
torque the nuts until the studs pull out of the block? You don’t
even TRY removing the nuts and lifting the heads off? You don’t even
TRY unscrewing the studs?
And are you implying that virtually ALL V12 heads will get stuck
onto the studs when you’re trying to remove them? Even if the owner
hasn’t been using Barr’s Leaks?


850225/679,1E21003,2W2001BW,JNAEY3AC100218,SAJNV4841KC156072
HEIDELBERG HEIGHTS, Australia
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In a word YES!

OK, if I ever get around to issuing another revision of the Book,
that one’s going in it! There has certainly been a great deal of
grousing over the years about problems getting the V12 heads off, but
AFAIK nobody has ever suggested just going ahead and stripping out
the studs and timeserting the block when reassembling. Considering
just how much trouble people have gone through getting those heads
off, I’m sure some of them would appreciate the suggestion.

I presume that, if you try to remove the heads the normal way and run
into trouble, you can just set them back down and reinstall the nuts
(perhaps with anti-seize on the threads) and THEN tighten the nuts
until the studs pull out?

BTW, do you reuse those studs? Or do you consider that particular
set ruined and install a new set with the timeserts?

– Kirbert

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In reply to a message from Norman LUTZ sent Sun 17 Mar 2013:

Norman

This sounds much easier than building a head puller! I have
one question, please:

Are the stripped holes left in the block sufficiently
centralised that, when timeserted, the new studs will screw
into sufficiently accurate locations that the heads go on OK
afterwards, with no problems?

Thanks–
The original message included these comments:

So I don’t F*** around. the quickest and cheapest way is to ‘‘torque’’
the studs out, which means you don’t even have to drill the block,
you can run the tap straight down.


HE V12
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In reply to a message from JagJean sent Mon 18 Mar 2013:

When I first sttarted rebuilding V12’s, I struck an engine that
took me nearly 3 weeks to get the heads off without a head puller.
That’s when I started pulling the studs by over torquing and
inserting a threaded plug for the repair.
Then I discoverd ‘‘Timeserts’’ which made the job so much easier.
Stripping the hole in the block will not alter their position.–
The original message included these comments:

Are the stripped holes left in the block sufficiently
centralised that, when timeserted, the new studs will screw
into sufficiently accurate locations that the heads go on OK
afterwards, with no problems?


850225/679,1E21003,2W2001BW,JNAEY3AC100218,SAJNV4841KC156072
ROSANNA, Australia
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In reply to a message from Kirbert sent Sun 17 Mar 2013:

If the shank of the stud is not too corroded I reuse them–
The original message included these comments:

BTW, do you reuse those studs? Or do you consider that particular
set ruined and install a new set with the timeserts?


850225/679,1E21003,2W2001BW,JNAEY3AC100218,SAJNV4841KC156072
ROSANNA, Australia
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