12-29-97
Written by: Reg Riemer of SONiC { Supra Owners Network in Canada}
Information provided is given free of charge in good faith without
prejudice.
Feel free to distribute in original form. Do not alter or modify this
document.
FILE NAME: METALHGv5.txt
TABLE OF CONTENTS:
1. INTRODUCTION
2. INFORMATION ON HKS METAL HEAD GASKETS
12-29-97
SONiC TECH NOTE SERIES:
HKS METAL HEAD GASKETS, ENGINE PREPARATION & MACHINE WORK
Information provided is given free of charge in good faith without
prejudice.
Feel free to distribute in original form. Do not alter or modify this
document.
TABLE OF CONTENTS:
1. INTRODUCTION
2. INFORMATION ON HKS METAL HEAD GASKETS
3. THE THREE TYPES OF HKS GASKETS
4. QUESTIONS ABOUT USING AN HKS METAL GASKET
5. HOW TO FIND A MACHINE SHOP THAT CAN HELP YOU
6. LAPPING! THE SOLUTION TO BAD MACHINE WORK
7. SONiC LAPPING TOOLS CAN LAP AN ENGINE BLOCK IN THE CAR
8. USING THE SONiC LAPPING TOOL ON A NEW ENGINE REBUILD
9. CYLINDER HEAD WARPAGE RELATING TO MACHINE WORK
10. CONCLUSION
1. INTRODUCTION
When people go to work on a head gasket replacement job, they sometimes tend
to
rush the engine back together. Rushing the engine together is the worst
thing to do.
When an engine is open be sure to take the necessary time to look for all
the things
that need to be looked at. This tech note covers all the areas that you need
to be
aware of, read it over carefully.
We will discuss several important areas surrounding head gasket repair
procedures
and metal head gaskets; the three different types of HKS metal gaskets
available for
popular Japanese engines, how to determine if your engine will need machine
work,
how to find a good machine shop in your local area, how to be sure the work
your
shop does is suitable to allow the use of a metal head gasket, and SONiC
lapping
tools and techniques to allow repair of damaged block or bad machine work.
2. INFORMATION ON HKS METAL HEAD GASKETS
Over the years of using HKS metal head gaskets, I have never seen any
quality
problems with them. They are without question the best money can buy. Any of
the
HKS gaskets will last for the life of the engine if they are installed into
an engine that
has been correctly prepared.
When you purchase a gasket always make sure the dealer you buy it from
packages
it correctly for shipping. It is very easy to bend these gaskets when they
are
shipped.
HKS metal gaskets come with a special type of rubber coating applied to the
gaskets
outer surfaces. This coating gives the gasket a good cold seal for when the
engine is
cold started after gasket replacement work is complete. As the engine heats
and
cools this coating also allows the metal gasket to settle into place between
the cast
iron engine block and aluminum cylinder head.
Metal gaskets will not cover existing problems and damage to surface finish
or bad
preparation work of the engines cylinder head and block deck surfaces. I
have seen
a number of engines that were just back from the machine shop and the
machine
finish on the head and block deck were not smooth enough to allow the use of
a
metal head gasket.
3. THE THREE TYPES OF HKS GASKETS
There are three different types of HKS metal head gaskets. They are listed
as
follows in order of popularity and cost.
1. Bead Type { least expensive}
2. Stopper type { expensive design}
3. Grommet type { most expensive design}
*BEAD TYPE gasket is the most common type sold and used in the Toyota
engines
in our car club. This gasket is inexpensive and delivers very good
performance and
will last the life of your engine when installed correctly into an engine
that is
correctly prepared for the gasket.
* STOPPER TYPE gasket is the best gasket you can buy from HKS or any
manufacturer. It is also the most expensive gasket design you can buy. This
is
because the manufacturing process used to produce this gasket is more
complex as
are its materials, therefore the cost to manufacture it is higher than the
bead type
gasket.
* GROMMET TYPE is not a very common type of gasket and is presently only
used
in a few types of engines. If more of the GROMMET TYPE gaskets become
available,
I'm sure we will learn more about them.
The three types of HKS gaskets are all designed differently and therefore
require
unique manufacturing procedures and materials to be produced. The purchase
prices of the gaskets will vary considerably depending on the gasket type
you choose
and the thickness of the gasket required for your particular engine
application.
As any of the HKS gasket types get thicker, there are more layers of metal
in the
gasket design. The 2mm gasket has more metal layers than a 1mm and a 3mm
will
have more than the 2 mm. As each layer adds an extra sealing surface, it is
my
belief that the fewer layers in the gasket the better. I have learned that
with
mechanical equipment the simplest design is always the easiest to work with
and the
most reliable!
All three of the gasket designs work very well. The difference between them
is with
the engine application they are to be used. The condition of the engine
components
will determine how thick the gasket must be. Remember that every 40
thousands of
an inch is equal to 1 millimeter.
Example:
If your engine has not received any machine work before and a machine shop
removes 10 thou from your cylinder head and 10 thou from the block deck the
shop
will have removed a total of 20 thou from your engines components. From this
it
follows that 20 thou is about .5 mm. Lets assume that the stock gasket in
your
engine was 1.0 mm. Then to retain the stock compression ratio of your engine
after
the machine work you will require a 1.5mm head gasket.
Be sure to ask your HKS dealer for help before purchasing a metal gasket for
your
engine. You will need to know the past condition of your engine as well as
the
machine work it now requires before you can buy the correct gasket.
As a rule it is best to use the thinnest gasket you can. Remember that the
correct
gasket thickness for your engine is based on the machine work done to the
engine,
not on what your friends think you should run.
4. QUESTIONS ABOUT USING AN HKS METAL GASKET
The following question is one that I have received from many performance car
owners.
>?
> Hi Reg
>
> I know you are real busy and all but please just answer my one question?
> When changing the old head gasket to new HKS metal head gasket, do I
> need to do any other work on the engine like resurfacing the block or
> can I just replace the head gasket.
>
>Please get back to me ASAP so I can start work on the bad head gasket in my
93
Talon
> TSI all wheel drive turbo.
> Thanks
> ->
John Smith
> Corning, NY
Today's high tech engines from Toyota, Mitsubishi, Honda, and Mazda come
from the
factory with cylinder head and block deck machine finishes that are
perfectly suitable
for use with HKS metal shim head gaskets. The problem is this factory finish
is next
to impossible to duplicate in the real world should you require machine work
to be
done on your engine.
Some SONiC members who have had machine work done to their engine when they
installed a metal head gasket have experienced problems with combustion
gasses
leaking past the head gasket into the coolant jackets or oiling system. The
marks
from the machine tools can leave a pattern of fine grooves, on the engine
cylinder
head and deck surfaces. This rough textured surface allows the engines high-
pressure combustion gasses to fizz through past the metal gasket.
Because this smooth factory finish is very hard to have reproduced by the
machine
shops around the country several things must be kept in mind when machine
work is
done to your engine's deck and head surfaces.
They usually never admit it, but try as they might, many reputable machine
shops
have major problems obtaining a smooth enough finish to allow the use of a
metal
shim gasket. The reason for this is that they simply don't have good enough
equipment, procedures, or technicians to achieve an acceptable finish to
provide a
tight seal when using a metal head gasket.
Unless the shop is familiar with doing work of this caliber, they will not
understand
why you want a better job than what they have done. I have seen machine
finishes
bad enough to cause sealing problems when using a stock composite gasket!
Because of this area of concern, I would only recommend that the engine
block deck
only be machined (resurfaced) if there is damage to the deck surface caused
by the
compression rings of the old head gasket. However, usually you will need to
resurface the alloy cylinder head because the compression rings of the stock
gasket
bite into the alloy surface of the cylinder head.
When we are talking about damage to the block or cylinder head finish we are
talking about a very small amount of damage around the cylinder bores. This
is the
area where the compression rings of the stock gasket were compressed between
the
block deck and the head. This damage is not extremely visible, it may take a
closer
inspection to see it. Any damage in this area of three thousands of an inch
or more
is too much when use of a metal gasket is intended. The compression ring
area
around the combustion chambers of the gasket is the area of highest cylinder
pressure.
5. HOW TO FIND A MACHINE SHOP THAT CAN HELP YOU
To find a solution to this machine finish problem I did a lot of research
into the
machine tools and the procedures that most shops can provide. As we have
learned,
there is only a small percentage of shops that can produce a good enough
machine
finish to allow the metal shim gasket to work as it was designed to.
Shipping engine blocks and cylinder heads around the country so that a
renowned
good shop can do the work is counter productive. So lets talk about how you
can
find a good local shop that can provide quality work on your engine. I will
also cover
how to fix poor quality machine work already done to your engine, by using
some
special Lapping tools that I 'm having manufactured.
To find your quality machine shop you will need to ask the technical people
that work
at the shop if they produce any racing engines for the drag strip or road
racing.
Frequently shops that produce high volume production of general automotive
machine work will not be suitable for your needs. Ask around town to find
out where
most of the people who build race engines get their machine work done. This
approach will usually find you a good quality shop.
As an example, I found a local shop in my area that can produce a fantastic
machine
finish. This shop happens to be an oil field machine shop located in
Calgary, Canada.
They deal with many of the large natural gas and oil patch companies. Their
specialty is smooth flat finishes on valves and other gas/oil equipment. So
this is
another area you could look for a shop in your local area.
The shop I found can make the surface of the block and head so smooth and
flat
that, in the words of the owner. "With our quality finish you could run the
engine
without any gasket at all if you wanted to". I don't think I want to try
this but his
point was well taken. A good finish will provide a perfect seal in an engine
with a
metal head gasket.
6. LAPPING! THE SOLUTION TO BAD MACHINE WORK
The machine shop I located in my local area also showed me a custom made
4-foot
long lapping bench. With this bench you can make any machined flat surface
perfectly smooth and totally flat.
Lapping is a process that involves rubbing the cylinder head or engine block
over a
perfectly flat specially machined steel disk made of a special alloy
material. Before
the lapping procedure is started, the lapping bench is coated with a special
SSCC
compound. This compound allows the head or block to be moved over bench
surface
following a special pattern.
Lapping can remove enough material to clean up damaged areas or just add a
quick
polish to an already smooth surface. As much material as required can be
lapped off
the surface of the part. When a part is being lapped { polished} down to an
exacting
finish any errors in the previous machine work such as flatness and surface
finish will
begin to appear. Areas where the machine tools dive in or cut to deep will
start to
show up like a sore thumb. The lapping procedure is continued until all this
evidence
is removed.
I have used this lapping procedure on several Toyota 7M-GTE Modified engines
with
fantastic results. The finish the lapping tool gives is better than what
comes from
the factory!
You may ask, "Reg, as it's already hard enough to find a good machine shop
in my
small town, it is going to be next to impossible to find a lapping bench
like this.
What is your point with all this?"
I decided to take the ball into my own hands and solve this problem for
anyone that
needs a solution. Based on using my shops procedure for lapping a finish, I
have
come up with a new idea! I contracted this shop to manufacture me a smaller
version of their full sized lapping bench as well as a portable full sized
version just
like theirs.
These new lapping tools are now available for sale to any shop or person
that needs
to prepare the finish on their engine blocks deck or newly cut cylinder
head. :-) The
SONiC lapping tools are available in two sizes:
-*The small sized lapping tool, available as part number # Lapkit sm -1 is
an
engine in the car block deck lapping tool disc that comes with the special
SSCC
lapping compound. An option for this kit is 14 each, 12mm x 1.25 pitch hex
head
set screws. The set screws are used to plug the head bolt holes in the block
deck.
Lapping tool kit with compound is priced at $249.00 US plus shipping and
handling.
-* Also available for shops with intent to finish many cylinder heads and
engine
blocks is SONiC part number Lapkit big-1 this lapping bench cannot be used
in the
engine bay. It is very large and heavy, 350 lbs. For more info on this,
email Reg at
[EMAIL PROTECTED] put Lapkit in the subject of your letter. Full
instructions for
the lapping procedure are included with all SONiC Lapkits.
7. SONiC LAPPING TOOLS CAN LAP AN ENGINE BLOCK IN THE CAR
By using this new SONiC lapping tool it is now possible to lap the deck
surface of the
engine when the engine is still bolted up in the car. Because this tool is
smaller in
diameter than the large bench it is a little trickier to use but with extra
care following
the procedure I have written for using this SONiC lapping tool the results
are the
same. The entire deck surface comes up smoother than it was when it came
from
the factory.
If the engine in your car is in good overall shape but has a damaged deck
surface
there is now a good alternative repair to completely removing the block
rebuilding it
and decking it. By using the small SONiC lapping tool with the SSCC compound
along with diligence the engine deck surface can be lapped back into
spanking new
condition. The same tool can also be used to smooth the bad machined finish
on the
cylinder head.
This is how the small tool is used on an engine block deck that is in the
cars engine
bay:
When using the small lapping tool on any engine block still in the car, a
thick
grease coating is put into the engine bores and oil galleries to keep any
existing dirt
from entering during lapping procedure with the Lapkit sm -1. As the SSCC
lapping
compound is quite thick and sticky it will not run down into the engine
bores carrying
with it any lapped metal, the grease in the bores is just a precaution.
There is not a
big danger of any contamination and clean up after the lapping procedure is
quite
easy.
RTV Silicone can also be used to plug oil gallery holes to keep them free of
any
residual SSCC compound mixed with block metal. If you use the optional 10mm
x
12mm 1.25 pitch set screw in the head bolt holes no compound will enter the
bolt
holes, thereby making this clean up area quick and easy work. These are
available
from most fastener sales counters or with your lapping kit at an extra cost.
The
ones I purchased were about $3.00 each so there must be a better place to
buy
them, I will look into this. If you are only doing the one engine, you may
opt to
clean the holes out one by one rather than spend the money on the setscrews.
After all the prep work and lapping is done the grease and silicone is
removed. The
block will look better than new. If the damaged areas are very bad you can
save
some lapping work by using an epoxy metal { JB weld} compound on the deep
very
bad areas before you lap it. Let the compound cure fully before you lap the
surface.
We have successfully lapped up to five thousands of an inch from the top of
a 7MGTE
block. Lapping out this much metal takes a bit of time but the results are
worth
the effort.
If JB weld was used to fill some of the badly damaged areas you must install
the
correctly prepared cylinder head onto the correctly prepared block using
only the 1.2
mm or 2.0 mm HKS bead type gasket. Follow the torque specs and pattern for
your
type of engine. As the HKS bead type gaskets do not have any high load areas
around the bore holes, this gasket is basically just a multi layer flat
shim. The load
from the head bolts is distributed equally along the surface of the deck,
hence the JB
weld works perfectly in this application and the engine will run forever if
this
procedure is done correctly.
8. USING THE SONiC LAPPING TOOL ON A NEW ENGINE REBUILD
If you are building a new engine you will want to clean up the new machine
finish on
your block and cylinder head, especially if the machine work looks too
rough. The
lapping process will move along much faster when it is used on a freshly
machined
surface. The machining should have removed enough material to smooth out the
damaged areas, therefore the lapping is only touching up the newly machined
surfaces.
As the engine is not in the car, silicone or greasing the engines oil holes,
bolt holes
or piston bores is not required. These areas will all be cleaned by the shop
when
they finish the other machine work.
The best order to have the machine work done on your new engine block is as
follows;
* Deck engine block with machine tools.
* Bore or hone engine bores.
* Lap deck with lapping tool.
* Clean entire engine block.
9. CYLINDER HEAD WARPAGE RELATING TO MACHINE WORK
When the time comes to work on your overhead cam engines aluminum cylinder
head there will be a number of decisions to make. You must find a good
machine
shop as discussed above. Be careful if the shop tells you they cannot
machine it and
you should not do this. Sometimes they are correct and in other cases they
may be
dead wrong. I wish this process was easier to explain, its not.
Cylinder Head Warpage
I hope that this section will help explain some of the thought process that
must go
into the decision of: Should I cut the head surface or leave it? Should I
try to have
the head straightened or leave it alone? Do I have to replace the cylinder
head with
a new one from Toyota or find another used cylinder head to have check out?
Don't pay cash for a used head until it checks out. Most reputable salvage
yards and
parts dealers will allow you to have the head examined by the shop of your
choice. If
they will not let you do this take your business somewhere else. It would be
an easy
big money business to be selling scrap aluminum for three hundred dollars a
bar.
Valve guides in the 7M engines seldom need to be replaced. If the shop you
are
dealing with says you need new ones you should question this!
To determine if your cylinder head is suitable to machine you must have a
good
understanding of the following test procedures, and the thought process
relating to
warpage. If you do not understand the methods of the testing, that's ok,
leave this
to your machine shop. However it is important that you understand the
concept of
what I am trying to explain. Read on as I will try to explain some of this
below. I
would recommend that you print this file so you can circle areas you want to
ask
questions about.
Remember that the head is not just warped at the deck where you measure it,
the
entire head is warped along with the deck. This means that the ports, valve
cover
gasket seal area as well as the cam saddles { what the cams spin in} are all
warped
x.x thousands of an inch. Following this idea if you have say 10 thou
warpage in the
deck surface when you measure it, the cam saddles should also have this 10
thou
warpage if the head has not been machined before. If you bolt the warped
head back
on the engine and torque it down this will pull the head straight again
providing your
block deck surface is flat. Think of it as a banana on a table, if you push
the banana
flat to the table it will look straight. When you let the banana go it will
look curved
again.
Now lets consider what happens if you cut the 10 thou of the bottom of the
head or
the banana! The deck surface of the head is now perfectly flat, but the cam
saddles,
and basically the entire head is still warped 10 thou. The banana is still
curved but it
has one side that is flat. This is ok as long as the cams still turn
smoothly in the head
when you have it bolted down to the engine.
Inspect the cylinder head for warpage in the deck and cam saddles. If the
deck is
warped less or more than the cam saddles you have a head that has already
been
machined at least once. If the head has not been machined before you will be
able to
tell because the warpage will be the same amount and in the same direction
on the
cylinder head deck surface and the cam saddles. It was all straight at some
point in
time. Because an in line 6 is a long engine a small amount of warpage is
normal.
Carefully inspect the deck surface of the cylinder head for any compression
ring
grooves left by the gasket that are deeper than 5 thou maximum. The engine
block
must also be inspected very closely for grooves in the block surface. If
there are
marks in the deck surface of the block they will almost always be on the
exhaust side
of the deck surface. If they are deeper than 3 thou you should have the deck
of the
block machined as well to get a better than new repair (see above sections
in this
tech note). Remember to have your timing cover machined along with the
block, it
also must be machined down to the height of the deck surface. The shop will
bolt it
to the block and cut them together.
10. CONCLUSION
Remember, if you do have the head and block machined and you want to use a
metal head gasket be aware that the finish of the machine work is very
critical to
getting the gasket to work correctly. If you use a lapping tool on this
fresh cut rough
finish you will have a perfect gasket surface.
The new style Toyota stock gasket is not as sensitive to block finish and
small
irregularity but it will also leak if the finish is too rough. The new style
stock gasket
can tolerate about 3 thousandths of an inch of groove damage.
I hope this answers some of the questions regarding HKS metal cylinder head
gaskets and engine preparation.
Regards
Reg Riemer
1997
To listen to the show archives go to link
http://acbradio.org/handyman.html
or
ftp://ftp.acbradio.org/acbradio-archives/handyman/
The Pod Cast address for the Blind Handy Man Show is.
http://www.acbradio.org/news/xml/podcast.php?pgm=saturday
The Pod Cast address for the Cooking In The Dark Show is.
http://www.gcast.com/u/cookingindark/main.xml
Visit the new archives page at the following address
http://www.mail-archive.com/[email protected]/
For a complete list of email commands pertaining to the Blind Handy Man list
just send a blank message to:
[EMAIL PROTECTED]
Yahoo! Groups Links
<*> To visit your group on the web, go to:
http://groups.yahoo.com/group/blindhandyman/
<*> Your email settings:
Individual Email | Traditional
<*> To change settings online go to:
http://groups.yahoo.com/group/blindhandyman/join
(Yahoo! ID required)
<*> To change settings via email:
mailto:[EMAIL PROTECTED]
mailto:[EMAIL PROTECTED]
<*> To unsubscribe from this group, send an email to:
[EMAIL PROTECTED]
<*> Your use of Yahoo! Groups is subject to:
http://docs.yahoo.com/info/terms/
