canadian
sy in progress
since my first post about intakes in the tech section didn't get very much input i figured i'd put the one about heads in here. hopefully you guys can help me out (jwaller, you out there?). here's what i have come up with so far, feel free to add information tell me where i'm way off since i pulled most of this stuff outta my ass.... 
since my first post about intakes in the tech section didn't get very much input i figured i'd put the one about heads in here. hopefully you guys can help me out (jwaller, you out there?). here's what i have come up with so far, feel free to add information tell me where i'm way off since i pulled most of this stuff outta my ass....
Heads
-----
Since 1991, GM has made several advances in head design that are superior
to the ones used on Syclones and Typhoons. The most popular ones are the
L35 (1992 - 1995?) and Vortec (1996+?) heads. There are other high dollar
aluminum and race designed units, but those are usually out of the price
range of the average owner and some won't work with the stock headers due
to their angle plug design.
When it comes to flow numbers, I found this post from the SyTY mailing list
archives:
http://www.syty.org/archives/syty/0004/msg01215.html
Ok with all the talk of heads and air flow numbers. Idug up some info from
awhile back
Intake at .500 lift at 28" water
LB4 stock SY heads 165 cfm
1995down L35 heads stock 193cfm
1995down L35 heads minor porting 211cfm (at 24" water)
1996 up vortec head possibly 250cfm
1996 up ported vortec head 270cfm
brodix -8head stock 240cfm
brodix -8head ported 285cfm
brodix -10head stock 253cfm
brodix -10head ported 289cfm
As you can see, the stock Syclone and Typhoon heads are at the bottom of the
list when it comes to flow numbers. Putting a lot of money into rebuilding
them and/or porting isn't the best option.
[Tydriver]
I have provided all this information to the best of my ability.. Heres the
following history on what you are going to be looking at.
1996 4.3L V6 VORTEC 772 casting heads
1.94 Intake valve (stock)
1.50 Exhaust valve (stock)
BOTH HEADS were cleaned up and had 3 Angle Valve job done. They were BOTH
flowed on same Flowbench (Superflow600) within minutes of each other.
The one showing PORT work represents my 1st attempt at porting the head,
this was completed at my expense to justify whether porting is needed or
NOT on these heads, and also to verify what direction I was going with the
port work.
The stock head is exactly that.. Nothing more than PORT (gasket) MATCHED.
http://www.nwstp.com/Tydriver/heads/headflow.htm
[/Tydriver]
If you're too lazy to actuall open the link, or for some reason it doesn't
exist, here are the flow numbers:
Intake Stock Vortec Change Exhaust Stock Vortec Change
Lift Lift
0.1 75 75 0 0.1 66 66 0
0.2 135 135 0 0.2 114 111 -3
0.3 193 193 0 0.3 144 145 1
0.4 227 233 6 0.4 153 164 11
0.5 220 225 5 0.5 155 170 15
0.6 217 221 4 0.6 156 172 16
0.7 214 221 7 0.7 156 174 18
Notes: Exhaust side seems to encourage more porting.. I concentrated
on INTAKE SIDE primarily with merely "cleaning" up Exhaust. Notice how
the exhaust side on the STOCK head dies at around .400" of lift. However,
the "ported" head continues to increase, the .700" of lift is really
unusable that is why I went with .500" @ 170CFM as being peak flow (however
the .700 is "most flow" on exhaust) both heads had stock valves installed
and 3 angle valve job on BOTH HEADS before flow test.
[/Tydriver]
[myclone]
The one thing, IMO, to keep in mind is that there are as many ways to do a
build up as there are engines or ppl building them. Something I do all the
time another "engine builder" might feel is completely wrong. Depends on
the person really.
[/myclone]
Heads (Basic)
-------------
A budget rebuild would consist of getting the stock heads freshened at a
machine shop. They should recieve a good cleaning and inspection to make
sure there are no cracks or any problems that would cause them to fail
if they were reused.
It would be wise to install new valve seals since the stock ones are
prone to degrade over the years and lead to the "blue puff of smoke" on
startup. The intake and exhaust valves should be inspected and replaced
if they are not going to be reused, a good three angle valve job wouldn't
hurt a bit either.
The valvesprings should be tested for wear and be within the factory
specifications and if they aren't, they should be replaced. While these
motors aren't high revving, a worn valvespring can lead to valve float
which is never a good thing.
It is recommended that unless you are on a extreme low budget you replace
the valve springs with ones of sufficient seat pressure and rated at
enough lift for future cam and/or rocker ratio changes. Do it while
they are off and you won't have to worry when you decide to change the
cam in the future.
Use a quality aftermarket retainer that is designed for your new valve
springs. Don't bother to skip on these and reuse the stock retainers.
If you are planning on putting a lot of money into the stock heads by
either replacing parts or having them ported, you will probably be better
off going to a set of L35 heads (direct bolt on), that flow better
from the start. If you are dead set on reusing the stock heads, be
certain you or your head porter know what they are doing. For reference,
please see the following post from the SyTY mailing list archives:
http://www.syty.org/archives/syty/0010/msg00199.html
Heads (Intermediate)
--------------------
The 1992 - 1995 L35 heads are a direct replacement for the stock heads on
a Syclone or Typhoon. A post from the SyTy mailing list archives on how
to identify these heads can be found at:
http://www.syty.org/archives/syty/0010/msg01203.html
"I haven't got a collection of casting numbers, but flow numbers have beeen
posted here before. The best way to identify a L-35 head is by the factory
screw in rocker studs. The LB-4 heads have press in studs. You can bolt on
a 92-95 L-35 head. The 96+ heads flow better, but are not a direct bolt on.
The later heads have four bolts on each intake manifold flange, while the
Sy-Ty type have 6. Also the intake ports are moved up about .25''."
There are a number of owners who have upgraded to the L35 heads and are
reporting good results. Since these are a direct bolt on, there is no need
to redrill the intake or the heads to make sure that everything goes back
together properly.
Heads (Advanced)
----------------
The last option for readily available replacement heads are the 1996 and up
Vortec heads. These flow significantly more than the stock heads or the
L35's and have gone 10.71 with no porting on Turbo Tony's Syclone. The major
drawback to using these heads is the bolt hole layout of the lower intake
manifold and the heads themselves.
Stock heads and L35 heads use 6 bolts to hold the lower intake manifold to
the heads while the Vortec heads only use 4. There are two options to make
these heads work on a Syclone or Typhoon. The first is to drill new holes
in the lower intake manifold and weld up the unused bolt holes, the other
is to drill bolt holes in the head so that the lower intake doesn't have
to be modified. Either way, you should know what you're doing or have a
competent machine shop perform the work for you.
If knowledge, ability, or money permit, it is suggested that you use a set
of Vortec heads since they are the best starting point in terms of flow and
design that is readily avaiable to your average Syclone or Typhoon owner. If
this isn't possible, stick with the L35's at a bare minimum. There should
be no good reason to reuse the stock heads other than your budget does not
allow it.
Porting/Port Maching
--------------------
If you have the ability and equipment to port your heads you can do it yourself,
or have it shipped off to a machine shop that knows what they are doing in this
area. There is a difference between just griding away material and correctly
porting your heads. The theory is that you want to get as much flow increase
as possible while removing the least amount of material (?)
Porting/Port Maching (Basic)
----------------------------
A basic porting job would consist of having the runners matched to the ports on
the gasket that you will be using between the lower intake and the heads. Some
work could be done on the combustion chambers to smooth them out which will
avoid any "peaks" that could become hot spots and lead to detonation. Since I
don't know enough about porting heads, any information would be appreciated,
or your machine shop could give you more information.
Basic cylinder head porting will improve the performance of any production
cylinder head by removing flaws that come through mass production. Basic
porting does not attempt to correct any design or engineering deficiencies.
Once your porting project turns to that, you're beyond the scope of basic
porting techniques.
Why is basic port work important to your engine's performance? It reduces
the restriction in the engine's intake and exhaust tracts. Reduce that
restriction and you let more air into the cylinders. If you have more air,
you can add more fuel. The result is increased horsepower.
Most of the work in a basic porting project is focused on reducing those
restrictions which are caused by: 1) "steps" that may obstruct intake air flow
as it transitions from the intake manifold to a smaller intake port entry in
the head; 2) casting bumps, ridges or other marks, such as those you may
find on port floors or roofs; 3) sharp edges, such as those you will find
around the valve guide bosses at the top of the valve pockets; and 4) the
point where the intake port floor curves down to the valve seat.
Porting/Port Maching (Intermediate)
-----------------------------------
The next step would be to do some work to the bowl area and the short side radius
to increase flow into the head. The runners can be enlarged and smoothed out
to promote better flow (while maintaining the correct swirl characteristics),
and the area around the valves cleaned up to unshroud them. A five angle valve
job can be applied.
Porting/Port Maching (Advanced)
-----------------------------------
This step would be to achieve maximum flow through the heads and could entail
welding additional material into the ports to allow more porting without grinding
into the water jackets. The exhaust ports can be enlarged to achieve better
flow (but the headers need to be matched to this as well).
Rocker Arms
-----------
Stock stamped steel rocker arms are sufficient for a stock motor, but
production variances can lead to some rocker arms being more or less than
the designed specification. During a rebuild I would not suggest reusing
the stock rocker arms, but if you plan on doing so, make sure they go back
on the same valve that they came off of to ensure that they have the same
wear characteristics as they did before.
[myclone]
Crane and Comp Cams both make good rockers IMO. I dont care for the Comp
Magnum roller tip rockers(part# 249-1417-16) as they are a PIA to adjust
with the engine running.
Key thing to remember(IMO) is that if you use non self aligning rockers
that are more than 1.52 ratio then open up the push rod slots in the
heads to clear the push rods and use guide plates. Self aligning rockers
dont need guide plates but if you increase the rocker ratio from stock
you will prolly need to open up the pushrod slot in the heads to keep
the push rods from binding at or close to full lift. This would apply
to 1.5 ratio rockers also if you have a ultra high lift cam.
IMO the above is a case by case deal. With manufacturing tolerances and
diff combos the only way to know if you absolutely need to open up the
push rod slots is to check EACH one at max lift with the parts you're
going to use. Ive personally seen some push rod slots be ok as is while
others would rub at max lift on the SAME head so I open them up on all
of them needed or not.
One last thing on rockers. You get what you pay for.. Cheap rockers are
just that. While our engines dont spend time at high RPM nor do they
need huge spring pressures if you can afford the "good stuff" use it.
On the other hand our engines are one of the few I wouldnt have a huge
issue using cheaper "no name" rockers on. We just dont abuse them like
other applications do and its all a matter of how much money you can/want
to spend in this instance.
[/myclone]
Rocker Arms (Basic)
-------------------
Stock replacement rocker arms are available from GM, but it would probably
be wise to go with an aftermarket company that has a higher quality control
process than a mass manufacturer. You can choose from 1.5:1 (stock ratio)
or go up a step to a 1.6:1 rocker arm. With the stock camshaft and ECM,
using a 1.6:1 ratio rocker arm should not cause any ill effects (?)
Rocker Arms (Intermediate)
--------------------------
The next step up in the quality department are roller tipped stamped rocker
arms commonly available from any speed shops (Summit Racing and Jegs come
to mind). The benefit of having a roller tip on the rocker arm is less
friction on the valve tip and better quality control.
Rocker Arms (Advanced)
----------------------
The best rocker arm that can be used on a head is a roller tipped cast body
rocker arm. These are generally more durable and offer the same benefits
of the roller tipped stamped body rocker arms. A number of companies
(Comp Cams, Crane, etc) make these. If you are planning to upgrade your
camshaft, it might be best to get a complete package deal that consists of
all the parts from the same manufacturer.
Valves
------
Stock heads come with 1.94" intake and 1.50" exhaust valves (?). As said
before, Turbo Tony has gone 10.71 with valves this size (mind you it's only
one part of the whole combination), but if you are planning on having the
heads worked on it would probably be beneficial to upgrade your valves to
a set of standard small block chevy 2.02" intake and 1.60" exhaust valves.
[myclone]
660-11566-1 (Manley 2.02" intake w/back cut stem) Using 2.05" might be
better but Ive never tried them(yet)
660-10751-1 (Manley 1.60" exhaust w/back cut stem)
[/myclone]
Valves (Basic)
--------------
In a basic head rebuild you can get away with having the stock size valves
replaced with either factory replacements or a set of aftermarket units.
There are a number of different options you can get when ordering valves
such as swirl polishing, undercut stems, etc.
Valves (Intermediate)
---------------------
John Waller has done some flow testing with a 2.02" intake and 1.60" exhaust
valve and has seen a noticable improvement in flow. The valve seats themselves
will need to be modified so that they can accept the bigger valves and seal
properly when they close. You can order valves with back cut stems,
hardened stems, swirl polished backs and faces, etc. It is best to consult
with your engine builder for the best intake and exhaust valves for your
particular application.
Valves (Advanced)
-----------------
You can get upgraded valves in stainless steel, but if you're going all out
you can get titanium or sodium filled valves to help heat dissipation, etc. It
may be possible to fit 2.05" intake or even a 2.08" intake valve on the heads,
but judging from the flow nubmers listed above, it might be wiser to go with
a bigger exhaust valve instead of a huge intake valve.
Rocker Studs
------------
The stock Syclone and Typhoon heads use press in rocker studs while the later heads
use a set of screw in rocker studs. I'm sure you can convert a set of stock heads
to screw in studs, but it's probably not worth it and the price you would pay to
have this done could probably get you a set of L35 heads at the local junk yard.
[myclone]
Screw in rocker arm studs (requires machine work): 070-234-7201 (ARP 3/8" Pro series)
[/myclone]
Guide Plates
------------
Guide plates can be used on the heads provided certain conditions exist:
1) You have not installed a set of self-aligning rocker arms.
2) The heads have been machined for screw in studs to accept the guideplates and
the holes that the pushrods pass through have been enlarged to avoid any
contact with the pushrod itself
3) You MUST use hardened pushrods.
Coatings (Advanced)
-------------------
There are a number of companies (such as Swain Technologies) that can thermal
coat combustion chambers and valve faces. The coating holds heat inside the
combustion chamber so more usable horsepower can be extracted from it by making
the gaseous products of combustion expand more. The coating also protects the base
metals by insulating them from intense, damaging combustion heat. Parts are protected
from high temperature oxidation, and heat transfer is reduced by spreading the
heat over the entire coated surface, encouraging proper flame travel, and
eliminating hot spots and detonation. Less heat conduction through the coated
parts keeps them cooler and oil temperatures lower.
since my first post about intakes in the tech section didn't get very much input i figured i'd put the one about heads in here. hopefully you guys can help me out (jwaller, you out there?). here's what i have come up with so far, feel free to add information tell me where i'm way off since i pulled most of this stuff outta my ass....
Heads
-----
Since 1991, GM has made several advances in head design that are superior
to the ones used on Syclones and Typhoons. The most popular ones are the
L35 (1992 - 1995?) and Vortec (1996+?) heads. There are other high dollar
aluminum and race designed units, but those are usually out of the price
range of the average owner and some won't work with the stock headers due
to their angle plug design.
When it comes to flow numbers, I found this post from the SyTY mailing list
archives:
http://www.syty.org/archives/syty/0004/msg01215.html
Ok with all the talk of heads and air flow numbers. Idug up some info from
awhile back
Intake at .500 lift at 28" water
LB4 stock SY heads 165 cfm
1995down L35 heads stock 193cfm
1995down L35 heads minor porting 211cfm (at 24" water)
1996 up vortec head possibly 250cfm
1996 up ported vortec head 270cfm
brodix -8head stock 240cfm
brodix -8head ported 285cfm
brodix -10head stock 253cfm
brodix -10head ported 289cfm
As you can see, the stock Syclone and Typhoon heads are at the bottom of the
list when it comes to flow numbers. Putting a lot of money into rebuilding
them and/or porting isn't the best option.
[Tydriver]
I have provided all this information to the best of my ability.. Heres the
following history on what you are going to be looking at.
1996 4.3L V6 VORTEC 772 casting heads
1.94 Intake valve (stock)
1.50 Exhaust valve (stock)
BOTH HEADS were cleaned up and had 3 Angle Valve job done. They were BOTH
flowed on same Flowbench (Superflow600) within minutes of each other.
The one showing PORT work represents my 1st attempt at porting the head,
this was completed at my expense to justify whether porting is needed or
NOT on these heads, and also to verify what direction I was going with the
port work.
The stock head is exactly that.. Nothing more than PORT (gasket) MATCHED.
http://www.nwstp.com/Tydriver/heads/headflow.htm
[/Tydriver]
If you're too lazy to actuall open the link, or for some reason it doesn't
exist, here are the flow numbers:
Intake Stock Vortec Change Exhaust Stock Vortec Change
Lift Lift
0.1 75 75 0 0.1 66 66 0
0.2 135 135 0 0.2 114 111 -3
0.3 193 193 0 0.3 144 145 1
0.4 227 233 6 0.4 153 164 11
0.5 220 225 5 0.5 155 170 15
0.6 217 221 4 0.6 156 172 16
0.7 214 221 7 0.7 156 174 18
Notes: Exhaust side seems to encourage more porting.. I concentrated
on INTAKE SIDE primarily with merely "cleaning" up Exhaust. Notice how
the exhaust side on the STOCK head dies at around .400" of lift. However,
the "ported" head continues to increase, the .700" of lift is really
unusable that is why I went with .500" @ 170CFM as being peak flow (however
the .700 is "most flow" on exhaust) both heads had stock valves installed
and 3 angle valve job on BOTH HEADS before flow test.
[/Tydriver]
[myclone]
The one thing, IMO, to keep in mind is that there are as many ways to do a
build up as there are engines or ppl building them. Something I do all the
time another "engine builder" might feel is completely wrong. Depends on
the person really.
[/myclone]
Heads (Basic)
-------------
A budget rebuild would consist of getting the stock heads freshened at a
machine shop. They should recieve a good cleaning and inspection to make
sure there are no cracks or any problems that would cause them to fail
if they were reused.
It would be wise to install new valve seals since the stock ones are
prone to degrade over the years and lead to the "blue puff of smoke" on
startup. The intake and exhaust valves should be inspected and replaced
if they are not going to be reused, a good three angle valve job wouldn't
hurt a bit either.
The valvesprings should be tested for wear and be within the factory
specifications and if they aren't, they should be replaced. While these
motors aren't high revving, a worn valvespring can lead to valve float
which is never a good thing.
It is recommended that unless you are on a extreme low budget you replace
the valve springs with ones of sufficient seat pressure and rated at
enough lift for future cam and/or rocker ratio changes. Do it while
they are off and you won't have to worry when you decide to change the
cam in the future.
Use a quality aftermarket retainer that is designed for your new valve
springs. Don't bother to skip on these and reuse the stock retainers.
If you are planning on putting a lot of money into the stock heads by
either replacing parts or having them ported, you will probably be better
off going to a set of L35 heads (direct bolt on), that flow better
from the start. If you are dead set on reusing the stock heads, be
certain you or your head porter know what they are doing. For reference,
please see the following post from the SyTY mailing list archives:
http://www.syty.org/archives/syty/0010/msg00199.html
Heads (Intermediate)
--------------------
The 1992 - 1995 L35 heads are a direct replacement for the stock heads on
a Syclone or Typhoon. A post from the SyTy mailing list archives on how
to identify these heads can be found at:
http://www.syty.org/archives/syty/0010/msg01203.html
"I haven't got a collection of casting numbers, but flow numbers have beeen
posted here before. The best way to identify a L-35 head is by the factory
screw in rocker studs. The LB-4 heads have press in studs. You can bolt on
a 92-95 L-35 head. The 96+ heads flow better, but are not a direct bolt on.
The later heads have four bolts on each intake manifold flange, while the
Sy-Ty type have 6. Also the intake ports are moved up about .25''."
There are a number of owners who have upgraded to the L35 heads and are
reporting good results. Since these are a direct bolt on, there is no need
to redrill the intake or the heads to make sure that everything goes back
together properly.
Heads (Advanced)
----------------
The last option for readily available replacement heads are the 1996 and up
Vortec heads. These flow significantly more than the stock heads or the
L35's and have gone 10.71 with no porting on Turbo Tony's Syclone. The major
drawback to using these heads is the bolt hole layout of the lower intake
manifold and the heads themselves.
Stock heads and L35 heads use 6 bolts to hold the lower intake manifold to
the heads while the Vortec heads only use 4. There are two options to make
these heads work on a Syclone or Typhoon. The first is to drill new holes
in the lower intake manifold and weld up the unused bolt holes, the other
is to drill bolt holes in the head so that the lower intake doesn't have
to be modified. Either way, you should know what you're doing or have a
competent machine shop perform the work for you.
If knowledge, ability, or money permit, it is suggested that you use a set
of Vortec heads since they are the best starting point in terms of flow and
design that is readily avaiable to your average Syclone or Typhoon owner. If
this isn't possible, stick with the L35's at a bare minimum. There should
be no good reason to reuse the stock heads other than your budget does not
allow it.
Porting/Port Maching
--------------------
If you have the ability and equipment to port your heads you can do it yourself,
or have it shipped off to a machine shop that knows what they are doing in this
area. There is a difference between just griding away material and correctly
porting your heads. The theory is that you want to get as much flow increase
as possible while removing the least amount of material (?)
Porting/Port Maching (Basic)
----------------------------
A basic porting job would consist of having the runners matched to the ports on
the gasket that you will be using between the lower intake and the heads. Some
work could be done on the combustion chambers to smooth them out which will
avoid any "peaks" that could become hot spots and lead to detonation. Since I
don't know enough about porting heads, any information would be appreciated,
or your machine shop could give you more information.
Basic cylinder head porting will improve the performance of any production
cylinder head by removing flaws that come through mass production. Basic
porting does not attempt to correct any design or engineering deficiencies.
Once your porting project turns to that, you're beyond the scope of basic
porting techniques.
Why is basic port work important to your engine's performance? It reduces
the restriction in the engine's intake and exhaust tracts. Reduce that
restriction and you let more air into the cylinders. If you have more air,
you can add more fuel. The result is increased horsepower.
Most of the work in a basic porting project is focused on reducing those
restrictions which are caused by: 1) "steps" that may obstruct intake air flow
as it transitions from the intake manifold to a smaller intake port entry in
the head; 2) casting bumps, ridges or other marks, such as those you may
find on port floors or roofs; 3) sharp edges, such as those you will find
around the valve guide bosses at the top of the valve pockets; and 4) the
point where the intake port floor curves down to the valve seat.
Porting/Port Maching (Intermediate)
-----------------------------------
The next step would be to do some work to the bowl area and the short side radius
to increase flow into the head. The runners can be enlarged and smoothed out
to promote better flow (while maintaining the correct swirl characteristics),
and the area around the valves cleaned up to unshroud them. A five angle valve
job can be applied.
Porting/Port Maching (Advanced)
-----------------------------------
This step would be to achieve maximum flow through the heads and could entail
welding additional material into the ports to allow more porting without grinding
into the water jackets. The exhaust ports can be enlarged to achieve better
flow (but the headers need to be matched to this as well).
Rocker Arms
-----------
Stock stamped steel rocker arms are sufficient for a stock motor, but
production variances can lead to some rocker arms being more or less than
the designed specification. During a rebuild I would not suggest reusing
the stock rocker arms, but if you plan on doing so, make sure they go back
on the same valve that they came off of to ensure that they have the same
wear characteristics as they did before.
[myclone]
Crane and Comp Cams both make good rockers IMO. I dont care for the Comp
Magnum roller tip rockers(part# 249-1417-16) as they are a PIA to adjust
with the engine running.
Key thing to remember(IMO) is that if you use non self aligning rockers
that are more than 1.52 ratio then open up the push rod slots in the
heads to clear the push rods and use guide plates. Self aligning rockers
dont need guide plates but if you increase the rocker ratio from stock
you will prolly need to open up the pushrod slot in the heads to keep
the push rods from binding at or close to full lift. This would apply
to 1.5 ratio rockers also if you have a ultra high lift cam.
IMO the above is a case by case deal. With manufacturing tolerances and
diff combos the only way to know if you absolutely need to open up the
push rod slots is to check EACH one at max lift with the parts you're
going to use. Ive personally seen some push rod slots be ok as is while
others would rub at max lift on the SAME head so I open them up on all
of them needed or not.
One last thing on rockers. You get what you pay for.. Cheap rockers are
just that. While our engines dont spend time at high RPM nor do they
need huge spring pressures if you can afford the "good stuff" use it.
On the other hand our engines are one of the few I wouldnt have a huge
issue using cheaper "no name" rockers on. We just dont abuse them like
other applications do and its all a matter of how much money you can/want
to spend in this instance.
[/myclone]
Rocker Arms (Basic)
-------------------
Stock replacement rocker arms are available from GM, but it would probably
be wise to go with an aftermarket company that has a higher quality control
process than a mass manufacturer. You can choose from 1.5:1 (stock ratio)
or go up a step to a 1.6:1 rocker arm. With the stock camshaft and ECM,
using a 1.6:1 ratio rocker arm should not cause any ill effects (?)
Rocker Arms (Intermediate)
--------------------------
The next step up in the quality department are roller tipped stamped rocker
arms commonly available from any speed shops (Summit Racing and Jegs come
to mind). The benefit of having a roller tip on the rocker arm is less
friction on the valve tip and better quality control.
Rocker Arms (Advanced)
----------------------
The best rocker arm that can be used on a head is a roller tipped cast body
rocker arm. These are generally more durable and offer the same benefits
of the roller tipped stamped body rocker arms. A number of companies
(Comp Cams, Crane, etc) make these. If you are planning to upgrade your
camshaft, it might be best to get a complete package deal that consists of
all the parts from the same manufacturer.
Valves
------
Stock heads come with 1.94" intake and 1.50" exhaust valves (?). As said
before, Turbo Tony has gone 10.71 with valves this size (mind you it's only
one part of the whole combination), but if you are planning on having the
heads worked on it would probably be beneficial to upgrade your valves to
a set of standard small block chevy 2.02" intake and 1.60" exhaust valves.
[myclone]
660-11566-1 (Manley 2.02" intake w/back cut stem) Using 2.05" might be
better but Ive never tried them(yet)
660-10751-1 (Manley 1.60" exhaust w/back cut stem)
[/myclone]
Valves (Basic)
--------------
In a basic head rebuild you can get away with having the stock size valves
replaced with either factory replacements or a set of aftermarket units.
There are a number of different options you can get when ordering valves
such as swirl polishing, undercut stems, etc.
Valves (Intermediate)
---------------------
John Waller has done some flow testing with a 2.02" intake and 1.60" exhaust
valve and has seen a noticable improvement in flow. The valve seats themselves
will need to be modified so that they can accept the bigger valves and seal
properly when they close. You can order valves with back cut stems,
hardened stems, swirl polished backs and faces, etc. It is best to consult
with your engine builder for the best intake and exhaust valves for your
particular application.
Valves (Advanced)
-----------------
You can get upgraded valves in stainless steel, but if you're going all out
you can get titanium or sodium filled valves to help heat dissipation, etc. It
may be possible to fit 2.05" intake or even a 2.08" intake valve on the heads,
but judging from the flow nubmers listed above, it might be wiser to go with
a bigger exhaust valve instead of a huge intake valve.
Rocker Studs
------------
The stock Syclone and Typhoon heads use press in rocker studs while the later heads
use a set of screw in rocker studs. I'm sure you can convert a set of stock heads
to screw in studs, but it's probably not worth it and the price you would pay to
have this done could probably get you a set of L35 heads at the local junk yard.
[myclone]
Screw in rocker arm studs (requires machine work): 070-234-7201 (ARP 3/8" Pro series)
[/myclone]
Guide Plates
------------
Guide plates can be used on the heads provided certain conditions exist:
1) You have not installed a set of self-aligning rocker arms.
2) The heads have been machined for screw in studs to accept the guideplates and
the holes that the pushrods pass through have been enlarged to avoid any
contact with the pushrod itself
3) You MUST use hardened pushrods.
Coatings (Advanced)
-------------------
There are a number of companies (such as Swain Technologies) that can thermal
coat combustion chambers and valve faces. The coating holds heat inside the
combustion chamber so more usable horsepower can be extracted from it by making
the gaseous products of combustion expand more. The coating also protects the base
metals by insulating them from intense, damaging combustion heat. Parts are protected
from high temperature oxidation, and heat transfer is reduced by spreading the
heat over the entire coated surface, encouraging proper flame travel, and
eliminating hot spots and detonation. Less heat conduction through the coated
parts keeps them cooler and oil temperatures lower.
