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What is a PF35L
large/elongated oil filter and will it fit my car?
What GM
oil filters will fit my 350?
Why does my car smoke
momentarily when I first start it up?
My carbureted car sat
for a year and now dies just after every start?
My fuel
injected car ran out of gas and now won't start even with gas?
What could make my fuel injected car feel sluggish?
What is an adjustable fuel pressure regulator and how does it
work?
What superchargers are available?
What is Mass Air Flow (MAF) vs. Manifold Absolute Pressure
(MAP)?
Should I remove my Mass Air Flow (MAF)
screen?
What happens to the MAF sensor when a supercharger
is installed?
Can a supercharger be installed on a car
with traction control?
What are the benefits/drawbacks of
a freer flowing air filter?
What's the best aftermarket
exhaust for my car?
What aftermarket catalytic converters
are available?
What else can be done to increase air flow
and thus performance?
How does coolant flow through my
engine?
What can I tell by the color of my spark
plugs?
Are there spark plugs available that fit better
with headers?
How can I prevent my header gaskets from
blowing out?
What is the purpose of a water injection
system?
How does a water injection system work?
What is there to gain by using aftermarket rocker arms?
How can I tell if I have a burnt/sticky valve or faulty piston
ring?
What happens to the compression ratio when you
stroke a motor?
What is extrude
honing?
What is a PF35L large/elongated
oil filter and will it fit my car?
This is the same diameter oil filter as the PF25
(standard 350 ci engine) filter, except it is longer. The standard one filters
down to 30 microns, which means any particles 29 microns or smaller will
continue to circulate. The PF35L has synthetic filter element which filters
down to 12 microns which means 11 microns or smaller is the circulating chunk
size. Because the filter is larger, it requires almost an extra 1/2 quart of
oil to be added to crankcase.
This longer filter fits and aligns flush with oil pan
on 305 and 350 cubic inch engines in the the 3rd and 4th generation F-bodies,
so there's little risk of having it bottom out on bumps. But BEWARE if you have
a 1995 model with an oil cooler housing since GM redesigned the '95 cooler
which causes the PF35L to hang slightly below the oil pan thereby taking the
risk that it may hit the ground on bumps and dips. No 1996 or later models got
a cooler so there should be no problem there.
Quote from Hot Rod:
>
> "FILTER TIP"
>
> "Chevy's new V8 heavy-duty "race" oil filter (GM 25013454 or AC PF-35L)
> can replace any PF-25 or PF-35 filter. Its 100-percent synthetic element
> is rated at 12 microns and is so efficient that engine wear is reduced
> by 75-percent in comparison to conventional filters-all without
> restricting oil flow.
>
> (Courtesy Cone Chevrolet.)"
Terry Quinn (tquinn@heartland.bradley.edu) wrote:
> The following information is not specific to the PF35L, but I'm
> hoping that it applies.
> A few years ago, we were working with a filter manufacturer that was
> promoting synthetic (glass fiber) powertrain oil filters. They had
> extensive data on the difference between that type of filter and a
> conventional paper filter.
> While the synthetic filter is rated for smaller particle collection,
> that is not the only significant advantage.
> When filters are rated, they frequently do a so-called "multi-pass"
> test. I don't remember all the particulars, but contaminated oil is
> circulated through the filter, under constant flow, a number of times,
> and the amount of partical removal or collection (cannot remember which
> way it is tested) after a specified number of passes, determines the
> micron rating. All the dirt is not removed in one pass.
> This standard steady state test, with a constant flow, does not tell
> the whole story, however. What this filter company demonstrated was
> that when a filter is subjected to pressure or flow surges (such as
> when starting with cold oil, or even as the flow changes), the filter
> media will flex. Paper media will then tend to release some of the
> contaminants back into the flow stream, in a process termed "desorption."
> The following information is not specific to the PF35L, but I'm hoping
> that it applies.
>
> A few years ago, we were working with a filter manufacturer that was
> promoting synthetic (glass fiber) powertrain oil filters. They had
> extensive data on the difference between that type of filter and
> a conventional paper filter.
>
> While the synthetic filter is rated for smaller particle collection,
> that is not the only significant advantage.
>
> When filters are rated, they frequently do a so-called "multi-pass"
> test. I don't remember all the particulars, but contaminated oil
> is circulated through the filter, under constant flow, a number of
> times, and the amount of partical removal or collection (cannot
> remember which way it is tested) after a specified number of passes,
> determines the micron rating. All the dirt is not removed in one pass.
>
> This standard steady state test, with a constant flow, does not tell
> the whole story, however. What this filter company demonstrated was
> that when a filter is subjected to pressure or flow surges (such as
> when starting with cold oil, or even as the flow changes), the filter
> media will flex. Paper media will then tend to release some of the
> contaminants back into the flow stream, in a process termed
> "desorption." The standard multipass test will not show this to be
> a problem, but the release of the contaminants was very significant,
> and negated much of the advantage of the filtration.
>
> The glass fiber media was much more resistant to desorption than the
> paper media. It also took out more of the contamination in the first
> pass. But was also considerably more expensive. My employer,
> Caterillar, then co-developed a filter with a patented spiral wrap
> strap around the media to prevent flexing and desorption.
>
> So lacking the ability to use a Caterpillar filter (I don't yet have
> one of our 10.2 liter diesels in my 93 T/A :-), I'm using the PF35Ls
> with great confidence that they will make a big difference in engine
> life.
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What GM oil filters
will fit my 350?
Here is a summary of the AC-Delco filters for the 350
F-Body engines:
Filter Anti- Element
Number Length Drainback Type
-------------------------------------------------------------------
PF-25 Short (3-4") No Duragard (20-micron paper)
PF-35 Long (5.5") No Duragard (20-micron paper)
PF-35L Long (5.5") No Ultragard (12-micron synthetic)
PF-1218 Long (5.5") Yes Duragard (20-micron paper)
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Why does my car smoke momentarily when I first start it up?
It depends on what color the smoke is. If it's white,
then you probably have a leaky head gasket which allows coolant to drip into
the combustion chamber while the car is sitting. The next time you start the
car, it's burned off, producing a heavy white steam (almost to the point of
smoke). The head gasket should be replaced, otherwise you run the risk of
blowing it while driving resulting in dumping a good deal of coolant into the
engine followed by overheating if you don't shut the engine.
If it's black smoke then that's excess fuel burning
off. This could be the sign of an overly rich fuel mixture. But it might also
be a leaking fuel injector. While the car sits, gas leaks into the combustion
chamber and the next time you start the car, it all burns off in a black puff
of smoke. A leaking fuel injector should be replaced, although it's not life or
death.
Finally, there is blue smoke. This is oil. It's
probably the valve seals and/or guides which need to be replaced. The
seals/guides leak oil into the combustion chamber while the car sits. Next time
you start it up, the oil burns off resulting in smoke with a definite blue
tint/color. Fixing the problem can be pretty expensive. Although if it's the
valve seals, many mechanics have a tool that blows air into the combustion
chamber via the spark plug hole which allows the valve seals to be removed
without removing the entire head. But it's still expensive. If the car isn't
burning a large amount of oil, then it's probably not worth fixing.
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My carbureted car sat
for a year and now dies just after every start?
Assuming the gas isn't bad and the fuel filter isn't
clogged, it could be a number of things. First check for a hung float or trash
between the needle and seat. The float may also be collapsed which will cause
the needle to stay off the seat and the engine will flood due to too much
fuel.
Also, after sitting for so long, varnish can form on
all the carburetor's internal surfaces and passages. So disassemble it and
clean it up. Pour some "Berrymans B-12" or equivalent in the fuel bowl to
dissolve the years of accumulated varnish and gunk. You can even leave some in
the bowl and fire up the engine. This will clean the passages by forcing it
through. But be warned, Berrymans is very flammable and it will take off paint,
so extreme care should be used.
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My fuel injected car
ran out of gas and now won't start even with gas?
Try priming the fuel rail pressure by turning on the
key (without engaging the starter). The fuel pump should run 2-3 seconds (a low
hum/buzz) and then shut off. Turn the key off for 10-15 seconds. Repeat this
2-step sequence several times. There may be a flood condition - if so press the
accelerator pedal to the floor and the ECM will go into a "clear flood" mode.
Then try cranking the engine.
If you didn't hear the hum/buzz of the fuel pump as
mentioned above, then you've it's possible that you've blown a fuse or burned
out the fuel pump motor. Check the owner's manual for the proper fuel pump fuse
location. The worst possible case is a burned out pump.
Otherwise, the fuel pump could have sucked in some
sludge from the fuel tank as it was starving for fuel, in which case you could
have a blockage somewhere in the fuel line. Hopefully, it's only in the fuel
filter which you can replace yourself. Otherwise, the entire fuel line probably
needs a professional cleaning.
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What could make my
fuel injected car feel sluggish?
Assuming you've tried a fuel injector cleaner which
is added to the gas tank, you might want to try having the injectors
professionally cleaned. This involves disconnecting the fuel pump and hooking
up a can of injector cleaner to fuel rail. Then you run the engine which uses
the cleaner to clean out the injectors. It could also be the knock sensor which
is installed into the block and can be over
torqued. When this condition
exists, it makes the sensor very sensitive to engine noise which can cause the
timing to retard when there is no detonation which reduces power. You can check
the torque of the sensor or even add some compound or teflon tape to reduce the
sensitivity.
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What is an adjustable
fuel pressure regulator and how does it work?
Fuel injected engines have a regulator just before
gas flows into the injectors. The regulators ensure that consistent pressure is
maintained (through better atomization of the fuel spray) as gas flows into the
injectors. The pressure is measured in pounds per square inch
(psi). A number
of companies (like TPIS) sell adjustable regulators that allow you to vary
(increase or decrease) the pressure/flow of the gas there by modifying
performance. There's an adjustable screw on the regulator used to
set the pressure. There are usually no marks on the regulator showing you the
exact pressure setting, so it's really hit or miss when you're adjust it. There
are a number of fuel pressure gauges (like that from
NOS) which can give you a
more accurate measurement. This is probably the best way to go.
Before you start setting the pressure, remember to
have the key in the "ON" position, but do not have the engine running. Once you
have your base down (say like 49 psi) approximately 1/4 of a turn will give you
a 3 to 4 psi increase. But it's much easier with a gauge if you can get
one.
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What superchargers are
available?
Both Vortech and Paxton
(Granatelli) have
superchargers available. Both have claims which are upwards of 385 HP and 400
lb-ft of torque on the 4th generation LT1s. This would also require
intake/exhaust flow modifications as well. The blowers require no major
mechanical mods but must use a big pulley to keep boost low since the LT1 is
running 10.5:1 compression ratio. Both systems cost between $3000 and $4000
depending on dealer and installation charges can run you upwards an additional
$600. One of the main differences between the two, is the Vortech gears are
lubricated by the engine oil and the Paxton has it's own lubrication system.
People running them are extremely happy with them. Although complaints of leaky
rear main seals and head gaskets are not uncommon. Plus Paxton's technical
support has not been given many high scores. ATI Prochargers should have some
on the market very soon as well (9 psi, 12 psi, and 17psi). So will Powerdyne
which uses a patented kevlar toothed belt internally with aerospace quality
ceramic/metalic bearings so that no oil lubrication is required. They're also
working on an intercooler option. They say that it's not as necessary with
their blower because the outlet temps aren't nearly as high, but it still helps
to boost the HP levels with a lower inlet temp. 6 psi and 9 psi boost levels
are slated. Something to watch out for is the 1994 and later cars
which have traction control (ASR). That's because the TC unit is right where
the supercharger pump gets located. You will ultimately have to move this part
of the brake system to where the old stock air filter box went (behind the
driver side headlight). This means openning and extending the brake lines.
Back To Top
What is Mass Air Flow
(MAF) vs. Manifold Absolute Pressure (MAP)?
The Mass Aif Flow
(MAF) sensor is device that detects
the flow of air going into the engine. In the sensor there is a wire called a
hot wire anemometer that the computer puts power through. As the air passes
over the wire, it makes a cooling effect, and the computer will alter the
resistance of wire. This reading, along with other sensor readings, is then
used to determine and set the correct air/fuel ratio, fuel flow, and timing for
the engine. This method of airflow measurement allows the car's computer to
more easily adapt to modifications like freer flowing intake and exhaust
systems. The downside is the MAF's screen and wires impeed airflow slightly.
But read further on for possible modifications.
The Manifold Absolute Pressure (MAP) sensor is a
device which monitors manifold vacuum. It's sometimes referred to as speed
density. It is connected to a vacuum nipple on the throttle body and
electrically to the engine controller. The sensor transmits information on
manifold vacuum conditions and barometric pressure to the car's computer. Based
on lookup tables, the MAP sensor data along with data from other sensors is
used to determine the correct air/fuel ratio, fuel flow, and timing based on
RPMs and throttle position. Changes in throttle can be reacted on more quickly
than with MAF since the lookup tables work much quicker as there's no loop to
look for a MAF reading and followed by a calibration. Also, there's no
hinderance to airflow MAP since it's a sensor working inside the intake
manifold However, this method is less adaptable to engine modifications since
the lookup tables are meant for the stock air flow setup and they can't be
changed without reprogramming the computer or chaning the chip.
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Should I remove my
Mass Air Flow (MAF) screen?
Alot of times you will hear about people removing
their MAF screens. These are a number of wires (as described above) in a cross
section through the air intake. On the 3rd generation cars, removing these MAF
screens can increase air flow by upwards of 200 cfm (~40%) yielding better
performance (throttle repsonse). The problem is that the MAF allows you to make
modifications to the engine where the ECM will be able to calibrate itself
better than a MAP system can. Without the screens, the computer may not adjust
itself for as it could with the screens. Although no 3rd gen owners (with or
without modifications) have really had problems removing the screens, it seems
that there isn't much advantage to doing this on the 4th gens because the
screens aren't that inhibiting. Some 4th gen dyno results have shown no gains
by removing the screen. It's also important to note that the '93 LT1s use MAP
(no screen), where as the '94s and up use MAF.
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What happens to the
MAF sensor when a supercharger is installed?
The MAF is barely visible as it's mounted down
between the air filter and the supercharger intake. Also, the Paxton includes
Paxta-Map unit contains three injectors in a mount and a remote programmer that
lets you turn them on/off individually or in series as the boost
increases/decreases. Its purpose is to keep the car from leaning out under
heavy boost, which causes detonation. Originally, it was a $500 option, but now
they include it as part of the supercharger kit.
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Can a supercharger be
installed on a car with traction control?
Yes, however, the installation is hairy. You have to
move the traction control unit (which is located right where the supercharger
goes) to another location behind the driver's side headlight area. Then you
have to splice, extend, and re-route the brake lines to do it. If you plan to
do this, it's highly recommended that you go someplace that is "fabrication"
savvy and not just simply mechanics savvy. There is a distinction. Also figure
on an additional 6 to 8 hours of labor to do this.
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What are the
benefits/drawbacks of a freer flowing air filter?
Free flowing air filters such as K&N can provide
a minimal increase in power (maybe 5 HP). The materials they're made of allow
air to flow through much more freely than through stock paper air filters. The
drawback to this is that more dirt can also pass through the air filter since
the pores are usually bigger to allow for freer air flow. Some people have
claims that the filters are great, while others think they only foul up
performance due to the dirt they allow in. The jury seems to be hung on this
issue.
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What's the best
aftermarket exhaust for my car?
It all boils down to personal preference. While each
manufacturer claims to be better than all the others, there really isn't one
which stands out over all the rest. In a recent mailing list poll, a number of
3rd and 4th generation owners responded with their experiences.
Flowmaster, Borla, Street Legal Performance, and Dynomax seem to be the popular choices
with Flowmaster and Borla having a slight advantage in popularity, but not by
much. A good review was also given to Gale Banks. Flowmaster owners seemed to
only make replacements to the muffler, while most others did a whole cat-back
replacement. While there are no hard facts of improvements by replacing the
whole exhaust system (cat-back), it seems to be the more popular choice.
Flowmaster people don't think there's a difference, but the others think there
might be in increasing the pipe diameters by 1/4 to 1/2 an inch. No matter
which, a performance gain will be had by all.
As for noise levels, Flowmaster and SLP seemed to be
somewhat noisier than stock and other systems. There was even mention of a
droaning "hum" from Flowmaster at cruising speed. Whether this is plus or minus
is, once again, a personal preference issue. Borla can also be loud if the
baffle is open allowing exhaust to bypass the muffler. Dynomax seems to win the
"mellow" award as there were no complaints of it being too loud at idle or
cruise speeds. Of course all of the systems produce a roar at wide open
throttle which can be heard from blocks away.
There weren't any real complaints about systems (as
expected). The common praises include: Borla = adjustable bypass baffle is the
biggest advantage providing adjustable performance and volume levels.
Flowmaster = makes a performance car sound like it should - "mean". SLP = deep
and throaty, 'nuff said. And Dynomax = sweet and mellow to the ears, yet
getting on the throttle will remind you why it's there.
Finally, there's price. Borla is probably the most
expensive at $600 and above. But it's also the only system with an open exhaust
baffle to bypass the muffler and it's stainless steel (guaranteed for life).
Whether the performance gain is that much higher over the others without the
baffle, is still unknown. SLPs can be found for just under $400, Dynomax about
$200, and Gale Banks about $300. Flowmasters can be found for under $100
because it's the muffler only.
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What aftermarket
catalytic converters are available?
The cats on the 4th gen F-Bodies are probably the
least restrictive of any production car. Not much can be gained by replacing
it. Removing it or hollowing it out on the other hand can do wonders. But don't
forget that's also illegal (at least for the street). For spend-thrifts, Random
Technologies makes a free-flow cat for just about every F-Body.
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What else can be done
to increase air flow and thus performance?
You can put on a larger throttle body size along with
the addition of an air foil to smooth the flow of the air. 1 5/8" headers will
probably provide one of the largest increases in power. Then there's also CNC
(computer numerical control) porting of the heads which can be done, although
that can get quite expensive, it's quite "THE" air-flow tweak.
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How does coolant flow
through my engine?
In an original generation I type smallblock engine,
coolant enters the front of the block and circulates through the block's water
jacket. The coolant is heated by the cylinder cases, and then this hot coolant
is then routed through the cylinder heads and intake manifold before returning
through the thermostat to the radiator. Since the thermostat is on the exit
side of the system, it does not have direct control over the cold water
entering from the radiator, which enters the block all at once when the
thermostat opens and causes an extreme thermal shock. Besides the shock to the
system, this standard cooling technique sends coolant already heated by the
block to the heads, thus promoting detonation.
The LT1 is completely different since it uses reverse
flow cooling. The incoming coolant first encounters the thermostat, which is
now on the inlet side of the system. Depending on the engine coolant
temperature, cold coolant from the radiator is allowed to enter the engine.
This allows a more controlled amount of cold coolant to enter, which mixes with
the bypass coolant already flowing. This virtually eliminates the thermal shock
present in the old system, since in essence the cold coolant is metered
carefully in as necessary. After entering through one side of the 2-way
thermostat (at the appropriate temperature), the cold coolant is routed
directly to the cylinder heads first, where the combustion chambers, spark
plugs and exhaust ports are cooled. Then the now heated coolant returns to the
engine block and circulates around the cylinder barrels. The hot coolant from
the block now reenters the water pump, and hits the other side of the 2-way
thermostat, where it is either recirculated through the engine or directed to
the radiator, depending on temperature. The main concept behind reverse flow cooling is to
cool the heads first, which greatly reduces the tendandy for detonation, and is
the primary reason that the LT1 can run 10.5 to 1 compression and significant
ignition advance on today's gas. This is the key to the LT1s increased power
over the generation I smallblock. Both sides of the LT1 2-way thermostat are directly
linked together, and there is only 1 wax pellet that controls the spring
mechanism. Both the stock and Hypertech 160 degree units are "2-way"
thermostats in that they regulate coolant flow both out of and into the engine,
while the bypass portion of the thermostat supplies the water pump with a full
flow of coolant at all times. This is very much unlike the generation I
smallblock engine thermostat.
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Are there spark
plugs available that fit better with headers?
Accel makes shorty U-groove plugs which are easily
installed and removed with aftermarket headers.
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What can I tell by
the color of my spark plugs?
Normally they will be black on the outer edge. But,
the center electrode can be a number of colors:
-
White - running lean (or it's a new plug)
-
Light Gray - running good
-
Light Reddish Gray - running good on gas with
octane boosts
-
Dull Black (soot) - running rich
-
Shiny Black (oil) - bad rings and/or valve guides
-
Gas (will smell) - no spark
You have to drive the car to operating temperature
before taking the plugs out. If you start it cold, drive it a minute, and shut
it off the plugs may be black from the cold start enrichment (engine runs a
little rich until warmed up).
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How can I prevent my
header gaskets from blowing out?
Try replacing the header bolts with Stage-8 header
bolts and also try using the LockTite compound for aluminum on your bolts.
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What is the purpose
of a water injection system?
It is designed to let you safely run higher boost on
a high compression engine (like that which is supercharged). It probably won't
do anything for a stock engine, unless you bump compression so high that it
detonates. The water cools the intake by 60-100 degrees F depending on the
ambient temp and altitude. The hotter it is outside, the more it cools. It does
this through the heat of vaporization of the water. The water also raises the
apparent octane of the fuel by 10%, meaning it makes 93 octane run like 102.
This is because the cooler charge burns slower and resists
pre-ignition. Another
benefit is buffering of the combustion process and smoothing of the power
strokes (that is, a tremendous increase in detonation resistance). All this
allows you to run full timing advance and make more power.
The overall result is the same effect as an
intercooler, but you don't have to increase the boost on the supercharger to
make up for intercooler losses. That means less supercharger drag. Drawbacks
are more maintenance. Once dialed in, it's transparent, but you do have to
refill the water reservoir every so often, to ensure you don't run out under
high boost. Also, the ignition system must be in top form. A weak ignition
could experience misfire problems resulting in too much water being injected
which will kill the combustion process and be harder on the rings and exhaust
valves.
A good system that is properly calibrated can yield
impressive results. It must be able to monitor both engine speed and boost
level to determine how much water and when to inject.
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How does a water
injection system work?
The system is powered by a 100-psi high-volume water
pump that is triggered by a pressure switch attached to the intake manifold. It
can be set to activate from just over 0-psi to over 10 psi (3 psi is a good
point). Once activated, the system pulls water from the windshield washer tank
using an adapter supplied in the kit and injects it through a stainless nozzle
which is usually installed in the intake (supercharger) elbow (about 6 inches
before the throttle body). Higher end systems have their own water tank, some
of which are pressurized. The nozzle is a precision device which meters the
water in gallons per hour. It resembles a 1/2 inch ball bearing cut in half
with a hole in it. A 12 or gal/hr nozzle should be sufficient for most
applications, but a 15 gal/hr is good for higher boost levels. The water comes
out under very high pressure as a fine mist in a conical shape, and is
immediately pushed into the engine by the output of the supercharger.
In the tank is a mixture of distilled water and
isopropyl alcohol. A water to alcohol ratio of 7:1 is good for the street and
3:1 for racing. The amount used by the system is very dependant on how often
you activate it. It's very cheap so it shouldn't be a concern, as one gallon
should last a long time.
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What is there to gain
by using aftermarket rocker arms?
The small-block Chevy engine used stamped-steel
rocker arms since its inception. They are light, strong, reliable, and
adjustable. If you aren't modifying your engine with a high lift camshaft there
is no need to replace the stock rockers. The stock rocker arm ratio is 1.50:1, meaning that
the rocker arm multiplies the cam lobe lift by a 1.50 factor. Thus a cam with a
0.300 cam lobe lift has a valve lift of 0.450 inches. A 1.60:1 rocker will
provide 0.480 inches of lift at the valve on the same cam. Going from a 1.50 to
1.60 rocker ratio though will reduce the RPM at which the valves float. To
maintain the same valve float speed, you must increase the valve spring
pressure by 10%. Still, switching over to 1.60 ratio rocker arms is a good and
relatively inexpensive way to get some more power (10 - 15hp) from your engine.
Going beyond a 1.60 ratio can be expensive and will most likely require
different pushrods in order to maintain correct geometry. Replacing the stock
rocker arms with aftermarket 1.50 rockers will make a difference simply because
they have tighter than stock tolerances in the manufacture of the parts.
Typically, the stock 1.50 rockers will have less than the specified ratio,
which means less valve lift with some valves getting .450, a few getting .420,
and a few others getting .400. The difference alone could cause a loss of
power. Be aware also, that you may have to enlarge the
pushrod guide slots that are cast in the cylinder head with larger than 1.50
ratio rockers. The pushrod may hit the end of the slot because the pushrod seat
on the rocker arm is moved closer to the stud in order to obtain the larger
ratio. Naturally you will have to take the heads off to do so.
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How can I tell if I
have a burnt/sticky valve or faulty piston ring?
If a cylinder's compression is low, that's usually
indicative of either a burnt/sticky valve or a faulty piston ring. To determine
which it is, take a compression reading on the suspected cylinder, and then
squirt in some oil down into the piston through that cylinder's spark plug
hole. Then take another compression reading. If the pressure is the same,
you've got a burnt/sticking valve. If it improves drastically (like 100 PSI or
more), you've got a faulty piston ring.
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What happens to the
compression ratio when you stroke a motor?
Stroking usually involves increasing the cubic
inches. The compression ratio will go up. Compression ratio is the ratio of the
cylinder and head volume with the piston at Top Dead Center
(TDC) to the total
volume at Bottom Dead Center (BDC). Since the piston is moving down further at
BDC, but returning to the same position at TDC, the swept cylinder volume
increases while the volume at TDC remains the same. Hence, the compression
ratio increases.
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What is extrude
honing?
Extrude Hone is a subdivision of PowerFlow Corp. It
is actually slang now for the process that they perform on intakes,
impellers (jet skis), heads, and exhaust manifolds. The process involves taking a
metallic putty (like abrasive toothpaste) which is
pressurized inside of the
part to be "honed". The putty is moved/flowed back and forth by hydraulic
pistons that are connected to the ports of the fixture/jig that is attached to
your part. This abrasive scrubbing machines off a part of the finish, leaving
it almost perfectly smooth. The process is also used to balance the flow in
intakes, head ports, and exhaust ports since it is extremely accurate.
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