RE: [Chrysler300] Thermodynamics of a Ram

[christopher beilby <thelastbestgenius@xxxxxxxxxxx>]

Rather than pull the heads, if you remove one rocker cover, and on one cylinder can back off the pushrods a little, and crank the motor doing a comp test on that cylinder, you then might get a higher reading that gives an idea if stock piston fitted?!
May take two or three goes, to guess just how many turns to back pushrod adjustment off - that if the motor you trying it on has adjustable pushrods.
 
My modified 1967 AC Cobra had such a wild (Ford issue for racing) cam that it dropped cranking comp from over 200 to 160lbs, so until you get rid off cam overlap, you will have no idea of piston comp ratio.
 
Maybe easier than pulling heads?!
 
Christopher in Australia - our long crazy southern winter finally over, though nothing like the real bad weather some of you on east coast have seen - glad to hear most all OK, even if gas some places there rarer than free beer ?!
 

> To: kboonstra@xxxxxxxxxxxx; mmoore8425@xxxxxxx
> CC: schroe99@xxxxxxxxxxxx; rixpac@xxxxxxx; larry@xxxxxxxxxx; tfm@xxxxxxxxxxxx; c300@xxxxxxx; mgoodknight@xxxxxxxx; chrysler300@xxxxxxxxxxxxxxx
> From: flatheadeng@xxxxxxxxxxx
> Date: Sat, 10 Nov 2012 12:25:34 -0700
> Subject: Re: [Chrysler300] Thermodynamics of a Ram
> 
> As they say close counts in horseshoes and hand granades. You method will be 
> "close". It assumes same gasket crush no head surfacing and same valve 
> pockets. If you really want to know pull a head and look at the pistons.
> ----- Original Message ----- 
> From: "Keith Boonstra" <kboonstra@xxxxxxxxxxxx>
> To: "Michael Moore" <mmoore8425@xxxxxxx>
> Cc: "Carlton Schroeder" <schroe99@xxxxxxxxxxxx>; "'RICK AND DEBBIE CLAPHAM'" 
> <rixpac@xxxxxxx>; <larry@xxxxxxxxxx>; <tfm@xxxxxxxxxxxx>; 
> <flatheadeng@xxxxxxxxxxx>; "'Rich Barber'" <c300@xxxxxxx>; 
> <mgoodknight@xxxxxxxx>; <chrysler300@xxxxxxxxxxxxxxx>
> Sent: Saturday, November 10, 2012 12:03 PM
> Subject: Re: [Chrysler300] Thermodynamics of a Ram
> 
> 
> > Hi Mike,
> >
> > The folks writing here are far more erudite and experienced than I on this 
> > whole subject area, so I wonder if I'm missing something to think the 
> > direct answer to your question is a little less complicated. If your 
> > rebuilder changed the pistons in order to lower the compression, the tops 
> > of those new pistons must necessarily ride lower in the cylinder.
> >
> > I wonder if you could simply measure the distance from the top of a spark 
> > plug hole down to the top of the piston at TDC and BDC. You can then ask 
> > for one of us to do the same on a known-to-be-stock H engine. If your 
> > measurements are greater, your pistons must have been changed. If the 
> > measurements match, your compression should too.
> >
> > N'est-ce pa?
> >
> > Keith Boonstra
> >
> > -
> > On 11/10/2012 10:14 AM, Michael Moore wrote:
> >>
> >> Thanks Carl,
> >> As a matter of interest, the reason I asked the question initially was to 
> >> get an idea as to whether my rebuilder 20 years ago, concerned about 
> >> emissions control and loss of premium gasoline, as he prepared my 300H 
> >> for a move to California, had installed low compression pistons.
> >>
> >> He had made other mods supporting that goal. I was just looking for a 
> >> general idea of what compression readings stock (driver) 300H's ought to 
> >> be so I could compare mine and make a judgement about pistons.
> >> Thanks again, Mike
> >>
> >> On Nov 10, 2012, at 6:54 AM, Carlton Schroeder wrote:
> >>
> >> Hello,
> >> This subject appears to be another example of a question being more
> >> complicated than it might first seem. Just on the matter of an engines
> >> compression ratio I thought (and still do) it is just a volume ratio of 
> >> the
> >> sum of the cylinder volume the piston moves through + the combustion 
> >> chamber
> >> volume divided by the combustion chamber volume. With odd shaped 
> >> combustion
> >> chambers, valve tops, the spark plug, head gaskets, and non-flat piston 
> >> tops
> >> the exact volume calculations would be complicated. I guess though if you
> >> really wanted to determine a precise CR you could use oil and fill the
> >> volumes (piston at the bottom and piston at the top) and determine the CR
> >> from that data. The valves would have to be closed and to be really 
> >> precise
> >> you would have to account for that little additional volume in the spark
> >> plug core.
> >> For another method if the piston was at the bottom and you could make a
> >> pressure and temperature reading then and could also measure the pressure
> >> and temperature in the combustion chamber at the end of the compression
> >> stroke then from gas laws you should be able to calculate the CR.
> >> I hope this understanding is consistent with the rest of the posts I've 
> >> been
> >> reading.
> >> Carlton Schroeder
> >> Eagle River, WI
> >>
> >> -----Original Message-----
> >> From: Chrysler300@xxxxxxxxxxxxxxx <mailto:Chrysler300%40yahoogroups.com> 
> >> [mailto:Chrysler300@xxxxxxxxxxxxxxx 
> >> <mailto:Chrysler300%40yahoogroups.com>] On
> >> Behalf Of RICK AND DEBBIE CLAPHAM
> >> Sent: Saturday, November 10, 2012 7:33 AM
> >> To: larry@xxxxxxxxxx <mailto:larry%40pwbsfo.com>; tfm@xxxxxxxxxxxx 
> >> <mailto:tfm%40zippynet.com>; mmoore8425@xxxxxxx 
> >> <mailto:mmoore8425%40aol.com>;
> >> flatheadeng@xxxxxxxxxxx <mailto:flatheadeng%40comcast.net>; Rich Barber; 
> >> mgoodknight@xxxxxxxx <mailto:mgoodknight%40juno.com>
> >> Cc: chrysler300@xxxxxxxxxxxxxxx <mailto:chrysler300%40yahoogroups.com>
> >> Subject: RE: [Chrysler300] Thermodynamics of a Ram
> >>
> >> Larry, I have been where you are at many times self-inflicted and with
> >> customer's choice. A camshaft change will cure the problem. Actually
> >> Hemispherical combustion chambers can withstand higher dynamic 
> >> compression
> >> ratios. The chart / tool you have posted will help. I also know finding a
> >> 392 cam is now difficult. Rick
> >>
> >> To: rixpac@xxxxxxx <mailto:rixpac%40msn.com>; tfm@xxxxxxxxxxxx 
> >> <mailto:tfm%40zippynet.com>; mmoore8425@xxxxxxx 
> >> <mailto:mmoore8425%40aol.com>;
> >> flatheadeng@xxxxxxxxxxx <mailto:flatheadeng%40comcast.net>; c300@xxxxxxx 
> >> <mailto:c300%40ez2.net>; mgoodknight@xxxxxxxx 
> >> <mailto:mgoodknight%40juno.com>
> >> CC: chrysler300@xxxxxxxxxxxxxxx <mailto:chrysler300%40yahoogroups.com>
> >> From: larry@xxxxxxxxxx <mailto:larry%40pwbsfo.com>
> >> Date: Fri, 9 Nov 2012 21:55:26 -0600
> >> Subject: RE: [Chrysler300] Thermodynamics of a Ram
> >>
> >> Sorry This has nothing to do about the ram effect but I thought I would
> >> chime in anyway
> >>
> >> The way I understand it is that the 10 to 1 compression is the static
> >> compression ratio which is what you would get when the piston travels 
> >> from
> >> the bottom of the stroke to the top of the stroke with the valves being
> >> closed at all times
> >>
> >> And to get the real compression ratio or dynamic compression ratio all 
> >> the
> >> figures as far as stroke, bore, head gasket thickness ect. Would be the 
> >> same
> >> for both Accept putting in the degrees ABDC that you have the intake 
> >> valve
> >> close
> >>
> >> Below is a link that will give you both ratios if you have all the 
> >> numbers
> >> to put in
> >>
> >> http://kb-silvolite.com/calc.php?action=comp
> >>
> >> 300D 392
> >>
> >> I used this when I had my engine rebuilt & had the cam designed so we 
> >> would
> >> come up with a cam that should be good for the crappy gas we have out 
> >> here
> >> in CA especially in the Bay Area
> >>
> >> I ended up with a static of 9.1 & a dynamic of 7.6 which supposedly it
> >> perfect for 91 octane
> >>
> >> I think this works for most engines except hemis from the fifties
> >>
> >> After doing all this it still pings under load even by controlling the 
> >> total
> >> spark advance to 24 degrees
> >>
> >> The only thing that makes it happy is 96 octane at the race track which
> >> costs about $7.00 a gallon
> >>
> >> If anyone has had this issue of pinging with a 392 and has any solutions 
> >> I
> >> would like to hear about it
> >>
> >> Thank you
> >>
> >> Larry Jabin
> >>
> >> -----Original Message-----
> >> From: Chrysler300@xxxxxxxxxxxxxxx <mailto:Chrysler300%40yahoogroups.com> 
> >> [mailto:Chrysler300@xxxxxxxxxxxxxxx 
> >> <mailto:Chrysler300%40yahoogroups.com>] On
> >> Behalf Of RICK AND DEBBIE CLAPHAM
> >> Sent: Friday, November 09, 2012 7:05 PM
> >> To: tfm@xxxxxxxxxxxx <mailto:tfm%40zippynet.com>; mmoore8425@xxxxxxx 
> >> <mailto:mmoore8425%40aol.com>; flatheadeng@xxxxxxxxxxx 
> >> <mailto:flatheadeng%40comcast.net>; Rich
> >> Barber; mgoodknight@xxxxxxxx <mailto:mgoodknight%40juno.com>
> >> Cc: chrysler300@xxxxxxxxxxxxxxx <mailto:chrysler300%40yahoogroups.com>
> >> Subject: RE: [Chrysler300] Thermodynamics of a Ram
> >>
> >> These explanations are quite adequate on the RAM EFFECT. The camshaft 
> >> design
> >> explanation still has me confused. The short ram is basically a 361 
> >> camshaft
> >> with 4 degree retard. I read my fathers papers on cam design and realize
> >> Chrysler had the best labs of any manufactures of the auto industry. They
> >> did know what the wanted and they built it. The bad news is the 
> >> compression
> >> has not been effectively used until direct injection. I know we think we
> >> have 10 to 1 compression ratio engines we just do not. The valves open 
> >> and
> >> close at specific timing and if you figure it out we really never use the
> >> rated compression ratio, Less than half the rated. Here in Colorado we 
> >> can
> >> drive to the top of Pikes Peak on regular gasoline. Being your effective
> >> compression ratio is effected by altitude. at 5000 foot above sea level 
> >> you
> >> lost 20% of the sea level atmosphere. Actually lowering the efective
> >> compression ratio.
> >>
> >> CC: Chrysler300@xxxxxxxxxxxxxxx <mailto:Chrysler300%40yahoogroups.com>
> >> To: mmoore8425@xxxxxxx <mailto:mmoore8425%40aol.com>; 
> >> flatheadeng@xxxxxxxxxxx <mailto:flatheadeng%40comcast.net>; c300@xxxxxxx 
> >> <mailto:c300%40ez2.net>;
> >> mgoodknight@xxxxxxxx <mailto:mgoodknight%40juno.com>
> >> From: tfm@xxxxxxxxxxxx <mailto:tfm%40zippynet.com>
> >> Date: Fri, 9 Nov 2012 20:20:05 -0500
> >> Subject: Re: [Chrysler300] Thermodynamics of a Ram
> >>
> >> Here's a link to our web site where you'll find the operational theory
> >> behind cross ram induction. Cam timing is *critical* to getting the most
> >> optimal performance from this setup.....
> >>
> >> http://www.chrysler300club.com/uniq/allaboutrams/ramtheory.htm
> >>
> >> TFM
> >>
> >> Thomas F. Miller
> >> tfm@xxxxxxxxxxxx <mailto:tfm%40zippynet.com>
> >>
> >> '57 300C
> >> '70 440+6 'Cuda
> >>
> >> >>> "Flathead Engineering" <flatheadeng@xxxxxxxxxxx
> >> <mailto:flatheadeng%40comcast.net>> 11/9/2012 6:33 PM
> >> >>>>>>
> >>
> >> My understanding of the ram effect based on fluid dynamics is the when a
> >> traveling wave of pressure meets a boundry condition, closed valve, the
> >> velocity goes to zero and the pressure doubles. The velocity of the
> >> traveling wave and the frequency depend on the geometry of the passage 
> >> and
> >> the RPM of the engine. The Chrysler ram is long thus tuned to a lower
> >> frequency to complement the large displacement of the engine which turns 
> >> a
> >> relatively low RPM compared with a race engine. Understanding this you 
> >> can
> >> see why the wrong camshaft will destroy the ram effect and make for a 
> >> poor
> >> performing engine. I imagine Chrysler spent a large sum to optimise the 
> >> cam
> >> profile and I doubt if some race engine builder can improve on it. More 
> >> than
> >> likely they will not understand the principles and put in an 
> >> inappropriate
> >> cam that works great on a dual plane manifold but is totaly wrong for the
> >> ram effect.
> >> ----- Original Message -----
> >> From: Rich Barber
> >> To: 'Michael Moore' ; mgoodknight@xxxxxxxx 
> >> <mailto:mgoodknight%40juno.com>
> >> Cc: Chrysler300@xxxxxxxxxxxxxxx <mailto:Chrysler300%40yahoogroups.com>
> >> Sent: Friday, November 09, 2012 3:15 PM
> >> Subject: [Chrysler300] Thermodynamics of a Ram
> >>
> >> Warning: There will be a quiz at the end of this mini-lecture. If you're 
> >> not
> >> interested in engine performance and the ram induction effect, tune out 
> >> now.
> >>
> >> If the cam allowed some valve opening before TDC on the compression 
> >> stroke,
> >> the effective compression could be lower. That would be a real power 
> >> robber,
> >> methinks.
> >>
> >> Simply speaking, a 4-stroke cycle engine acts as an air compressor while
> >> being spun by the starter. The compression pressure is measured as the 
> >> peak
> >> pressure in the cylinder over a small number of strokes-as PSIG (Pounds 
> >> per
> >> square inch-gauge). The Shrader valve in the peak pressure indicator acts 
> >> as
> >> a check valve to hold the peak pressure on the gauge until released.
> >> Ideally, the peak pressure can be estimated by the cylinder's compression
> >> ratio. The laws of physics mandate use of absolute units when dealing 
> >> with
> >> the gas laws, therefore we must use pressures expressed in PSIA (pounds 
> >> per
> >> square inch-absolute). PSIA=PSIG plus atmospheric pressure. Differential
> >> pressures are expressed as PSI.
> >>
> >> Examples:
> >>
> >> Sea Level Atmospheric Peak Peak
> >>
> >> Elevation Pressure Compression Pressure Pressure
> >>
> >> Feet PSIA Ratio :1 PSIA
> >> PSIG Engine & Location
> >>
> >> 16 14.69 9.6 141.02
> >> 126 (My ram K engine at Newark, CA)
> >>
> >> 16 14.69 8.5 124.87
> >> 110 (My C-300 hemi at Newark, CA)
> >>
> >> 5,280 11.68 9.6 112.13
> >> 100 (My ram K engine on the first step of State Capitol Building in
> >> Denver)
> >>
> >> 16 17.69 9.6 169.82
> >> 155 (My ram K engine at Newark with a 3 psi boost from ram induction)
> >>
> >> So the ideal peak pressure depends on elevation and cylinder compression
> >> ratio. Using the same pressure measuring device and techniques in an 
> >> engine
> >> at operating temperature and at similar cranking speeds should provide 
> >> valid
> >> cylinder-to-cylinder comparisons. Lower peak pressure indicates air
> >> leakage-either/or past the rings, valves, gaskets, pig iron. Adjusting 
> >> the
> >> valves on a solid-tappet engine before the test makes sense-although 
> >> having
> >> them buried below 30" long ram induction intake manifolds makes that a
> >> challenging job.
> >>
> >> BTW, the ram effect is designed to increase the apparent atmospheric
> >> pressure at the intake valve while it is open. The only reference I found
> >> indicated the ram effect could amount to as much as 3 psi at resonant 
> >> speed.
> >> As our engines are limited by the amount of air they can inhale (free air
> >> capacity), a 3 psi boost at the inlet could theoretically increase the
> >> engine's power by 20% at sea level. Chrysler only claimed 8.3% (390 HP 
> >> vs.
> >> 360 for a non-ram K). This suggests a 1.2 psi ram effect. Anyone heard or
> >> measured anything different?
> >>
> >> C-300K'ly
> >>
> >> Rich Barber
> >>
> >> Brentwood, CA (Elevation at my home here in the Bay Area is about 120')
> >>
> >> Ps: Quiz: What is the theoretical peak compression pressure of a cylinder 
> >> of
> >> a C-300 hemi engine parked outside the state capitol building at Denver?
> >> (Just before the park police tow the car and arrest the mechanic) Answer:
> >> Scroll down to under Marshall's signature.
> >>
> >> rb
> >>
> >> From: Michael Moore [mailto:mmoore8425@xxxxxxx 
> >> <mailto:mmoore8425%40aol.com>]
> >> Sent: Friday, November 09, 2012 5:01 AM
> >> To: mgoodknight@xxxxxxxx <mailto:mgoodknight%40juno.com>
> >> Cc: c300@xxxxxxx <mailto:c300%40ez2.net>; Chrysler300@xxxxxxxxxxxxxxx 
> >> <mailto:Chrysler300%40yahoogroups.com>
> >> Subject: Re: [Chrysler300] Compression pressure , 300H
> >>
> >> Marshall,
> >>
> >> I have been gradually getting my 300H, which I have owned since 1964, 
> >> back
> >> into a more drivable condition. Some of the major problems which kept me
> >> from driving it much (brakes, steering) are resolved, but the engine 
> >> issues,
> >> while better, are still with me. In general, it has suffered from a lack 
> >> of
> >> power dating back to the engine rebuild I had done many years ago. The
> >> rebuilder, a highly respected race engine builder, misunderstood 
> >> California
> >> (where I was moving to) requirements. He also knew high test was going 
> >> away.
> >> Among the mods he made was to lower the compression with a custom Barnes
> >> cam, rejet the carbs with richer needles and install a smog valve.
> >> The car had power, but ran so rich your eyes burned. The carbs were 
> >> rebuilt
> >> and rejetted to stock needles and it began to run better. I know it still
> >> does not run as strongly though as it did even in the 90's.
> >>
> >> I obtained a correct 300H camshaft from a member and have a new set of
> >> lifters. My plan is to replace the camshaft with the stock 300H camshaft.
> >>
> >> Recently though, I have been wondering if the rebuilder may have 
> >> installed
> >> lower compression pistons. If so, now would be the time to replace the
> >> pistons also.
> >>
> >> I also don't fully appreciate how the custom camshaft lowered the
> >> compression ratio other than he adjusted the overlap.
> >>
> >> Thanks,
> >>
> >> Mike Moore
> >>
> >> Morgan Hill, California
> >>
> >> 300H
> >>
> >> On Nov 9, 2012, at 3:44 AM, mgoodknight@xxxxxxxx 
> >> <mailto:mgoodknight%40juno.com> wrote:
> >>
> >> Thanks for your research Rich,
> >>
> >> That's a good write-up on compression testing. One might conclude from 
> >> that
> >> reading that too much emphasis is often put on the results of compression
> >> testing and that proper (valid) compression testing is not often
> >> accomplished.
> >>
> >> Much can be learned about the condition of an engine from studying the
> >> results of a valid test, but inaccurate diagnostics are more commonly the
> >> main outcome.
> >>
> >> My recommendation is to avoid such a test unless you have strong evidence 
> >> of
> >> a problem that can be easily identified by a test. If the engine runs 
> >> well
> >> and performs properly, don't do the testing. You might see results that 
> >> will
> >> cause you undue worries.
> >>
> >> Marshall Goodknight, engine failure analyst
> >>
> >> (Answer: 88 psig-for about a 20% loss in potential power. The C-300 
> >> becomes
> >> a C-240)
> >>
> >> Please note: message attached
> >>
> >> From: "Rich Barber" <c300@xxxxxxx <mailto:c300%40ez2.net>>
> >> To: "'Michael Moore'" <mmoore8425@xxxxxxx <mailto:mmoore8425%40aol.com>>, 
> >> "'300'"
> >> <Chrysler300@xxxxxxxxxxxxxxx <mailto:Chrysler300%40yahoogroups.com>>
> >> Subject: RE: [Chrysler300] Compression pressure , 300H
> >> Date: Thu, 8 Nov 2012 22:47:28 -0800
> >>
> >> __________________________________________________________
> >> 7 foods KILL fat
> >> Surprising foods that boost your metabolism
> >> http://thirdpartyoffers.juno.com/TGL3131/509cecd8c55056cd87e56st01duc
> >>
> >> From: "Rich Barber" <c300@xxxxxxx <mailto:c300%40ez2.net>>
> >>
> >> Subject: RE: [Chrysler300] Compression pressure , 300H
> >>
> >> Date: November 8, 2012 10:47:28 PM PST
> >>
> >> To: "'Michael Moore'" <mmoore8425@xxxxxxx <mailto:mmoore8425%40aol.com>>, 
> >> "'300'"
> >> <Chrysler300@xxxxxxxxxxxxxxx <mailto:Chrysler300%40yahoogroups.com>>
> >>
> >> Individual compression pressures on a long non-operated, 85,000 mile, 
> >> cold,
> >> ram K block ranged from 100 psi to 140 psi. I found this interesting text 
> >> on
> >> analyzing compression pressures. According to the 75% criterion, the 
> >> engine
> >> failed, although a properly operated and warmed up engine with properly
> >> adjusted solid tappets would have probably tightened the range and
> >> marginally passed.
> >>
> >> C300K'ly,
> >> Rich Barber
> >>
> >> COMPRESSION TESTING
> >>
> >> Note: although this is written primarily for 4cycle gas engine testing,
> >> 2cycle gas and diesel follow pretty much the same sequence of procedures.
> >> Also, many diesel engine companies do not publish specific compression
> >> readings so the values, in the chart, at the end of this section will be 
> >> too
> >> low for use with a diesel, you'll have to do the calculation.
> >>
> >> 1. Be sure the crankcase is at the proper level and the battery is 
> >> properly
> >> charged. Operate the engine for a minimum of 30 minutes at 1200 rpm, make
> >> sure that the choke has opened, and the engine is at normal operating
> >> temperature. Putting a load on the engine for at least 10 minutes, can
> >> increase the accuracy of your test. Turn the ignition switch off; then
> >> remove all the spark plugs (injectors on the diesel). If the engine has
> >> closed cooling, (green anti-freeze) relieve pressure in the cooling 
> >> system.
> >> (carefully)
> >>
> >> 2. Set the throttle plates and choke plate in the wide open position. On 
> >> 4
> >> cycle gas engines: Try not to pump raw fuel into the intake with the
> >> accelerator pump.
> >>
> >> 3. Install compression gauge in No. 1 cylinder.
> >>
> >> 4. Install an auxiliary starter switch in the starting circuit. Ground 
> >> the
> >> coil wire on gas engines. Next, using the auxiliary starter switch, crank
> >> the engine (with the ignition switch off) at least five compression 
> >> strokes
> >> and record the highest reading.
> >>
> >> Count the approximate number of compression strokes required to obtain 
> >> the
> >> highest reading.
> >>
> >> 5. Repeat the test on each cylinder as was required to obtain the highest
> >> reading on the No. 1 cylinder.
> >>
> >> If the readings degrade from front to rear, re-check the battery and
> >> possibly re-run the test starting at cylinder #1. In this way you can 
> >> have a
> >> set of two tests to compare an average.
> >>
> >> TEST CONCLUSION
> >>
> >> 2 Cycle Engines:
> >> Your test results need to be within 15 psi range to be considered an 
> >> engine
> >> worth using. For example; a 3 cylinder with readings of 130, 135, and 120
> >> would be considered a good engine. Some might argue that there should be 
> >> no
> >> more than 5psi difference between high and low cylinders. But, obviously,
> >> the closer the readings are to each other, the better.
> >>
> >> 4 Cycle Engines:
> >> The indicated compression pressures are considered normal if the lowest
> >> reading cylinder is within 75% of the highest. Refer to the following
> >> example and chart.
> >>
> >> Seventy-five percent of 140, the highest cylinder reading is 105. 
> >> Therefore,
> >> cylinder No. 7 being less than 75% of cylinder No. 3 indicates an 
> >> improperly
> >> seated valve or worn or broken piston rings.
> >>
> >> If one, or more, cylinders read low, squirt approximately one (1) 
> >> tablespoon
> >> of engine oil on top of the pistons in the low reading cylinders. Repeat
> >> compression pressure check on these cylinders.
> >>
> >> 1. If compression improves considerably, the piston rings are at fault.
> >>
> >> 2. If compression does not improve, valves are sticking or seating 
> >> poorly.
> >>
> >> 3. If two adjacent cylinders indicate low compression pressures and
> >> squirting oil on the pistons does not increase the compression, the cause
> >> may be a cylinder head gasket leak between the cylinders. Engine oil 
> >> and/or
> >> coolant in the cylinders could result from this problem.
> >>
> >> Note: An engine compression test is easy to do but, your results need to 
> >> be
> >> tempered with the knowledge of testing conditions that reduce the 
> >> accuracy
> >> of your test. As the battery gets weaker, starter gets hotter, and the
> >> engine cools down, your results from any one cylinder will change. It is
> >> important to do the test a quickly as possible, with as little cranking 
> >> as
> >> needed to complete the test.
> >> Circumstances arise where a more accurate leak down test should be 
> >> utilized
> >> before you start tearing the engine down. Readings that are at the 
> >> extremes
> >> of the chart, (meaning over-all very high or very low readings), may
> >> indicate conditions inside the cylinders that a compression test won't
> >> depict properly.
> >> You can do the math yourself but, the following quick reference chart 
> >> should
> >> be used when checking cylinder compression pressures. ( to avoid
> >> mathematical errors) The chart (below) has been calculated so that the
> >> lowest reading number is 75% of the highest reading.
> >> Special note: Although the "actual" compression readings are not all that
> >> important, keep in mind that very few engines will run with a compression
> >> under 100 psi. However, there are some engines that will test with 
> >> readings
> >> in the 90 psi range on a regular basis. If you're not sure if you have 
> >> one
> >> of these engines, contact your servicing dealer before you get excited.
> >>
> >> Although 75% range is tolerable for an older motor, keep in mind that 
> >> most
> >> modern engines are designed at much closer tolerances. Also, on a V8 
> >> engine,
> >> if 7 cylinders test at 150psi and only one tests at 113psi, this is not a
> >> good sign...
> >>
> >> -----Original Message-----
> >> From: Chrysler300@xxxxxxxxxxxxxxx <mailto:Chrysler300%40yahoogroups.com> 
> >> <mailto:Chrysler300%40yahoogroups.com>
> >> [mailto:Chrysler300@xxxxxxxxxxxxxxx 
> >> <mailto:Chrysler300%40yahoogroups.com> 
> >> <mailto:Chrysler300%40yahoogroups.com> ]
> >> On Behalf Of Michael Moore
> >> Sent: Thursday, November 08, 2012 11:13 AM
> >> To: 300
> >> Subject: Re: [Chrysler300] Compression pressure , 300H
> >>
> >> Sorry, that would be engine compression.
> >>
> >> Mike Moore
> >>
> >> On Nov 8, 2012, at 11:00 AM, Michael Moore wrote:
> >>
> >> Does anyone have available the pressure I should read for a stock 300H 
> >> when
> >> cranking (with all plugs out) ?
> >>
> >> Thanks, Mike Moore
> >>
> >> [Non-text portions of this message have been removed]
> >>
> >> [Non-text portions of this message have been removed]
> >>
> >> ------------------------------------
> >>
> >> To send a message to this group, send an email to:
> >> Chrysler300@xxxxxxxxxxxxxxx <mailto:Chrysler300%40yahoogroups.com> 
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> >> [Non-text portions of this message have been removed]
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> >> ------------------------------------
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> >> To unsubscribe from this group, send an email to bob@xxxxxxxxxxxxx 
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> >> Links
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> >>
> >> [Non-text portions of this message have been removed]
> >>
> >> ------------------------------------
> >>
> >> To send a message to this group, send an email to:
> >> Chrysler300@xxxxxxxxxxxxxxx <mailto:Chrysler300%40yahoogroups.com>
> >>
> >> To unsubscribe from this group, send an email to bob@xxxxxxxxxxxxx 
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> >> http://autos.groups.yahoo.com/group/Chrysler300/join and select the 
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> >> Links
> >>
> >> 
> >
> > 
> 
> 
> 
> 
> ------------------------------------
> 
> To send a message to this group, send an email to:
> Chrysler300@xxxxxxxxxxxxxxx
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> go to http://autos.groups.yahoo.com/group/Chrysler300/join and select the "Leave Group" button
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> For archives go to http://www.forwardlook.net/300-archive/search.htm#querylangYahoo! Groups Links
> 
> 
> 
 		 	   		  

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