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Thread: ****Cam Guide****

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    Lightbulb Cam Guide

    III. Internals

    Preface:

    The LS1 like any other engine works as a system, treat is as one, you want to get as much air in and out as you can. The plethora of mods out there will allow you to do that. Things to consider before you start on your modding process:

    1) There is no "best" part when it comes to mods.
    2) When you want to start modding your car come up with a tangible plan.
    3) Do not go into modding blindly; you will end up wasting money, time, and effort.
    4) Do your research before you buy mods.
    5) Find out your states/counties emissions requirements before choosing mods
    6) Be realistic on what your going to do with your car
    7) Usable power under the curve is what you want to shoot for, do not just look at peak gains
    8) Work within your budget
    9) If your are still under warranty Contact your own dealership and discuss your warranty and modding issues.
    10) Work on matching your parts well, meaning:

    - do not buy 2500+ stage 3 heads that flow 330cfm@.600 if you have a stock cam or very low duration/lift cam (i.e tr220)
    - LSX intake and 90mm TB for a basic bolt on car
    - dont run 230+ cams on stock manifolds or shorties
    - dont run a big cam and a small stall (i.e tsp231 and a vig 2200)
    - dont over/under gear your car (i.e tr230, a4, 2.73's)

    (Credit given where applicable. Info/pics taken from personal experience, around the Internet, and ls1tech/ls2.com.) Special thanks to the guys on ls1tech (J-Rod, JMX, ect)


    A. Cams

    What they are:

    What they do: Cams are the ďbrainĒ of your engine and dictate how your engine will perform; power, idle quality, valve events, ect.

    What to look for:

    - Get a basic understanding of cams before purchasing. Itíll also help you understand the info/advice that is given on the boards.

    - ALL gains are relative to your own setup

    1) For example if you installed S2 heads and a tsp231 cam and only put down 390rwhp tuned donít fret if you started with a base of 290rwhp.

    - When researching cams look at the average gains. Donít look at the highest gains you see (395rwhp with say and ls6 cam) and expect to get the same results when the average is 360-380rwhp depending on setup

    - Can a cam be your first mod; yes. Should a cam be your first mod; no.

    1) Cams need to breath, that means a complete intake and exhaust setup. The bigger the cam the more prevalent those mods become.
    2) A4 guys; match your stall and cam appropriately

    - Donít be afraid of older or smaller cams (T1/B1, tr220, comps 218, ect). They might not use the latest and greatest lobe technology or break speed records but they are proven cams and are great for the guys looking for 400 > * rwhp cam only.

    - Take Internet reviews of cams with a grain of salt and use them as reference only. Contact your local fbody club or ask around your local regional forum and find as many guys who have cams as you can. Hear and drive/ride along with as many different cam setups as you can. The reason for this is everyone has there own idea of what streetable is since that is a RELATIVE term. Decide on your own what streetable is to you

    - Donít let someone talk you into a cam if it doesnít meet your requirements and fit your specific applications and goals.

    - Keep in mind there is more then one way to make the same amount of power

    - If you have the sniffer for emissions either go with the cam of your choice and pray you find a good enough tuner and have luck on your side or keep the duration 226 and under on a 114 and a decent tune and you should be fine.

    - When buying a used cam ask for the cam card and/or serial numbers. Take that serial number and email or PM the company or board representative with that serial number. They will be able to tell you if in fact it is one of there grinds and if itís the one you had planned on purchasing. That is the only way short of having the cam specíd on a cam doctor to know exactly what cam you are buying. Here's the serial number from my old TR230.

    - Donít get caught up in peak HP. These are ls1 boards not Honda boards . Under the curve power is where itís at.

    - To make things easier most sponsors offer cams as a package deal that includes all that youíll need for an installation. Here was my old cam kit.




    I. Cam Overview:

    -

    - Your starting point:

    Stock 98-00 trans am cam

    Duration@.050 198.86 intake 209.25 exhaust
    Lift .498 intake .497 exhausts
    LSA 119.45

    Stock 01-02 trans am cam

    Duration@.050 196.37 intake 208.72 exhaust
    Lift .464 intake .479 exhausts
    LSA 115.92


    When buying a cam it comes with a cam card. This card gives you the exact specs of the cam. Here is an MTI/Lunati B1 cam card and a LGM G5X2 cam card.


    A. Duration:


    - The amount of time (in degrees) that lift is generated is called the duration of the lobe. Camshafts operate at half engine speed. This is easy to see because the gear that turns the camshaft is twice the diameter of the crank gear that drives it. That means that the cam spins at half engine speed. Because of this, camshaft duration is always expressed in crankshaft degrees. This makes it easy when it comes time to degree the cam to ensure it is positioned accurately in the engine.

    - As you can see in the 2 cam cards there is duration @ .050 and duration @ .006. Duration @.050 is pretty much industry standard and thatís what youíll see when looking at cam specs from the various sponsors and what most people are talking about when discussing duration

    - Duration @.050 and Duration @.006 is a way you can determine the difference between two or more cams with the same given duration at .050. For example a TR224, TSP 224, and Comps 224. The lower the duration @.006 the more aggressive the ramp rate. The more aggressive the ramp rate the more overall and under the curve power.

    - If you know the advertised duration (.006) of a cam you can calculate the ramp rate. To do this you take the duration @.006 and subtract it from the duration @ .050. A number of 53 or higher denotes an XE lobe or other mild lobe and a number of 49 or lower denotes an XE-R lobe or other aggressive lobe (Beast and 99 Black Bird T/A )

    - Using the B1 and G5X2 as examples is as follows:

    B1: 281 (.006) Ė 221 (.050) = 59

    G5X2: Intake 281 (.006) Ė 232 (.050) = 49
    Exhaust 289 (.006) Ė 240 (0.50) = 49

    - Most cam companies use Comp lobes; either an XE or XE-R, the later being the more aggressive of the two. TR uses its own proprietary lobe and FMS uses Cam Motion lobes.

    - Intake opening (IO) usually occurs before top dead center (BTDC), while intake closing (IC) happens after bottom dead center (ABDC). For the exhaust side, exhaust opening (EO) occurs before bottom dead center (BBDC) and exhaust closing (EC) after top dead center (ATDC). These data points are listed on the cam card that comes with each new cam.

    - Traditional Splits refers to more exhaust duration and lift then intake (tsp231/237, g5x2 232/450, ect). Reverse split refers to more intake duration and lift then exhaust (TR 230/224, X1 230/227). Single patterns are defined as having both the same intake, exhaust duration, and lift. (TR224, TR220, FM4 226/226). Which cam is better depends on your application.

    - GREAT technical discussion on cams started by J-Rod from ls1tech: here

    - Valve Events (VE) calculator can be found here

    - Other good technical shit can be found here and here and here



    B. Lift:



    - Lift is defined as the difference in height between the radius of the circle and the height of the eccentric. This is called lobe lift.

    - When viewing cam specs the lift portion is the gross lift, meaning its calculated with the 1.7 stock rockers.

    - To get the lobe lift you take the advertised (gross) lift and divide it by 1.7. If you follow the B1/X2 cam card youíll see that they list both lobe lift and gross lift.

    - If you want to add higher ratio rockers and want to know your new lift you do the following using the B1 as an example:

    .559 / 1.7 = ~.329, you then take that lobe lift and multiply it by whatever rocker ratio you want. With SLP 1.85 rockers your new lift specs become .329 X 1.85 = ~ .609

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    C. Lobe Separation Angle (LSA)



    - LSA is defined as spread in camshaft degrees between the intake centerline and the exhaust centerline.

    - Overlap is the number of crankshaft degrees that both the intake and exhaust valves are open as the cylinder transitions through the end of the exhaust stroke and into the intake stroke

    - LSA is ground into the cam and cannot be changed without grinding a new cam

    - Bigger duration cams will have more overlap then a smaller duration cam even if both are on the same LSA.

    - The key to making overlap work is maximizing the power in the rpm band where you want it.

    - Long overlap periods work best for high-rpm power. For the street, a long overlap period combined with long-duration profiles combine to kill low-speed torque

    - Reducing overlap on a long-duration cam will often increase midrange torque at the expense of peak power, but if the average torque improves, thatís probably a change worth making.

    - Many enthusiasts purchase a camshaft strictly on the basis of how it sounds. A cam with generous overlap creates that distinctive choppy idle that just sounds cool.

    - Youíll find that a 112 or 114 LSA with a 108 and 110 ICL respectively is the best all around street setup.

    - While doing my research on the T1 I cam across this dyno in which if I recall Tony (Nineball) stated that the blue graph was a T1 (112 lsa) and the other 2 where a B1 (114) lsa. 112 vs. 114

    - What really affects where the cam makes the most power is the intake timing events. What affects drivability most is the exhaust-closing event.


    D. Advance and Retard:

    - When you see cams specs like 224/224 .563/.563 112+4; the +4 denotes that the cam has 4 degrees of advance ground in.

    - Most off the shelf cams have 2 or 4 degrees of advance ground in. This lowers the power band slightly and offers more low end and midrange at the sacrifice of a bit more top end power

    - For cams used primarily on the street the advance is best appreciated. For a strip or racing setup 2 or 0 degrees advance will net you more peak power in the upper ranges of the power band

    - To find out if you cam has advance ground in you can check on the cam card. Besides the +2, +4, you can determine the number by looking at the intake center line (ICL). Referring back to the B1 cam card youíll see that it states that those are the specs when installed on a 108 ICL.

    - Subtracting the ICL from the LSA will give you the advance: 112 Ė 108 = 4 using the B1. Or 113 Ė 109 = 4 using the G5X2.

    - Retarding the cam does the opposite of advancing it, it pushes the power band up slightly and gives more top end power.

    - With an adjustable timing chain or degreeing the cam you can install the cam at different ICLís.

    - Keep in mind as stated; most cams already have advance ground into them so if you buy an adjustable timing chain and advance 2 degrees youíll increase the overall advance to 6 degreeís if the cam has 4 degreeís ground in.

    - Also with big cams and/or milled heads piston to valve clearances starts becoming an issue. If in doubt always clay the heads and find out your PtV clearance before installing/advancing especially if your cam has a big intake duration as advancing starts the intake valve events sooner.

    - Installing dot to dot or degreeing at the said ICL is the best bet.




    II. Which cam is right for you


    - The key to cam selection is to be brutally truthful when it comes to how you intend to use the engine in question.

    - Donít succumb to the temptation to put the biggest cam you can find into your daily driver.

    - If you want to be a lazy fuck and not do your own research to find the cam that best suits your application you can just pick up a tr224 114 cam which is the quintessential all around great daily driver cam.

    - Pretty much any 220 to 230 duration, .550 to .590, 112 or 114 cam is considered relatively small and great for a daily driver application with the right tune.

    - A few of the more popular and latest and greatest cams in no particular order:

    TR224 .563/.563 112 +4
    TR 224 .561/.561 114+4
    Comps 224 .581/.581 112
    TSP 231/237 .598/.595 112 (unsure of advance)
    G5X2 232/240 .595/.609 112 or 114+4
    G5X3: specs unreleased but bigger then the X2
    TR Trex 242/248 .608/.612 110+2
    FMS FM4 226/226 .575/.575 112 or 114
    FMS FM 10 228/228 .581/.581 112 or 114
    FMS FM 13 230/232 .591/.585 112 or 114
    02+ LS6 cam 204/218 .551/.547 117.5
    LPE GT2-3 207/220 .578/.581 118.5
    GM HotCam 219/228 .525/.525 112
    TSP 225/225 .589/.589 112
    TSP 233/ 233 .595/.595 112


    II. Valvetrain


    A. Springs


    - For any cam swap you MUST change out valve springs. The stock springs are only good enough for the stock cam and barely at that.

    - As far as springs go you have a few but not limited to the following choices:

    1. Comp 918ís: A few years back they had some problems with non-blue stripe springs breaking but they have seemed to rectified the problem. The beehive design is also a superior setup. Your stock steel retainers can be reused with the 918ís but titanium retainers are recommended for lightening up the valvetrain and for strength.

    Outside Diameter (O.D.): 1.290"/1.060"
    Inside Diameter (I.D.): .885"/.656"
    Installed Pressure: 130 lbs @ 1.800"
    Open Pressure: 318 lbs @ 1.200''
    Coil Bind: 1.085"
    Maximum Lift: 0.625"
    Rate (lbs/in): 313 lbs/in


    2. Manley Nextek: Also a single spring like the 918ís but not of the beehive variety. They are a good spring and come in a package deal from SDPC for 178 and that includes titanium retainers. The springs are rated for up to .600 lift.

    Max Valve Lift : .600"
    O.D. : 1.255"
    I.D. : .830
    Installed Pressure : 115@1.750"
    Open Pressure : 350@1.175"
    Coil Bind : 1.100"


    3. Crane Duals: A dual spring setup rated for up to .650 lift. When buying duals youíll need the dual springs (obviously), titanium retainers, new dual spring seats, and new valve stem seals.

    The installed seat pressure is 112 lbs @ 1.800'' with a maximum recommended lift of .650'' at the valve with an accompanying open pressure of 352 lbs. The 1.275'' O.D.

    112lbs @ 1.800
    352lbs @ 1.150
    will handle .650 lift with .045 coil clearance

    *INFO REGARDING CRANE SPRING REVISION*


    4. Comp 921ís: Also a dual spring like the Cranes above and come as a kit with everything you need for installation, rated for up to .650 lift

    O.D: 1.300
    I.D: .870 (outer spring)
    I.D: .655 (inner spring)
    135 LBS @ 1.770
    400 LBS @ 1.220
    COIL BIND @ 1.040
    MAX LIFT .650


    5. Patriot Gold Duals: See Crane and 921ís. The PP Golds are currently the best direct drop in spring, they are the stand set for the new AFR heads and come on all PP heads. PP are the only genIII spring setup to use the super 7 locks.

    O.D 1.29
    135lbs @ 1.800
    385lbs open
    coil bind @ 1.08
    .650 lift

    My Personal Indepedently tested PP golds:

    seat: 143 lbs @ 1.800
    open: 363 @ 1.200
    coil bind: 1.060
    Clearance: .140
    spring rate: 367


    6. PRC Dual Spring Kit: Kit comes with Dual springs, tit. retainers (using stock locks), seats, valve stem seals. good for up to .660 lift

    seat : 140lbs
    open: 390lbs
    install : 1.800
    coil bind: 1.07
    1.290 O.D.
    max lift : .660
    matl : super pure chrome silicone


    Comp 977's: dual spring (requires machining of spring pockets)

    O.D: 1.46
    I.D: .700
    seat pressure: 155 @ 1.850
    open presure: 419 @ 1.250
    coil bind: 1.195
    spring rate: 441

    Comp 978's: Dual springs (requires machining of spring pockets)

    O.D: 1.46
    I.D: .697
    seat pressure: 126 @ 1.850
    open presure: 368 @ 1.250
    coil bind: 1.195
    spring rate: 403

    Comp 987's: Dual Springs (require maching of spring pockets)

    O.D: 1.430
    I.D: .697
    seat pressure: 121 @ 1.800
    open presure: 388 @ 1.200
    coil bind: 1.150
    spring rate: 344



    B. Pushrods


    What they are:

    What they do: transfer the motion of the cam to the rockers

    What to look for:

    - New pushrods arenít absolutely necessary but they are highly recommended.

    - The pushrod was never designed to be a fusible link in the valvetrain. Several years ago we even had a member (might have been in the old LS1.com days) that was an engineer from Jesel (don't recall his ID) and he was adamantly opposed to the notion that the LS1 pushrods were designed to break in the event of a mechanical over-rev. The job of the pushrod is to accurately transmit the motion of the cam lobe (via the rocker arm) to the valve. If itís flexing under load, then its simply not doing its job.

    Look at it this way; you CAN mechanically over-rev any engine - pushrod, OHC, rotary, or otherwise - and cause damage. There is nothing unique or special about the LS1 pushrods making them fusible.

    This is like saying that you broke your ring gear on a missed shift so therefore everybody should continue using the weak 10-bolt rear ends. Just a silly, backwards argument IMO - especially when you're considered an aggressive cam with heavier valve springs (Fulton 1)



    C. Rockers

    What they are: HS 1 HS 2 Comp Magnums Comps Crane SLP 1.85

    What they do: transfer the cam motion along from the pushrods and accentuate the valves to open

    What to look for:

    - New rockers are also an optional choice during a cam install.

    - The stock roller tip rockers have been known to loose there bearings but itís not an overly common occurrence.

    - With companies like Harland Sharp coming out with affordable high quality roller rockers it makes the choice to upgrade that much easier

    - Yellow Terraís (YT) are also a relatively economical choice for roller rockers

    - Adjustable rockers allow you to adjust lifter pre-load

    - Higher ratio rockers can be used to increase lift (see cam lift for more info). Along with increasing the valve lift adding higher ratio rockers also nets you an extra degree or two of duration and increased overlap.


    D. Others

    - Itís a good idea to install a new timing chain as well. The stock ones are notorious for having a lot of slack in them
    - You can either get a single or double
    - The double chains come with the needed spacers to clear the oil pump
    - 98-00 cars should also factor in a new oil pump
    - A new chain and oil pump should run you about 200 dollars



    III. HOW TO INSTALL

    - JMX is the muthafuckin man, thatís all you need to know
    - Install Guide
    - I along with countless others have followed that guide for cam installs (among other things). If you can turn a wrentch, have some basic knowledge, and follow that guide you can do your own cam install.
    Last edited by jrp; 02-23-2005 at 08:55 AM.

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    IV. Tuning


    - Factor in tuning from the get go. If you cant afford tuning then just hold off on the install until you can. Its not going to kill you to wait a bit to save up the 350-500 for the dyno tuning.

    1) This is especially true when installing big cams, the bigger the cam the harder it is for the stock PCM to compensate.
    2) Smaller cams can get away with stock tuning longer then bigger cams but even so all cams can benefit from tuning
    3) A DYNO IS A TUNING DEVICE; NOTHING MORE, NOTHING LESS
    4) Tuning is more then just looking for more HP. It makes your car more livable and drivable by dialing in your a/f ratio, deleting codes, helping with hot and cold starts, getting your idle set straight, ect.

    - Of course if you have your own copy of hptuner/editor/predator you can do the tuning yourself.

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    Cam Glossary

    asymmetrical: one cam lobe with differing opening and closing ramp rates; it projects different images on either side of the lobe centerline; many modern cam grinds have asymmetrical lobe patterns, often with high opening rates using roller lifters, which allow their use

    base circle (heel): lowest point of the cam lobe in relation to lift; the closed valve position occurs as this portion of the cam lobe turns against the lifter. All valve lash settings are made when each lobe has the base circle (or ďheelĒ) against the lifter (or lash pad on some OHC engines). When a camshaft is being ground, the base circle is the actual part of the lobe that is ground to form lift at the lobe

    basic rpm: the rpm range in which the engine makes the best power

    cam centerline: cam phasing in relation to the crankshaft; where the centerline of the intake or exhaust lobe is in relation to the No. 1 cylinderís piston given in degrees of crank rotation after TDC. When degreeing a cam, you must know this figure to install it properly. When you do advance or retard the cam centerline (when degreeing a cam), you affect both intake and exhaust lobes; these are not individually adjustable

    degreeing a cam: setting the camshaftís phase (or position) in the engine in relation to crank position. Most cams today are ground with some advance to make up for timing chain stretch, around 4 degrees. If the installer places the cam ahead in relation to crank/piston timing, it has been advanced; if itís moved back from straight up, itís been retarded. Many people used to install a cam advanced, but since most are already ground slightly advanced, thereís usually no need. Always follow the manufacturerís installation card or instructions carefully


    duration: time (in degrees of crankshaft rotation) that the valve is open during its tappet lift; given in ďadvertised durationĒ and at 0.050-inch tappet lift; when comparing cam specs, always compare duration figures at 0.050-inch lift because cam companies measure advertised duration differently

    hydraulic cam: a cam using lifters that has a valve-controlled plunger inside its body, preloading the pushrod at the closed valve position through oil pressure lift: distance the valve is depressed from its seat when closed to the peak valve lift when open fully

    lobe separation: actual spacing of cam lobe centerlines (in degrees) for a common cylinder; ground into camshaftónot changeable; largely responsible for the idle quality of an engine; narrow separation angles seal a cylinder for a longer period of time but also give a rough idle quality, while larger angles generally give a smoother idle in street engines

    mechanical (solid) cam: a cam using lifters with only a radiused contact face in which the pushrod end sits without internal valves or other complexity; requires periodic lash setting

    nose: full-lift portion of the cam lobe where the lifter is pushed open at maximum distance

    ramps: portions of the cam lobes that lift or settle the lifter from the base circle of the cam; does not include the nose. They have different rates of lift in velocity and degrees of crank rotation. Symmetrical cams have individual lobes with the same opening and closing ramp rates, while asymmetrical cams have different opening and closing rates on the same lobe. Roller cams can use more radical ramp rates because of the nature of the roller lifter


    roller cam: in either hydraulic or solid versions, these cams use lifters that employ wheels to contact the camshaft lobes, fixed in needle bearings; these cams often have higher valve opening rates than flat-faced cams and exhibit less friction; most roller cams require using a bronze distributor drive gear due to metallurgical differences in flat-faced and roller cam material, though some new ones do not. Rollers have been widely used in diesel and motorcycle engines previous to automotive gasoline engines

    split duration (dual pattern): cams with intake and exhaust lobes of different specs

    symmetrical: both sides of one cam lobe are mirror images of each other; they have the same ramp rates upon opening the valve and closing it; split evenly on either side of the individual cam lobe centerline


    - CHP

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    Cam Chart



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