Camshaft

From 3.8Wiki

[[CAMSHAFTS EXPLAINED]]

WHAT GIVES A CAM ROUGH OR LOPEY IDLE? The reason most want the lopey idle is because race cars usually have a rough idle and we want our cars to look and sound like race cars. The reason race cars have that rough idle is because the engines used are designed for high-rpm operation. To get the air/fuel mixture in the engine and the exhaust out at high rpm, race cars need a camshaft with as much lobe lift and as many degrees of duration as possible and a narrow lobe-separation angle(LSA), which results in valve overlap. A cam like this has extremely poor idle quality the engine wont run below 2000 rpm but idle quality doesnt really matter on a race car.

(Added by Bill) If I can add to this discussion relative to cam lope: The component I think is missing in the discussion is the concept of the intake plenum with the cam overlap. Within the plenum (engine at slow speed), when the intake and exhaust valves are open at the same time (overlap), the exhaust gas bleeds into the intake, interupting the flow, and also diluting the intake air with exhaust gas. The immediate effect is to cause that cylinder to "stumble". This will disrupt the smoothness of the engine by having random cylinders getting a poisened intake charge, either by flow interuption, or gas dilution. In the days of carbs, the flow interuption would actually have the fuel droplets drop out of the air stream to the bottom of the port.

Why increased duration leads to weak low RPM performance (added by atlstang)We know that high durations lead to weak lower rpm performance and stronger higher end performance. But some questions may rise like why? and is there a limit to how far we go? Cam is to the intake as pb is to j, so it can be argued that part of the gains could be from intake tuning but even with the intake factors absent it is seen that the relation between high and low rpms still holds. The key is inertia. Air is like a very light weight bus traveling down the road, the faster this bus is traveling the more it will take to stop it. Like the bus when air is traveling fast(higher rpm) It will not want to stop and will continue to fill the cylinder well into the compression stroke. But at lower rpms the air will stop easier/sooner and begin to reverse back the other way if held open to long causing thus causting the lope sound as described

Overlap is the period that the intake and exhaust valves are open at the same time. Basically what you are hearing is the fresh intake charge going out the exhaust port. Kind of like a vacuum leak.

CALCULATING OVERLAP The amount of overlap is what causes your "rough idle". You can figure this with this equation: Intake duration + Exaust duration, divided by 4, - LSA, x 2. The more overlap, the rougher the idle. so for these SSMS cams you can predict how they will sound for the most part although tuning and ci does play a factor... 210/226 compcam#44-703-9= -12 218/224 ssms billet cam= -3 218/226 compcam#44-704-9= -2 224/230 ssms billet cam= -1 224/232 ssms regrind cam= 0 236/244 ssms billet cam= 12

MYTH 1: higher lift means bigger lope...FALSE!!!!! MYTH 2: higher LSA means bigger lope...FALSE!!!

WHAT IS LIFT? Lift refers to maximum valve lift. This is how much the valve is "lifted" off its seat at the cam lobe's highest point. The intake and exhaust valves need to be open to let air/fuel in and exhaust out of the cylinders. Generally, opening the valves quicker and further will increase engine output. Increasing valve lift, without increasing duration, can yield more power without much change to the nature of the power curve. However, an increase in valve lift almost always is accompanied by an increase in duration. This is because ramps are limited in their shape which is directly related to the type of lifters being used, such as flat or roller. WHAT IS DURATION? Duration is the angle in crankshaft degrees that the valve stays off its seat during the lifting cycle of the cam lobe. Increasing duration keeps the valve open longer, and can increase high-rpm power. Doing so increases the RPM range that the engine produces power. By increasing duration without a change in lobe separation angle will result in increased valve overlap WHAT IS LSA? LSA is the Lobe Separation Angle or the number of degrees between the intake and exhaust lobe centerlines. The LSA has a direct relationship to amount of overlap on a cam. Cams with identical duration and lift specifications can have very different LSAs. Generally speaking, a wide LSA will produce greater low end torque and a narrow separation angle will produce better top end power. For any given LSA, an engine will give similar torque curves and peak torque RPMs even with different overlaps.

CAMS

Cams are a good source of engine power and are also good for changing the exhaust note for those of you who like the throaty sound..the install can be a little $ so its recomended that you do H/I/C all at once...The price can range from 200-400 depending on type and company.

[edit] Cam installation constitution:

Go by tightening sequence of all bolts in manual 

Tools needed to complete the job:

complete metreic & SAE socket set for both 3/8's and 1/2 (both regular and deep sockets are nice)
crank pulley remover
cam lube
valve spring compressor(I'll include my design for a better valve spring compressor than the rental from autozone)
spark plug adaptor with air hose that threads into it with compressor hose hook up on the end. (not needed but 
if you dont feel like figuring out what tdc for each cylinder is it helps)
set of metric wrenches
set of torx drivers
Set of Alan wrentches
flat head screw driver
gaskets (upper intake, lower intake, and timing cover, head gaskets)
gasket sealer(the black type)
thread lock
Torque wrench
aproximently 6 Qt's of motor oil (good time to switch to synthetic if you havent already done this)
coolant (you can reuse the old stuff if it doesn't get dirty)
Ziplock bags(to keep track of the bolts)
A sharpey ( to write on the bags were the bolts go)
It helps to have the following:
impact gun
prybar
compression checker
cam positioning sensor adjustor (Not needed if you find tdc using the crank pulley) 
easy outs and drill bits (in case you brake a bolt or two)
sombody that has done simular work before

Specifications:

Firing order=1-4-2-5-3-6

Camshaft sprocket bolt 30-36 ft-lbs

Camshaftthrust plate bolts 72-120 in-lbs

Timing cover to block bolts 15-22 ft-lbs

Waterpump to timing chain cover bolts 15-22 ft-lbs

Oil pan bolts 84-108 in-lbs

Rocker arm bolts 29 ft-lbs

Intake manifold to cylinder head bolts 108 in-lbs

Crankshaft damper bolt 103-132 ft-lbs

Valve cover bolts 72-132 in-lbs

Mmmk lets get to it.

1.) Park your car somewhere covered cause it wont be moving for a day or so.

2.) Jack up front of car and place on jack stands (only needed for draining fluids)

3.) Drain all fluids including coolant and remove oil filter. ( now if you cant find anything to cover the in and out tubes of the radiator we found a condom fits nicely over them)

Note: Pull the connector out of the inertia switch in the trunk.

4.) Disconnect battery

5.) Remove serpentine belt

6.) Remove intake and label connectors.

7.) Remove plugs and wires and turn the engine over so #1 cylinder is at TDC. I found a little orange dot on the harmonic balancer that matched up with a pointer on mine when it was at TDC.

8.) Pull upper and lower intakes off and put appropriate bolts in plastic bags and lable them (do this with every step) If you've not deleted your EGR you'll need to disconnect that as well. (take the fuel rail off in this step as well. What i did was layed a towel on my windshield and just let it sit up there still connected to the fuel line.)

9.) Unbolt the A/C assembly from the block and tie off to the passenger side to get it out of the way.

10.) Do the same with the power steering pump. (if you remove your battery the battery box is a great place to set the power steering pump)

11.) Remove the valve covers. (from now on be careful not to drop anything in the engine that is unretreivable)

Ok now your engine bay should look like this. (minus the PS pump still in place [chaoticdismay: my fingers are in teh picture! lawl])

(you can see the orange clamp we used to hold the A/C compressor to sheet metal in the engine bay.)

12.) Mark the relation of the camshaft position sensor housing to the timing cover with a sharpie. Then mark the position of the little nub on the inside exactly to where it is on the housing. (There should be a notch where a magnet sits when you take the cover off the CPS. If the little tab of metal is not centered or near centered in that notch you are not in TDC)

Cam position sensor and housing.

13.) Find a box, cut 24 holes in the box small enough to shove a bolt through. Take the rocker arms off and assemble them in order on the box to keep a referrence as to which cylinder/intake or exhaust rocker arm they are. Do the same with the push rods. The bolt on the rocker arms is a 1/2" bolt head.

14.) Remove the lifter hold down plates and put each lifter in a bag and label it with exhaust or intake and which cylinder it is. (no need to soak the lifters as they will not be out of oil long enough to warrant any lubrication you might need)

Brown lifter hold down plates

15.) Unbolt the header bolts and disconnect the headers from the heads. The one bolt in the back by the brake booster is exceptionally a giant pain in the ass.

16.) At this stage since your heads will come with springs already installed. You can remove the heads. I would highly recommend a breaker bar as these mother ****ers are on tight as ****. Work each bolt in the order the haynes manual says to. As to avoid warping the head.

17.) Head installation is fairly straight forward. Whip out your hanes manual and go by exactly what they say (assuming you're not using reusable head bolts.) its important so you dont blow gaskets or have any head lift.

An extra set of hands is nice for head installation as get the bolts to yield takes a lot of muscle.

Good now that you have the heads installed we can start to work on the cam which takes way less muscle than the heads lol.

L.) remove the radiator/ fan assembly and the radiator overflow tank.

M.) Unbolt the hold down washer on the cam position sensor and pull the sensor/ shaft/ gear assembly out and set aside.

N.) Next you'll need to pull the water pump off.

O.) Remove the crank pulley and sensor be sure you have that big ass washer out of the hole before you put the duck's foot on. I did this a couple of times and couldnt figure out why it wasn't pulling the pulley off.

P.) Unbolt the timing cover Do not forget about the allen wrench bolt on the front of the timing cover thats behind the oil pump. You do not need to take the pump off to get to this bolt. It might take some gentle prying to get the black rtv to break free. Dont mar any mating surfaces in the process. (this is a good time to inspect you front main seal and see if it needs replacing.)

Now you'll come to a what looks like this.

or wait was it this...

Everything that has to do with the cam gear and crank shaft woodriff key and cam woodriff key should be vertically aligned. As you can see the holes in the cam drive gear are nearly verticle. If you need to turn the crank just put the pulley on a little dont tighten it down and you can turn it that way.

18.) If you can see the tensioner has a small hole in it. If you can force the tensioner all the way back you can insert an allen wrench into it and it will hold the tensioner so the chain has slack.

19.) Remove the hold down bolt and washer from the cam end.

20.) Now pull the crank gear cam gear and chain all together. From this point note what position the cam woodriff key is in. Also note which way the cam position sensor gear is oriented.

21.) After you've pulled all the gears and chain you should be left with the cam shaft w/ woodriff key and a plate with star ended bolts that are holding the camshaft in place. You need to remove this retainer plate so you can pull the camshaft out.

22.) When removing the cam shaft be very careful not to nick or gouge the camshaft bearings or you'll be up **** creek without a paddle.

Now take this time to tear a phone book in half.

And drink a beer.

23.) Now that the cam is out look at your new cam and see if it has a woodriff key and a spacer ring. The spacer ring is behind the woodriff key. If your new cam doesnt have any of that then swap them over from your old cam. The woodriff key keeps the spacer ring on the camshaft.

24.) Break out your handy dandy engine assembly lube and lube up the first bearing circle, 4 lobes, and the next bearing circle. Then carefully slide the cam in being careful not to nick the bearings again. Once you get the second bearing lobe into the front of the engine stop. Be careful the engine is slightly angled down so the cam will want to slide in still and will fall and damage the bearings. So as you're holding the cam lube up the next 4 lobes and the next bearing lobe and slide it in to that one. Repeat for the final segment.

Congrats you cam is now installed test it out! Wait... drink a beer!

25.) Bolt the hold down plate back up and re-orient the cam as it was with the stock one and reinstall all the gears and timing chain.(If you're gonna replace your tensioner now is the time to do it. I believe its just held on with 2 bolts if i remember correctly. Now you can tighten down the bolt and washer at the end of the camshaft. (remember tighten everything to spec)

26.) Now you're free to clean the mating surfaces of the timing cover/oil pump combo and liberally apply ammounts of black rtv. Re-install the timing cover and bolts that hold it down.

27.) Re install the crank pulley and torque to spec.

28.) Rtv around the bolt shafts that stick through the timing cover as these are prime spots for water to leak when you put the water pump on.

29.) Re-install the water pump.

30.) Reinstall your cam position sensor assembly and make sure all your marks line up. <=== very important.

Now to the fun part.

31.) put the lifters and hold down plates back on according to how you labeled them. Break out your high temp moly grease that disolves in oil and put a dab oh grease on either end of the push rods and put them in their appropriate places. Put a dab of grease on all of the valve ends as well.

32.) Clean up the threads on the rocker arm bolts and tighten them down until finger tight. (its not really important at this point as you'll be adjusting them in a second)

33.) Make sure your #1 intake is on the base circle of cam lobe and then tighten the rocker arm bolt down to 0 lash. That is where you no longer have any up and down play and its hard to spin the rod with your fingers. You should be able to do this by hand without a socket wrench.

34.) Break out your torque wrench with you 1/2" socket and set it to 25 ftlbs now tighten the bolts down. You should be getting to 25 ftlbs in 2/3- 1 1/3 turns of the bolt. If you have to turn it more you need to add shims, if you turn it less you need longer push rods. Do this for the rest of the rocker arms but Make sure you are on the lobes base circle

35.) Once that is done bolt up your headers (with new gaskets of course) Put in new spark plugs (do it now so it's easier) Put your valve covers back on.

36-end) Re-install all sensors, radiator/fan/overflow, lower intake, fuel rail, upper intake, A/C, PS pump, intake and whatnot. Add oil and coolant re attatch battery.

Attempt to fire up car. "Car wont start" Yell "GOD ****IT"

Remember that you didnt connect the inertia switch. Try again. IT STARTS!

If for some reason your car ends up like this.

You're doing it wrong.

Apply tune. Enjoy

--bigez0817 14:15, February 6, 2008 (CDT)