Part 1
In a series of posts I will try to demystify cams and there terminology for forum users. Now I know there are some very knowledgeable forum members that have probably forgotten more about cams than I will ever know, but this is written for the less experienced forum members so that they will feel comfortable selecting and correctly installing a higher spec cam for their engine. Sometimes what I have written will appear to be a little over complicated but bear with me as I maybe trying to demonstrate some practical application of a thoery other times it may be a little to oversimplified but that is to ensure all users will understand irrespective of their knowledge/experience level. First I'll discuss some common terms and their meanings that I will use. This not intended to be exhaustive but the common terms I will use in later posts.

Terminolgy:

Valve train: In a pushrod engines the valve train comprises of the cam, the lifter, the pushrod, the valve its spring & spring retainer and colletts, and for this discussion the timing gears.
Base circle: the section of the cam that doesn't have the lobe section.
Lobe: the lobe is the section of the cam that lifts the lifter and hence the pusrod and valve rocker, which ultimately thru simple lever design pushes down on the valve.
Cam Lift: lift is the total deviation the cam lobe profile makes from the base circle of the cam to the top of the cam.
Valve Lift: It is the total lift that is activated on the valve, it is the cam lift multiplied by the leverage of the rocker ratio, it will be the theoretical total movement of the valve.
Cam flanks: the section of the cam between the lobe and base circle, flanks are designed to start lifting the valve train gently and accelerate the valve train smoothly and then to lower the valve gently on the seat, this to ensure the valve doesn't pound out the valve seat and the lifter does not chatter on the cam. 
Lifter: A bucket device that sits on the cam and reacts to its profile. In the case of chrysler (Except some early engines) these are self-adjusting hydraulic lifters that use trapped engine oil thru a preset bleed, to vary the length of the lifter to ensure that no slack and hence no noise is in the valve train.
Pushrod: (its name says it all) motion transfer device
Rocker: a simple lever that transfers the lifting motion of the pushrod to downward motion on the valve stem. Most rockers are constructed to increase the leverage and this is called rocker ratio. Hemi 6 rocker ratio is 1.73:1 and small block is 1.5:1
That is the rocker ratio increases the cam lift.
ValveSpring: A wire wound spring whose task is to keep the valve closed at all other times that the valve train is not trying to open it, and to ensure that the valve train operates smoothly and the lifter always follows the cam lobe, and the to ensure the lifter does not launch from the tip of the cam lobe. Typically bigger cams will accelerate the valve train more violently to achieve higher lifts and this will try and cause the valve train to 'lift off the cam' as it changes direction at the top of the lobe. To prevent this most cam manufacturers recommend a heavier valve springs to keep the valve train in order.
Valve Float: Is when the valve train is out of sync with the camshaft, usually as a result of weak or under rated valve springs or the engine speed exceeds the springs capacity to keep the valve train firmly on the camshaft. When it occurs the valve train stops following the camlobe and the lifter or pushrod or valve or all of them are bouncing. If left unchecked it will typically lead to engine damage or destruction.
Cam Duration: Is the period measured in crankshaft degrees of rotation that the cam and hence the valve train is off the cams base circle, put simply the time the valve is open. Cam duration is typically shown 2 ways; advertised duration and at 0.050" duration. Advertised duration is anytime the valve lifter is being moved by the camlobe. The at 0.050" duration is more useful as it shows effective duration and it is easier to compare the relative performance potential of different camshafts. The reason 2 systems are used is because different cam grinders use different length flanks which could mean 2 very similar cam grinds could have totally different advertised durations but they would have very similar at 0.050" durations. Advertised duration numbers are impressive and great for selling cams and for desktop racers and example is a std hemi 6 has a advertised duration of nearly 260 degrees which sounds quite big, but its effective duration of only 195 degrees which is quite anemic. 
Why do they use the at 0.050" measurement well that is the point where the valve is open enough to allow some effective flow, below that for aerodynamic purposes the flow has effectively stopped.
Today we will talk a little about cam lift and duration.
In the previous item i explained what lift and duration are. Now to be confusing it must be always remembered that the duration of the cam lobe it is measured in crankshaft degrees not camshaft degrees. In a Otto cycle four-stroke engine the crankshaft rotates 2 full revolutions (720 degrees) for each power stroke. The camshaft travels at half crank speed so it only does 360 degrees per power stroke. 
As stated in terminology there is two types of duration advertised and at 0.050" and the latter is the effective duration.

Remember the 4 different engine strokes in the otto cycle. 
Intake, compression, power and exhaust or as some people know it suck, squeeze, bang and push.
Each stroke of the engine is 180-degrees so the intake or exhaust stroke are both 180 degrees. Already it can be seen that even the most basic cam has more effective duration in degrees on the intake lobe than the intake stroke has and the same for the exhaust lobe. A street or standard cam is configured to open the intake valve a little before the start of the intake stroke typically around a few degrees before TDC and it will usually only close the valve at some point after BDC into the start of the compression stroke. The exhaust valve timing will be very similar in that the exhaust valve will open before the power stroke is finished and the piston is still traveling down the cylinder and the exhaust valve will close after the intake stroke has started and intake valve is starting to open, sometime after TDC. Engine makers do this for a couple of reasons, firstly there is a 'dead zone' in piston travel around the end of each stroke, due to crank angles the piston can move almost no distance but the crank has moved thru about 20 degrees rotation. It gives more time for the exchange of gases, designers use this period to help get the gases moving while the piston is effectively stopped but the intake charge still has momentum and similarly the exhaust valve will open before the end of the power stroke when residual energy in the cylinder is doing little useful work. This energy can be used to help get the exhaust gases out more quickly, and by keeping the exhaust valve open a small amount when the intake valve is opening the incoming charges momentum can also scavenge (drive out) the remain exhaust gases. 

All cams have some overlap whereby the exhaust valve is still open while the intake valve is opening. The greater the overlap period the 'lumpier' the cam will be. The up side of overlap is the cylinders will be more effectively filled because there is more time for the intake charge to get in, but this better filling associated with the longer duration only occurs at higher rpms and the engine will have a greater HP potential. Also due to less low speed trapping efficiency the engine is a little more resistant to detonation which typically occurs at lower RPMs. 
The downside is lower trapping efficiency at lower speeds means less low speed torque and as some intake charge escapes in to the open exhaust port, therefore idle quality declines as well as fuel economy. A cam with a lot of duration and hence overlap usually requires a lowering of the cars gearing and a looser convertor to compensate for the significantly less low speed engine torque. As stated previously all cams have some overlap but most factory installed standard cams are so anemic that this overlap is so small and the valves are both opened to 0.050" or less during this period, so flow is effectively stopped and therefore of little impact on engine potential. Big capacity engines are less affected by intake charge dilution due to duration than smaller engines. Typically a wild long duration camshaft in a 2000cc engine would be relatively mild in a 6000cc motor. Many forum members may not know that Direct Connection once offered the 360 std cam as the first hot up step for 318 motors because it had more duration and lift. 
Tip: Often by installing a a cam on any given standard engine with a little more effective duration of say no more than 10 degrees and some more lift say around 0.040 to 0.060" will raise both high speed and low speed torque and HP without any major impact on idle quality and fuel economy. But don't be tempted to double that as adding 20 degrees of effective duration, as this would turn a drivable street motor into a lumpy monster requiring low gears but obviously (if other changes were also made) capable of significantly greater HP but at a higher rpm.

It is important to note that a particularly camshaft is only really going to be very efficient at a specific rpm point, at all other times it will be less than ideal, most factory cams are made to be a good compromise that is generally efficient at around 2000-2500-rpm the normal rev range of a street car engine. So it is easy to see while any small initial increase in duration and lift will deliver good results straight up relatively low in the rev range. Further changes from their will require higher engine revs to realise the potential. 
Now selecting a new cam can be daunting and it is easier to work from at 0.050" duration to compare different grinds, it is more important to get a cam duration to suit the engine you want to build, so focus on effective duration. Lift is also important but more so for mechanical reasons such as valve to piston clearance and valve train and lifter velocity. I find it is best to select a duration for the planned motor first then consider what the maximum lift that would work with your engine and find a cam in the catalogues that suits.

It is very important be realistic, a cam that looked good on paper might be a absolute chore and chew fuel in a daily driver making the car very unpleasant. What other mods are you doing to the engine/car so that the new cam will deliver the goods.
Think about what the car will be used for and what you are hoping to achieve, will your partner be driving that car and is she/he likely to tolerate a cantankerous engine that only sings at 4000 to 6000 revs and the rest of the time chugs because it has fallen off the cam. What gears you want to run and what fuel economy and wear and tear are you gunna accept.

What I do is, I do my research and settle on what cam would suit then I always pick the next 'more tame' cam on the grinders list. I have learned from bitter experience that cam descriptions are always optimistic (or maybe I just interpret them too optimistically) and as a result i have a number of cams around here from various motors I have played with that I took out after a short time because I did not like the way the engine drove, usually it had more cam and less drivability than I expected.

Fortunately chrysler did tuners a favour when they built their motors they did install a relatively large diameter lifter in both 6's and V8's which means that they can withstand much higher ramp speeds and spring loads that than engines from brand X and Y. So bigger cams generally don't have reliability issues for the valve train until you go wild.

Hemi 6 engines being a semi-hemi design have fairly deep chambers that allow a lot of cam lift before valve to piston clearance becomes a concern, not so good for the wedge motors in the V8's, where typically higher compression pistons and even quite small increase in valve lift requires valve pockets in the piston crown. 
Hemi 6 heads are fairly efficient for flow and therefore will easily take advantage of a new cams ability, wedge heads need a lot more work to flow well to suit big cams, but wedges are cross-flow and hemi's are not. Cross-flow design does aid filling and scavenging.
Original Hemi 6 cams are made of goats cheese they easily lose a lobe and lift and need to be always replaced when rebuilding a engine and as the market is small they are relatively expensive to buy. 
V8 cams are better quality and last better, but they are relatively cheap to buy because of the huge US market. 
Hemi 6 and V8 lifters will physically interchange but the hemi 6 has a bleed hole at the top to deliver oil via the pushrod to the valve rocker, the V8 does not.
Over the previous 2 posts we built the basics and now you have a selected lumpy stick for that special project and now we are going to dial it in, so that nice new grind works just as the cam designer/grinder intended.
Dialing in a cam is not overly difficult but you do need to be very methodical and careful not to make any mistakes.
Now you can just put the cam in and line up the dots on the timing gears and cross your fingers and hope for the best, but you won't know where the cam phasing is relative to the crankshaft and although on the balance of all probability it may be OK and the engine would be fine but it is likely it won't be optimised and it might be cost you HP. 
As members know every machine part has a manufacturing tolerance, and if those tolerances add up against you the cam could be a long way from optimum. I recently checked a std NOS factory hemi 6 cam and found the grind had been cut nearly 9 degrees retarded. 
We are tuners looking for all we can get from our rides so near enough should be not good enough or guess work is not gonna get the best results, right!
To dial a cam in you gunna need some special tools and some regular tools. The special tools required are a degree wheel and a dial indicator. Now you don't need one of those flash metal Snap-On wheel ( although that would be nice) I just use a cheapy plastic one I bought for a few dollars some years ago. Also you need a dial indicator (DTI) but every tuner worth his salt should have one of those and if he doesn't he should. I see them at swap meets for around 20 bucks so grab one next time you visit a swap or sunday flea market, also a magnetic base makes using the DTI easier but its not essential. 
First thing is to do is install the cam and timing gears initially just aligning the dots as a base line starting point. This is often referred to the cam being installed straight up.

Now fit your degree wheel to the nose of the crank using the V8's harmonic balancer bolt or with a hemi 6 you'll need to source a bolt that screws into the threads that are in the end of the crank, but because they are unused you may need to clean some dirt out of them first. 

The first step is to accurately find TDC on No 1 cylinder and set the degree wheel to match, so that you know any readings you take from the degree are accurate. 
There are a number of ways to do this, you cannot rely on the timing marks on the timing case because they are not accurate enough for this task (plus the timing case is still not installed yet). I have personally found the most accurate way of finding TDC was to install to temporarily block to the Cylinder to temporarily prevent the piston moving past TDC. If the head is off you simply construct a flat plate with a bolt approximately 15-20mm long welded or securely bolted to the centre of it, the plate should have some holes drilled in the plate so when it is placed over the cylinder with the piston lowered down the bore you can bolt it to the head surface using 2 bolts in 2 cylinder head bolt holes. When installed correctly the piston should be firmly blocked by the centre bolt some distance short ( the actual distance is irrelevant) of TDC when rotated clockwise by hand, once resting firmly against the blocking bolt now take a reading off the degree wheel, lets say for example it reads 57 degrees. I use a bit of bent sheet-metal held in position by a bolt on the front of the motor to act as a pointer for the degree wheel. Next rotate the engine anti-clockwise until the piston travels past BDC and again hits the blocking bolt, lets say this time you get 74 degrees, now add the two readings together and divide that figure by 2. 57 +74= 131-degrees so the new half figure is 65.5 degrees. 
Now loosen the degree wheel retainer nut and set it to 65.5 degrees ATDC and check tighten the degree wheel retaining bolt not allowing the wheel to move. If you have been accurate, when you rotate the crank CW all the way back again to the stop it should also read 65.5 BTDC, if it does then you are finished finding true TDC, If not you need to recheck by rotating the engine back and forward against the stop and readjust untill you read the same number on each side of the degree wheel. Remember the figures you get will be different and will depend on the length of your blocking bolt, my own homemade blocking tool stops the piston 36.5 crankshaft degrees either side of TDC when set correctly.
If the head is still on the engine you can still use the above methodology, but now instead of a blocking plate I use a blocking spark plug. You can make one of them by grabbing a used spark plug and knocking out the centre electrode and porcelain so that you have a hollow shell, then weld in a strong bit of rod that sufficiently pokes thru that once installed would block the piston rotation once the plug shell was installed in the number one cylinder. Then simply follow the remaining steps above to find true TDC. 
Now once you are happy you have now found true TDC make sure the degree wheel is tight and it cannot move position and after which you can now remove the blocking tool and set up your Dial test indicator (DTI) to dial in the cam.
In previous posts we have put the cam in the block, the timing gear was installed the degree wheel set up and we have accurately set TDC. Now we need to install a dummy lifter and a dial indicator, but we need to use a solid lifter so that any collapse in a hydraulic lifter does not introduce errors. I find that if you strip the guts out of a old hyd lifter and use the lifter shell only, that works fine, also grab a old pushrod not a chrysler one because both ends have a bullet shape and the DTI shaft will not locate. Grab a old BMC A series (mini etc) or something similar with a cup on the upper end as it helps to locate the dial test indicator shaft securely and gives very accurate readings. On Chrysler engines the second lifter bore is no1 inlet lobe not the 1st lifter bore as it is a exhaust lobe.

We are mainly interested with dialing in the cam intake lobe relative to the crankshaft and as the exhaust lobe is cut on the same shaft therefore its position is fixed relative to the intake lobe, so other than carrying out lift checks and confirming its duration is per the cam card we don't need to spend too much time on the exhaust.
With the dummy lifter & dummy pushrod installed in the second front lifter bore, set up the DTI on the pushrod, rotate the crank a few times to determine the lowest position on the cam lobe, this is called the base circle, zero the DTI on the base circle and now we begin to measure the duration.
Rotate the engine in the normal operating direction (CW from the front) and note the point when the DTI commences to lift, continue to rotate the crank slowly until it reads 0.050" lift above the base circle reading taken previously, read the degree wheel and compare this to your cam card, note this is the intake valve now opening and this reading is not the advertised duration but the at 0.050" (or effective) duration reading and make sure you compare it to the correct figures on the card.
It is advisable to repeat these cam dial in steps a number of times and take the degree wheel readings reading a few times to ensure that you are getting repeatable results. 
Continue to rotate the crankshaft until the DTI reaches the point where the maximum lift is reached and note the position on the degree wheel. This is the most important reading as far as accurately dialing the cam in. As this determines whether the cam is advanced or retarded or whether it is straight up when cut relative to the crankshaft.
The cam lobe has some dwell at its tip so the DTI will hover for a few crank degrees at the max lift point before it commences falling. To accurately determine the actual degree point of maximum lift, we need to take the mid point reading from the degree wheel do this by taking a reading when the DTI stops rising and when again it just starts falling and average the result.
Compare this to the cam card, typically most cams for petrol powered engines irrespective tune need to achieve maximum lift around 110 degrees crankshaft rotation after top dead centre (ATDC) this is the point where the piston is just past the halfway point on the intake stroke. Irrespective of what reading you find you will need to aim to achieve the same reading as your cam card says for best results. 
I have seen some cam makers recommend a max lift point as early at 106 degrees and some as late as 115 degrees so follow what the maker says. If you cam card says 108 degrees is the recommended max lift point and you read 112 on the degree wheel at max lift in your motor then the grind is said to be 4 degrees retarded and it will need to be advanced by 4 degrees with a adjustable timing gear set or offset dowel etc. The opposite needs to be done if for example your reading is 104 degrees and the card says 108 degrees for the recommended max lift point.
Get this right and the cam will work as the designer/ grinder intended. For the adventurous you can even advance the cam 1-3 degrees more than the card setting for slightly more bottom end torque at the expense of top end and retard it by a similar amount for a little more top end HP at the expense of bottom end. But it is not advisable to go much beyond the card settings as the results can be uncertain because you are also advancing and retarding the exhaust valve period at the same time which can produce mixed results.
Some cam manufacturers don't give a max lift reading on their card they give a specific lift reading at TDC to dial in their cam (Crow cams does this). I personally don't like lift at TDC because unless the cam is real wild you may not have more than 30 to 40 thou lift at TDC and in many cases the lifter could still be on the cam flanks between the base circle and the lobe proper whereby the degree wheel will move quite a bit with little change in lift evident on the DTI, so it is potentially not as repeatable system for novices. Most other cam makers give both a degree figures at max lift and and a lift figure at TDC. 

When satisfied with the degree reading at the cams max lift point and noting any corrections required.

Continue rotating the engine CW and read the degree wheel at the 0.050" lift point just prior to the intake valve lobe closing, note the reading and compare that to the cam cards figure for the closing point at 0.050" duration.
Follow the timing gear makers instructions to alter the cams position relative to the crankshaft by either advancing or retarding as required. 

When the corrections to the cams dial in point are complete, rotate the engine around again thru at least 2 full revolutions recheck the readings off the degree wheel to be certain that they are still right, once satisfied the task is now complete. 
Just a footnote for any readers that think that all this dial in work is too much effort and they will just line up the dots on their new cam, I can categorically state that I have built many engines and I have never yet found any cam installed that was correct at the straight up position (that is installed by the dots). They have always needed some correction usually only small amounts such as 2 degrees or so and therefore would not make that much different on a stocker engine but 2 degrees can make a world of difference on a performance engine.

Why is there variation? Remember machines that make cams, cranks and timing gears have tolerances, the parts themselves have production tolerances, key ways can be cut in the wrong position and there is wear & tear on the cam grinding machine then there is good old fashion human errors all that can mean the grind may not be in the right position on the cam billets relative to its own keyway and therefore will be incorrect relative to the crankshaft once installed. I once had a mini cam with the correct profile cut on the inlet lobe but the incorrect profile cut on the exhaust, I got my money back on that and went to another cam company.

I believe even if the engine is a stocker it is worth checking.