arve

Hello!
My spelling might suck cause i'm not from the U.S. I still hope you understand me.

I'm thinking of tuning my camaro iroc z-88 (350 tpi)

The chip is changed and so is the exhaust 3" . (not hedders yet)

I saw an article on this site about camshaft. (can i say cam's or must i use camshaft?) and how to choose. https://www.thirdgen.org/mods3

What i need to know is if what matters is the degrees seperation. And according to list my car is equipped with:

117 deg lobe sep from factory = 207/213. 415/.430. 443/.459 117deg 88-89 350,305
And i need one mayby 14, 12 or even 8. can i just use a stock cam from other car?

Like original 305cui aut 1987 cam? = 179/194.350/.384.373/.410109deg87 305 auto
or does the .05" Duration, 1.5:1 or 1.6:1 numbers (don' know what meen) in diagram matter?

Rolling Thunder

For starters welcome to the web site youll see there are many very knolegeable people here that are always more than willing to help. Also,I can understand your english prety well and my spelling sucks pretty bad too so no worries there. Well as youve probably seen cam's are a fairly complecated matter (yes you can just call it a cam its commonly understood cam refers to a camshaft). Now because i dont know what you already know about cams let me just throw a whole bunch of basic cam theory at you. Theres several specs to concern your self with primarily lift and duration but also things like degrees of lobe seperation. First the basic theory of cams is the more lift you have the more power you will make and the longer the duration the higher RPM your peek horsepower will occure at. Breaking that down even further the more lif you can get the more power you will make across the RPM range and long duration cams will make more high RPM horsepower but shorter dutation cams will make more low end torque. Not so bad so far right? Now this is really overly simplified but gives you a good idea of what it basically means. Now degrees of lobe seperation is kind of complex as its hard to really say its effects without taking into account the other specs. What it means is its the angle in degrees between the cams intake lobe peek and the cams exhaust lobes peek. What does this mean to you without getting real crazy into the science of its actual effect? A greater degree of lobe seperation will generally improve high end hp and give a wider power band where as a cam with less degrees of seperation will have increased low end torque and a narrow powerband. Other things you were asking about is the 1.5 or 1.6. This is the ratio of the rocker arms the 1.5 means 1 inch of lift on the cam will make the valve lift 1.5 inches with 1.5 ratio rocker arms or with 1.6 ratio rocker arms 1 inch of cam lift will be 1.6 inches of valve lift. Dosnt seem like much but it can make a bit of a difference in performance especially on cams with low lifts. Now the other number you were asking about the .050. There are 2 ways the duration specs are measured "advertised" and at ".050". "Advertised duration" can be measured from where ever the manufacture defines. However each manufacture could define the point they measure from differently. This means theres no way to really compare cams between different manufacturers. So many years ago an industry standard was set in place to measure the duration at .050 inches lift. That way all the duration measurements will be made from the same point on the cam and allows for the customer to be able to compare camshafts. Now your question about swapping cams from other motors you can do that but the cam your looking at from the 1987 305 will not perform as well as the duration is less and so is the valve lift. The current cam you have isnt too bad for a street car and concidering the amount of money and work it will take to change it ide say you would be better off changing to 1.6 ratio rockers (stock rocker arms are 1.5). This will improve valve lift giving you a little more power across the RPM range. Now if you did want to change the cam there are alot of nice aftermarket cams and a few talored specifically to TPI motors that will give a nice boost in performance more so than just adding 1.6 ratio rockers.

arve

Thanks that awsome answer!

I don't know what more to say... Thank you for taking the time, explaining it to me!

Rolling Thunder

Its no problem always glad to help. Its really only the basics of not only cam theory but also just one part of your motor. All parts must work together to achieve some goal otherwise if parts are not chosen carefully you could end up actually loseing performance. For example putting a very big long duration cam in a otherwise factory motor would be an example of where you would lose power as result of a mix matched build. Also concideration should be given as to what your trying to build a street car a race car whatever. Just gotta start out with a good plan as to what you want to do, reasurch your parts, and then start building.