how to pick the right cam?

hi i have a 1982 5.0 lts E-303 ford racing roller camshaft and the engine work great, a friend of mine want to change his stock roller camshaft (Mustang 1985 , carbureted roller cam), so how to pick the right camshaf whats depends? the carb.,intake, tranny?

any ideas?

When you thing of a cam, think of it as being the BOSS (had to) of your engine. It manages the other components in how much and when to flow air.

Your choice of carburetor, intake, heads, and exhaust all affect how you would want the cam to manage value events.

What kind of setup is/will he be running?
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the car have a 5.0 fully stock 1985 engine it no have any modif.
what dou you think about the choice in my mustang Spec:
holley street avenger 670 cfm, edelbrock performer intake, stock 5.0 h.o. heads, and a 2 1/4 exhaust whit a flow master mufflers, and a tail pipes. my actually cam (E-303 ford racing .498 lift and 220º dur.) is the best for my engine?

[img]/phpBB/images/smiles/icon_cool.gif[/img]first decide what rpm range the engine will spend 80-90% of its time in. for a street engine that is usually 1000-5000 rpm. then pick a cam that works in that rpm range. you can move the range up or down slightly, if you plan on doing some racing, or mostly freeway driving for instance you can change that rpm range to 1500-5500. once you have selected the cam, you want to make sure it will be compatible with the other parts you have. it is silly to use a cam designed for 3000-8000 rpm and make it work with stock heads, and a torker ll intake, and a 390 carb, and stock exhaust. match the components and you will have a powerfull, efficient engine.
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On a 306CID engine the stock E7 heads run out of gas at around 5200RPMS. If you're drag racing, you should pick your can to reach it's peak around here. Also your intake must match well.

The formula to determine the max HP 3.44 x (CFM@10" of water) = Max HP. The formula to determine the RPMs at which this will take place is (16000/CID) x CFM@10" of water = RPMS. The CFM above refers to the maximum that the head's intake will flow. In the case of the E7 head it's around 168CFM(maybe less!) at 28" of water.

BTW is the max HP for the above numbers predicts that this 306 will make about 347HP at 5200 if there is no loss from anywhere and everything is perfect. Remember, these are theoretical, maximum possible numbers. The real world numbers are usually considerable less.