How to pick a cam

-
Dusterdude96

Dusterdude96

Mopar Addict
Joined
Aug 24, 2010
Messages
33
Reaction score
0
Location
Hershey, PA
I've heard lots of times that choosing a cam is the hardest and most important choice you make when building an engine, but I've never heard how to pick the right cam for your engine based on the parts that are installed or the expected power output. How do you do this???
 
Ask an expert. If you dont know what to do, dont do it. Get help.

Do you have a combo your thinking about and need help picking a cam?
 
I called someone that knows Try Dave at Hughes Cams 309-745-9558
He answered all my questions and didnot try to sell me on anything
Roscoe
 
There are so many parameters to picking the right cam it'd take a long time to explain it. Your best bet if you don't know much about it is to call someone that knows. There are several good cam companies. A lot have a work sheet you fill out with all the specifications on your car with it's intended usage. They take all the answers in consideration when recommending a cam.
 
The guys above are actualy giving the best advice. Talk to a pro. Someone in the feild. But if you want to try yourself, the first thing your going to have to do is be honest about what you want, what you want the car to do and what can be done realistly.

First thing is to look at your part on the car and realize there has to be a balance. Follow the idea Edelbrock has put forth in the excellent marketing idea of "Power Packages" and note that everything is put toghter in a RPM powerband range. In example, the Performer is idle to 5500 and the RPM is a 2500 - 6500 rpm range and the Victor is higher and so on and so on....

Duration
When you look at a cams specs, the duration of the cam must fall into this range of parts intended to be used along with the gear ratio of the car. As well as your intended driving RPM range and what you plan to cruise at on the Hwy. The longer the duration, the higher the cruise RPM, the higher the gear ratio should be.

Also, split duration cams help the exhaust side of the engine breath. This exhaling is good for the inhaling for a fresher , fresh air and fuel charge with less comtamination. (SP!?) It helps increase power with the better air/fuel charge and extends the RPM range a few hundred RPM's.

Lift

High lift isn't really important to a daily driver or one with some teeth. If your looking to push the engine in the power department, use as much lift as the head can handle and yeild in lift when the port stalls in terms of it's air flow.

Centerline Normal HP cams are ground on a 110. This is a good centerline and it is most often ground in my the grinders. You need not worry about this really. Going higher produces a melloer idle and lower produces a ruffer idle. Theres more to this, but I'll stop here.

Also, when looking on line or in a catolog, stay in the section of street cams. If you start looking all over at different cams in different sections, even though your looking at a similar spec'd cam, there ground very differently and will react very differently in a engine.

Choose a oval track cam and you'll be very disapointed in a few areas like sreet abilty, idle, throttle response, narrow powerband, low torque.

Download Comp Cams "Cam Quest" for a few ideas. Follow the menu on the left and be honest about what you select and the choices given to you via the program are preety good with a few to select from.

Don't go crazy, according to anyone else you tell on what cam you selected, your wrong even if a pro helps. It's just one of those things.
 
Fishy, I agree and, this took a while to write out and only covers the basics. But IMO, it should get the wondering parties in the right ball park.

Even ater reading a good book and talking with tech from a few cam house's, theres alot left to be desired and learned. Cam opinion is like arguing what the best socks and underwear are to waer on any given day. While theres certainly a wrong set to use, the ones that will are allways up for hairsplitting opinions and remarks, etc....

I like changing them out for fun and just to see what'll it will do.
 
rumblefish360 said:
Fishy, I agree and, this took a while to write out and only covers the basics. But IMO, it should get the wondering parties in the right ball park.

Even ater reading a good book and talking with tech from a few cam house's, theres alot left to be desired and learned. Cam opinion is like arguing what the best socks and underwear are to waer on any given day. While theres certainly a wrong set to use, the ones that will are allways up for hairsplitting opinions and remarks, etc....

I like changing them out for fun and just to see what'll it will do.
Click to expand...

Great job on the write up Rumble. You covered a lot in a little time.
 
If i had to give a quick way to be on track then it would be the 5 parts of any combination outside the cam choice.

1)compression
2)converter stall speed
3)gear ratio
4)weight
5)head flow numbers

All 5 things are very important and the only rule is never go past the weakest link.
As you chose your cam you will hit one of the 5 listed as the weakest link.
For example:You have a 360 in a dart with a four barrel.
You have a stock 1800 stall speed converter.
You have 3.55 gears.
You have 9.1 to 1 compression.
You have stock heads with stock valves.

The weakest link is the converters stall speed.

PICK A CAM ON THE WEAKEST LINKS MAXIMUM ABILITY.

You will have to use a cam that give good performance at the converters 1800 rpms stall speed.

If you installed a 3000 converter then what would be your next weakest link???

Would it be the compression/heads/gears??????
>>>>..This is where you have to start making a choice on the nature of your car and it's intended use.

The next choice for maximum performance would be the gears and tire size.

A well thought out stock engine with headers and a four barrel with a 3000 converter and 355 gears can use a pretty healthy cam and when given the gear to run wide open will beat a more powerful engine that was not given the correct gearing.

Installing a set of 4.10 to 4.88 gears is best.
What determines the gear is the tire size you would like to run.

This goes back and forth but always is held back by the weakest link.

THIS GOES FOR EVERY PART YOU CHOOSE FOR YOUR COMBINATION.

Just ask your self then......WHATS MY WEAKEST LINK??????????

I hope this helps ya....:burnout:
 
One of the issues with cam selection for those who do it only occasionally, is the sheer number of different profiles available, and far too many, IMO, that are little more than duplicates of one-another. If you are looking through the various catalogue listings do not get confused when brand-x cam has 0.005" more lift or 2 degrees more, or less, duration. In a street car it simply won't make a difference. There are too many other factors involved.
If available, you might look through one of the old Direct Connection engine or race manuals. It is still viable information and may help provide some guidance.
 
You must log in or register to reply here.
-

Back
Top