Cam card specs meaning

I'm looking at cam cards trying to chose a cam, the intake exhaust opening/closing numbers are printed there and I was wondering what they tell you about the cam. The Lunati and the Hughes have similar numbers. The Comp Cam, although similar duration, the intake/exhaust opening and closing numbers are totally different.

Probably one of these will go into a 408 sb with Edelbrock heads, 10.3 ish compression, 3.23 gears.

These are the specs:

Lunati 60404, dur 234/242 @ 0.050, lift .513/.533, 110,
Intake: open 11 btdc/close 43 abdc, Exhaust: open 55 bbdc/ close 7 atdc
rpm 2200-6400, advertised dur 276/284

Hughes 3237, dur 232/237 @ 0.050, lift .540/.548, 110
Intake: open 9 btc/close 43 abc, Exhaust: open 51.5 bbc/close 5.5 atc
rpm 2300-5700

Comp CCA-CL20-227-4, dur 231/237 @0.050, .525/.525, 110
Intake: open 32 btdc/close 64 abdc, Exhaust: open 78 bbdc/close 30 atdc
rpm 2000-6,000, advertised dur 275/287

BTW, Edelbrock says their springs are good to .575 lift. Has anybody had any problems with the Edelbrock springs with cams in this general lift distance?

The numbers represent when they open and close in degrees/on the wheel.

Can't help you on the springs except you can compare the spring rates to see if there within a few pounds of the recomended spring from the cam manufacturers recomendations.

The differences you are seeing are the ramp speeds for the most part. The Hughes and Lunati use a very fast ramp, the Comps (even as an XE with the ".904" lifter profile lobes) are not as quick. So you see them starting to open later and close earlier. I am of the opinioin that there is a limimt to "too fast" for street cars, and i tend to stay away from rates of lift that are that fast because of idle time and oil issues. Of the three, the Hughes looks "the best". However, for a 4" stroke engine, you can go at least 10° more in duration at .050 with no loss of streetability. Something like the 20-225-4 (XE284H, not the 285HL) would be a nice match for stock port Edelbrocks.
As for the springs... lift is not what you use to determine what is the right spring. Pressures are. The Edelbrock singles are an ok general purpose spring. Unfortunately, any modern fast rate lobe bigger than around 225°@.050 needs more seat and open pressure than the stock springs can take. So figure on replacing them with matched ones for whatever cam you choose. A savvy machinist can usually find a part numebr for an inner spring that when used with Edelbrock's outer is perfect, for less money and you can re-use the Edelbrock retainers. Otherwise they will need to make sure th Edelbrock retainers work with the choice of dual spring. Also, any dual spring needs to be installed without the inner spring for the camshaft break in period. Otherwise you will very likely wipe off a few lobes. So when you do have the heads setup, remind them of that.

How could anyone ever choose a cam without knowing all the info about the car, put them all in a bucket with ice add a little lemon shake well and choose one.

You might want to call someone like Racer Brown 410-866-7660 after 2PM EST and get a cam number from him and see if any of those are close to what a REAL Mopar Cam Engineer suggests.

BTW: the Eddy spring number is only telling you the max lift to coil bind installed at the specified installed hieght...which is????

If it's any help, Edelbrock's Tech Department told me that the Hughes double spring #1111 can be installed on their small block heads with no modifications. Will work with the Eddy retainers.

I simply read the post and used what was given for examples. I also added what I've used in the past as example of something that might be good for use with those heads. The whole post sounds a little like just feeling things out. Not "pick me a cam". Touchy today Don?

'64 Cuda said:

If it's any help, Edelbrock's Tech Department told me that the Hughes double spring #1111 can be installed on their small block heads with no modifications. Will work with the Eddy retainers.

Click to expand...

yes...that is true

Thanks, very educational. I called Edelbrock, he said their springs have 120 pounds seat pressure. I gat a hold of Comp, he said the cam I have listed above needs 120 to 130 lbs seat pressure. Couldn't get a hold of Lunati tech.

Lunati wants dual springs and big pressures on everything in the "mopar lifter" lineup. We debated that a few weeks back. Seat pressure is only 1/2 the equasion. You need to know what they will be open too.

The reason the comp cams numbers are off is because they are based on advertised duration and the hughes and lunati are for duration at .050 lift.The numbers at .050 for the comp cam are intake opens 9.5 btdc/ closes 41.5 abdc exhaust opens 52.5bbdc/ closes 4.5 atdc based on a 106 installed center. Always go with the spring with the seat and over the nose pressures that are recomended by the cam company.

Update: I decided to go with the Hughes 232/237 @ .50, .540/.548 lift. After talking to the tech, he seemed to think it would be a good cam for my intended use of the car. I didn't have the Eddie heads yet, so I ordered them from Hughes. Same price as Summit, and he even waived the shipping fee for me. I also ordered a timing chain along with the cam, lifters, heads, and some gaskets.

We spoke about springs, and for an extra $100-$120, they would install the proper springs for the cam. Seemed like a reasonable price. They will be a single spring, so break in won't be an issue. Plus, I feel more comfortable talking to their reps than the others. BTW, he said the seat pressure needed for that cam is 135 lbs, and went on about some other specs, but my mind was in a fog.

I got a hold of Lunati's tech, he seemed pretty lethargic. I asked if the springs on the Eddie heads would be OK for the 60404 cam. I told him that the Eddie springs were rated at .575 lift, and he said that sounded fine. He really didn't bother to ask any more questions.

Thanks for all your input. I am learning a lot on this site.